Mangga

Wikipédia sakpunika sampun nggadhahi artikel ingkang cacahipun sauntawis kathah (kinten-kinten 13.074 artikel), nanging Wikipédia teras kémawon ngrembakaken cacahing artikel kasebat, sedaya dipun-serat para priyantun kados kita punika. Panjenengan saged udi mirsani miwiti artikel enggal utawi ngleresaken artikel-artikel ingkang sampun sumadya.

Kita nggadhahi kathah kebijakan lan pitedah ingkang langkung saé menawi dipun-pirsani rumiyin, kadosta sudut pandang netral (NPOV) ingkang tegesipun artikel-artikel ingkang dipun serat kedah nétral lan mboten ngandhut prasangka, lan kedah saged mewakili pirang sudut pandhang sing béda nanging tetep obyektif lan sopan. Kabèh sumbangan kanggo Wikipédia mau diterbitaké miturut Lisensi Dokumentasi Bebas GNU (GFDL). Lisensi GDFL dienggo kanggo mesthèkake yèn Wikipédia lan artikel-artikelé tetep bisa bebas digunakaké dening sapa waé (Delok hak cipta karebèn mangerti informasi luwih lanjut).


Mangga dipun-cobi!

Cara

[sunting] Ngrêröncé (mengedit/menyunting)
Sinten kemawon kenging ngewahi utawi nggantos sedaya kaca ing Wikipédia (kelebet kaca punika!). Nge-klik sunting ing perangan nginggil kaca punika menawi panjenengan rumaos perlu dipun-leresaken. Panjenengan mboten kedah nggadhahi keprigelan (keahlian) khusus; Panjenengan ugi mboten kedah login supados saged ngewahi kaca (nanging langkung prayogi menawi login rumiyin).

Cara ingkang paling gampil kanggé miwiti nggih milai kemawon ngginakaken Wikipédia kados menawi panjenengan ngginakaken ensiklopédia sanesipun, nanging menawi penjenengan nemahi masalah—salah serat utawi artikel ingkang mboten patos cetha—klik kemawon "sunting" lajeng leresaken bab kasebat.

Wikipédia: Panjenengan kedah wantun ngreroncé kaca. Menawi panjenengan rumaos perlu ngleresaken isi kaca, mangga dipun laksanakaken! Sampun ngantos ajrih menawi lepat (lha wong mèh kabèh sing nyumbang artikel Wikipédia ya naté gawé salah nalika wiwitan mèlu partisipasi nèng Wikipédia). Saumpaminipun panjenengan sampun kebacut damel klintu, taksih saged dipun-leresaken bènten wekdal, dening panjenengan piyambak utawi réncang sanèsipun. Mbok menawi panjenengan ngraos bab punika radi agor-agori! Mangga dipun-pirsani kémawon jawaban atas kritikan terhadap Wikipédia supados saged mudheng kados pundi larah-larahipun cara ingkang kados mekaten pranyata saged mrantasi damel.

artikel

[sunting] Gegambaran Wikipedia
Kaca Wikipédia nyaosaken kathah artikel ngenani punapa kémawon. Supados saged mirsani artikel kasebat, mlebet kemawôn dumateng Kaca Utama, lajeng padôsi babagan utawi artikel ingkang kabetahaken, lajeng milai kemawon anggenipun njelajah. Ugi, wônten köthak kanggé madosi perkawis ingkang wonten sesambunganipun ing perangan pinggir saben kaca.

Menawi panjenengan manggihi perkawis ingkang mérak manah tur ngremenaken, mangga kersaha nilaraken seratan wonten kaca dhiskusi. Caranipun, sepisan klik pranala diskusi (wonten ing perangan nginggil kaca) kangge mlebet kaca diskusi, lajeng klik + ing kaca diskusi (wonten ing perangan nginggil kaca, sebelah tengen pranala sunting). Kita bingah menawi pikantuk tanggapan ingkang positif.

Jawa

Wikipedia:Sugeng rawuh
Saka Wikipédia, Ènsiklopédhi Bébas ing basaWikipedia:Sugeng rawuh
Saka Wikipédia, Ènsiklopédhi Bébas ing basa Jawa / Saking Wikipédia, Bauwarna Mardika mawi basa Jawi
Langsung menyang: pandhu arah, golèk
Wikipedia punika bauwarna bébas ingkang dipun sêrat kanthi gotong-royong déning para rawuh sami ingkang sampun kersa peparing kawigatosan. Situs punika kasebatWikiWiki, ingkang tegesipun: sinten kémawon, panjenengan ugi, saged ngewahi saha nyunting saben artikel ingkang cumaôs. Caranipun gampil saestu, namung nge-klik pranala sunting (ngröncé) ingkang wonten ing perangan nginggil saben artikel Wikipédia. / Saking Wikipédia, Bauwarna Mardika mawi basa Jawi
Langsung menyang: pandhu arah, golèk
Wikipedia punika bauwarna bébas ingkang dipun sêrat kanthi gotong-royong déning para rawuh sami ingkang sampun kersa peparing kawigatosan. Situs punika kasebatWikiWiki, ingkang tegesipun: sinten kémawon, panjenengan ugi, saged ngewahi saha nyunting saben artikel ingkang cumaôs. Caranipun gampil saestu, namung nge-klik pranala sunting (ngröncé) ingkang wonten ing perangan nginggil saben artikel Wikipédia.

Free

Sister projects
Wikipedia is hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other projects:

Commons
Free media repository Wikinews
Free-content news Wiktionary
Dictionary and thesaurus
Wikiquote
Collection of quotations Wikibooks
Free textbooks and manuals Wikisource
Free-content library
Wikispecies
Directory of species Wikiversity
Free learning materials and activities Meta-Wiki
Wikimedia project coordination

Please note that while other sites may also use MediaWiki software and therefore look similar to Wikipedia, or may have a name that includes 'Wiki-' or '-pedia', or a similar domain name, the only projects which are part of the Wikimedia Foundation are those listed above, even if they claim to be part of it.

See also
Wikipedia
Ten things you probably didn't know about Wikipedia
meta:Power structure

References
^ "Quarterly update to OED online: New edition: Prakrit to prim", Oxford English Dictionary, 15 March 2007
^ Wikipedia announcements — May 2001.
^ Wikipedia announcements — September 2001.
^ Wikimedia Foundation press release. Wikimedia Foundation (2006-06-12).
^ Jimmy Wales. Charlie Rose (46:22) (internet video) [TV-Series]. Google Video: Charlie Rose. Retrieved on 2006-12-08.
^ Current staff from the Wikimedia Foundation. The Wikimedia Foundation. Retrieved on 2006-12-08.
^ Current staff from the Wikimedia Foundation. The Wikimedia Foundation. Retrieved on 2007-04-23.
^ Mailing list post by the Chair of the Wikimedia Foundation's Board of Trustees announcing the appointment.
^ http://wikimediafoundation.org/w/index.php?title=Current_staff&diff=21563&oldid=21560
^ Current staff from the Wikimedia Foundation. The Wikimedia Foundation. Retrieved on 2007-07-11.
^ Metz, Cade. "Wikipedia COO was convicted felon", 2007-12-13. Retrieved on 2007-12-27.
^ Bergstein, Brian. "Felon Became COO of Wikipedia Foundation", 2007-12-21. Retrieved on 2008-03-26.
^ January 2008 Wikimedia Organization employee chart - January 2008 Wikimedia Organization employee decriptions
^ Gardner, Sue (2008-01-30). [Foundation-l] [Announcement] New CFOO: Veronique Kessler. Retrieved on 2008-01-30.
^ history flow: results. IBM.
^ Bill Thompson, "What is it with Wikipedia?", BBC, 16 December 2005.
^ The founder of Wikipedia is the sole individual empowered to override this process, but has stated in public that extreme circumstances aside, he will not do so.

Further reading

articles: Deutsch

Research help and similar questions
Facilities for help for users researching specific topics can be found at:

Wikipedia:Requested articles — to suggest or request articles for the future.
Wikipedia:Reference desk — to ask for help with any questions, or

Also, you could try the Wikimedia Foundation meta-wiki, a site for coordinating the various Wikipedia projects and sister projects (and abstract discussions of policy and direction), and there are many different places for submitting bug reports and feature requests.

For a full list of contact options, see Wikipedia:Contact us.


Related versions and projects
This Wikipedia is written in English. Started in 2001, it currently contains 2,412,241 articles. Many other Wikipedias are available; the largest are listed below.

More than 300,000 articles: Deutsch · Español · Français · Italiano · Nederlands · ??? · Polski · Português
More than 100,000 articles: Català · Norsk (bokmål) · Româna · ??????? · Suomi · Svenska · Türkçe · ?????????? · Volapük · ??
More than 50,000 articles: ??????? · Bahasa Indonesia · ????????? · Ceština · Dansk · Eesti · Esperanto · ????? · ??? · Lietuviu · Magyar · Slovencina · Slovenšcina · ??????
More than 20,000 articles: Bahasa Melayu · ???? ???/????????????? ??????? · Bosanski · · ???????? · English (simple) · Euskara · ????? · Galego · Hrvatski · Íslenska · ??????? · Latina · Lëtzebuergesch · Norsk (nynorsk) · Shqip · ??? · Ti?ng Vi?t
Complete list · Multilingual coordination

on.

Research help and similar questions
Facilities for help for users researching specific topics can be found at:

Wikipedia:Requested articles — to suggest or request articles for the future.
Wikipedia:Reference desk — to ask for help with any questions, or in finding specific facts.
Because of the nature of Wikipedia, it's encouraged that people looking for information should try and find it themselves in the first instance. If however you come across valid information missing from Wikipedia, be bold and add it yourself so others can gain from your research too!


Community discussion
For specific discussion not related to article content or editor conduct, see the Village pump, which covers such subjects as announcements, policy and technical discussion, and information on other specialized portals such as the help, reference and peer review desks. The Community Portal is a centralized place to find things to do, collaborations, and general editing help information, and find out what's going on.


Contacting individual Wikipedia editors
If you need more information, the first place to go is the Help:Contents. To contact individual contributors, leave a message on their talk page. Standard places to ask policy and project-related questions are the village pump, online, and the Wikipedia mailing lists, over e-mail. You can also reach other Wikipedians via IRC and e-mail.

This

Talk pages — the associated discussion page for discussion of an article or policy's contents. This is usually the first place to go.
Wikipedia:Vandalism — to report vandalism (you're encouraged to fix vandalism yourself as well as report it)
Dispute resolution — for disputes which remain unresolved within an article's talk space.
Village pump — the Wikipedia discussion area, part of the community portal.
See also:

Bug tracker, for reporting issues with the Wikipedia web site or the MediaWiki software that runs it
Village pump: proposals page for non-policy suggestions
Wikipedia:Help desk — Wikipedia's general help desk, if other pages haven't answered your query.

FAQ

Feedback and questions
Wikipedia itself is run as a communal effort. It is a community project whose end result is an encyclopedia. Feedback about content should, in the first instance, be raised on the discussion pages of those articles. You are invited to be bold and edit the pages yourself to add information or correct mistakes if you are knowledgeable and able to do so.


Frequently asked questions (FAQ)
Main article: Wikipedia:FAQ
FAQ index: Index of all Wikipedia FAQ pages

Giving feedback
There is an established escalation and dispute process within Wikipedia, as well as pages designed for raising questions, feedback, suggestions and comments:

their own

Editorial quality review
As well as systems to catch and control substandard and vandalistic edits, Wikipedia also has a full style and content manual, and a variety of positive systems for continual article review and improvement. Examples of the processes involved include peer review, good article assessment, and featured articles, a rigorous review of articles which are desired to meet the highest standards and showcase Wikipedia's capability to produce high quality work.

In addition, specific types of article or fields often have their own specialized and comprehensive projects, assessment processes (such as biographical article assessment), and expert reviewers within specific subjects. Nominated articles are also frequently the subject of specific focus under projects such as the Neutrality Project or covered under editorial drives by groups such as the Cleanup Taskforce.


Technical attributes
Wikipedia uses MediaWiki software, the open-source program used not only on Wikimedia projects but also on many other third-party websites. The hardware supporting the Wikimedia projects is based on almost 100 servers in various hosting centers around the world. Full descriptions of these servers are available on this meta page. For technical information about Wikipedia, you can check Technical FAQs.

reported

Intentional vandalism can be reported and corrected by anyone.
Unresolved disputes between editors, whether based upon behavior, editorial approach or validity of content, can be addressed through the talk page of an article, through requesting comments from other editors or through Wikipedia's comprehensive dispute resolution process.
Abuse of user accounts, such as the creation of Internet sock puppets or solicitation of friends and other parties to enforce a non-neutral viewpoint or inappropriate consensus within a discussion, or to disrupt other Wikipedia processes in an annoying manner, are addressed through the sock puppet policy.
In addition, brand new users (until they have established themselves a bit) may at the start find that their votes are given less weight by editors in some informal polls, in order to prevent abuse of single purpose accounts.

projects within

Editorial administration, oversight and management
Main article: Wikipedia:Editorial oversight and control
The Wikipedia community is largely self-organising, so that anyone may build a reputation as a competent editor and become involved in any role they may choose, subject to peer approval. Individuals often will choose to become involved in specialised tasks, such as reviewing articles at others' request, watching current edits for vandalism, watching newly created articles for quality control purposes, or similar roles. Editors who find that editorial administrator responsibility would benefit their ability to help the community may ask their peers in the community for agreement to undertake such roles; a structure which enforces meritocracy and communal standards of editorship and conduct. At present around a 75–80% approval rating after enquiry, is considered the requirement for such a role, a standard which tends to ensure a high level of experience, trust and familiarity across a broad front of projects within Wikipedia.

A variety of software assisted systems and automated programs help several hundred editors to watch for problematic edits and editors. An arbitration committee sits at the top of all editorial and editor conduct disputes,[17] and its members are elected in three regularly rotated tranches by an established enquiry and decision making process in which all regular editors can equally participate.


Handling disputes and abuse
Main articles: Wikipedia:Vandalism, Wikipedia:Dispute resolution, Wikipedia:Consensus, Wikipedia:Sock puppet, Wikipedia:Conflict of interest
Wikipedia has a rich set of methods to handle most abuses that commonly arise; these methods are well tested and should be relied upon.

Wikipedia is not

Wikipedia has robust version and reversion controls. This means that poor quality edits or vandalism can quickly and easily be reversed or brought up to an appropriate standard by any other editors, so inexperienced editors cannot accidentally do permanent harm if they make a mistake in their editing. As there are many more editors intent upon good quality articles than any other kind, articles that are poorly edited are usually corrected promptly.


Wikipedia content criteria
Main article: Wikipedia:Wikipedia in brief
Wikipedia content is intended to be factual, notable, verifiable with external sources, and neutrally presented, with external sources cited.

The appropriate policies and guidelines for these are found at:

Wikipedia:What Wikipedia is not summarizes what Wikipedia is, and what it is not.
Wikipedia:Neutral point of view Wikipedia's core approach, neutral unbiased article writing.
Wikipedia:No original research what is, and is not, valid information.
Wikipedia:Verifiability what counts as a verifiable source and how a source can be verified.
Wikipedia:Citing sources sources should be cited, and the manner of doing so.
Wikipedia:Manual of Style articles should follow this style guide
These can be abbreviated to WP:NOT, WP:NPOV, WP:NOR, WP:V, WP:CITE, WP:MOS respectively.

uses a

Editing Wikipedia pages
Main article, including list of common mark-up shortcuts: Wikipedia:How to edit a page
Wikipedia uses a simple yet powerful page layout to allow editors to concentrate on adding material rather than page design. These include automatic sections and subsections, automatic references and cross-references, image and table inclusion, indented and listed text, links ISBNs and math, as well as usual formatting elements and most world alphabets and common symbols. Most of these have simple formats that are deliberately very easy and intuitive.

page

Contributing to Wikipedia
Main articles: Contributing to Wikipedia, First steps in editing articles, New contributors' help page
Guide to fixing vandalism: Help:Reverting
Anyone can contribute to Wikipedia by clicking on the Edit this page tab in an article. Before beginning to contribute however, you should check out some handy helping tools such as the tutorial and the policies and guidelines, as well as our welcome page. It is important to realize that in contributing to Wikipedia, users are expected to be civil and neutral, respecting all points of view, and only add verifiable and factual information rather than personal views and opinions. "The five pillars of Wikipedia" cover this approach and are recommended reading before editing. (Vandals are reported via the Administrator Notice Board and may be temporarily blocked from editing Wikipedia.)

Most articles start as stubs, but after many contributions, they can become featured articles. Once you have determined that there is no article on Wikipedia on a topic you are interested in, you may want to request that the article be written (or you could even research the issue and write it yourself). Wikipedia has many on-going projects, focused on specific topic areas or tasks, which help coordinate editing. The hope of any contributor is to provide useful and accurate information to others, and the projects help coordinate efforts.

Risk

See also: Reliability of Wikipedia and Wikipedia:Researching with Wikipedia

Disclaimers
Disclaimers
Core disclaimers
General
Legal
Medical
Content
Risk

Other
Academic use
Non-Wikipedia

Main article: Wikipedia:Disclaimers
Wikipedia disclaimers apply to all pages on Wikipedia.

Wikipedia, in common with many websites, makes its disclaimers highly visible, a practice which at times has led to commentators citing these in order to support a view that Wikipedia is unreliable. A selection of similar disclaimers from places which are often regarded as reliable (including sources such as Encyclopædia Britannica, Associated Press, and the Oxford English Dictionary) can be read and compared at Non-Wikipedia disclaimers. Wikipedia content advisories can also be found here.

fake

Studies suggest that Wikipedia is broadly as reliable as Encyclopedia Britannica, with similar error rates on established articles for both major and minor omissions and errors.[15] There is a tentative consensus, backed by a gradual increase in academic citation as a source, that it provides a good starting point for research, and that articles in general have proven to be reasonably sound. That said, articles and subject areas sometimes suffer from significant omissions, and while misinformation and vandalism are usually corrected quickly, this does not always happen. (See for example this incident in which a person inserted a fake biography linking a prominent journalist to the Kennedy assassinations and Soviet Russia as a joke on a co-worker which went undetected for 4 months, saying afterwards he "didn’t know Wikipedia was used as a serious reference tool.") Therefore, a common conclusion is that it is a valuable resource and provides a good reference point on its subjects.

how

The MediaWiki software which runs Wikipedia retains a history of all edits and changes, thus information added to Wikipedia never "vanishes", and is never "lost" or deleted. Discussion pages are an important resource on contentious topics. There, serious researchers can often find a wide range of vigorously or thoughtfully advocated viewpoints not present in the consensus article. Like any source, information should be checked. A 2005 editorial by a BBC technology writer comments that these debates are probably symptomatic of new cultural learnings which are happening across all sources of information (including search engines and the media), namely "a better sense of how to evaluate information sources."[16]

increases

Wikipedia is open to a large contributor base, drawing a large number of editors from diverse backgrounds. This allows Wikipedia to significantly reduce regional and cultural bias found in many other publications, and makes it very difficult for any group to censor and impose bias. A large, diverse editor base also provides access and breadth on subject matter that is otherwise inaccessible or little documented. A large number of editors contributing at any moment also means that Wikipedia can produce excellent encyclopedic articles and resources covering newsworthy events within hours or days of their occurrence. It also means that like any publication, Wikipedia may reflect the cultural, age, socio-economic, and other biases of its contributors. There is no systematic process to make sure that "obviously important" topics are written about, so Wikipedia may contain unexpected oversights and omissions. While most articles may be altered by anyone, in practice editing will be performed by a certain demographic (younger rather than older, male rather than female, rich enough to afford a computer rather than poor, etc) and may, therefore, show some bias. Some topics may not be covered well, whilst others may be covered in great depth.
Allowing anyone to edit Wikipedia means that it is more easily vandalized or susceptible to unchecked information, which requires removal. While blatant vandalism is usually easily spotted and rapidly corrected, Wikipedia is more subject to subtle viewpoint promotion than a typical reference work. However, bias which would be unchallenged in a traditional reference work is likely to be ultimately challenged or considered on Wikipedia. While Wikipedia articles generally attain a good standard after editing, it is important to note that fledgling, or less well monitored, articles may be susceptible to vandalism and insertion of false information. Wikipedia's radical openness also means that any given article may be, at any given moment, in a bad state, such as in the middle of a large edit, or a controversial rewrite. Many contributors do not yet comply fully with key policies, or may add information without citable sources. Wikipedia's open approach tremendously increases the chances that any particular factual error or misleading statement will be relatively promptly corrected. Numerous editors at any given time are monitoring recent changes and edits to articles on their watchlist.
Wikipedia is written by open and transparent consensus — an approach that has its pros and cons. Censorship or imposing "official" points of view is extremely difficult to achieve and almost always fails after a time. Eventually for most articles, all notable views become fairly described and a neutral point of view reached. In reality, the process of reaching consensus may be long and drawn-out, with articles more fluid or changeable for a long time compared while they find their "neutral approach" that all sides can agree on. Reaching neutrality is occasionally made harder by extreme-viewpoint contributors. Wikipedia operates a full editorial dispute resolution process, that allows time for discussion and resolution in depth, but also permits months-long disagreements before poor quality or biased edits will be removed.

to editorial

Strengths, weaknesses, and article quality in Wikipedia
Main articles: Wikipedia:Why Wikipedia is so great and Wikipedia:Why Wikipedia is not so great
Wikipedia's greatest strengths, weaknesses, and differences all arise because it is open to anyone, has a large contributor base, and articles are written by consensus according to editorial guidelines and policies.

vs

Wikipedia vs. paper encyclopedias
Main article: Wiki is not paper (on Wikimedia Meta-Wiki)
Wikipedia has advantages over traditional paper encyclopedias. Wikipedia has a very low "publishing" cost for adding or expanding entries and a low environmental impact, since it need never be printed. Also, Wikipedia has wikilinks instead of in-line explanations and it incorporates overview summaries (article introductions) with the extensive detail of a full article. Additionally, the editorial cycle is short. A paper encyclopedia stays the same until the next edition, whereas writers update Wikipedia at every instant, around the clock, ensuring that it stays abreast of the most recent events and scholarship.

of

While the overall trend is generally upward, it is important to use Wikipedia carefully if it is intended to be used as a research source, since individual articles will, by their nature, vary in standard and maturity. There are guidelines and information pages designed to help users and researchers do this effectively, and an article that summarizes third-party studies and assessments of the reliability of Wikipedia.

ideal

The ideal Wikipedia article is balanced, neutral and encyclopedic, containing comprehensive notable, verifiable knowledge. An increasing number of articles reach this standard over time, and many already have. Our best articles are called Featured Articles (and display a small star in the upper right corner of the article), and our second best tier of articles are designated Good Articles. However, this is a process and can take months or years to be achieved, as each user adds their contribution in turn. Some articles contain statements and claims which have not yet been fully cited. Others will later have entire new sections added. Some information will be considered by later contributors to be insufficiently founded, and may be removed or expounded.

be

Users should be aware that not all articles are of encyclopedic quality from the start, and may contain false or debatable information. Indeed, many articles start their lives as partisan, and after a long process of discussion, debate and argument, they gradually take on a neutral point of view reached through consensus. Others may for a while become caught up in a heavily unbalanced viewpoint which can take some time — months perhaps — to achieve better balanced coverage of their subject. In part, this is because editors often contribute content in which they have a particular interest and do not attempt to make each article that they edit comprehensive. However, eventually additional editors expand and contribute to articles and strive to achieve balance and comprehensive coverage. In addition, Wikipedia operates a number of internal resolution processes that can assist when editors disagree on content and approach, and eventually the editors generally reach a consensus on ways to improve the article.

over a

Using Wikipedia as a research tool
Main articles: Wikipedia:Researching with Wikipedia and Wikipedia:Citing Wikipedia
As a wiki, articles are never complete. They are continually edited and improved over time, and in general this results in an upward trend of quality, and a growing consensus over a fair and balanced representation of information.

navigation

Basic navigation in Wikipedia
Main article: Wikipedia:Basic navigation
Wikipedia articles are all linked, or cross-referenced. Wherever you see highlighted text like this, it means there is a link to some relevant article or Wikipedia page with further in-depth information elsewhere if you need it. Holding your mouse over the link will often show you where a link will take you. You are always one click away from more information on any point that has a link attached. There are other links towards the ends of most articles, for other articles of interest, relevant external web sites and pages, reference material, and organized categories of knowledge which you can search and traverse in a loose hierarchy for more information. Some articles may also have links to dictionary definitions, audio-book readings, quotations, the same article in other languages, and further information available on our sister projects. You can add further links if a relevant link is missing, and this is one way to contribute.

might enjoy

You also might enjoy reading Wikipedia in other languages. Wikipedia has more than two hundred different languages (see other language versions), including a Simple English version, and related projects include a dictionary, quotations, books, manuals, and scientific reference sources, and a news service (see sister projects). All of these are maintained, updated, and managed by separate communities, and often include thought-provoking information and articles which can be hard to find through other common sources.

Wikipedia

Rob Halsell: Information Technology Manager and Server Administrator.
Barbara, Sandy and Vishal are expected to finish with the foundation at the end of January 2008. Oleta is expected to stay until the end of March. Following the closure of the St. Petersburg office, Rob will continue to work for the foundation out of Tampa, maintaining the Tampa servers.[13]

February 2008:

Veronique Kessler was hired as Chief Financial and Operating Officer (CFOO) with a start date of February 4, 2008.[14]


Making the best use of Wikipedia

Exploring Wikipedia
Main article: Wikipedia:Explore
Many visitors come to this site to acquire knowledge, others to share knowledge. In fact, at this very instant, dozens of articles are being improved, and new articles are also being created. You can view changes as they happen at the Recent changes page. You also can view random articles. Over 2,000 articles have been designated by the Wikipedia community as featured articles, exemplifying the best articles in Wikipedia. Another 4,000 articles are designated as good articles. Wikipedia also has portals, which organize content around topic areas. You may also search for articles using the search box on the left side of the screen.

Executive

In December 2007, it was revealed by The Register[11] that former COO Carolyn Doran was a convicted felon, with a DUI arrest during her tenure at the Foundation and a substantial criminal history, including shooting her boyfriend and charges of complicity in credit card forgery.[12]


2008
January 2008:

San Francisco, California, United States:
Cheryl Owens (formerly Steffen): New, Sue Gardner's assistant; started December 10, 2007.
Erica Ortega: New, Office Manager; started December 10, 2007.
Brion Vibber: foundation's first employee; Chief Technical Officer (CTO);
Cary Bass: Volunteer Coordinator;
Kul Takanao Wadhwa:Head of Business Development, started January 3, 2008;
Erik Möller: New to the staff but formerly Member of the Board of Trustees; Deputy Director; started December 31, 2007
Mike Godwin: Legal Counsel, started in July 2007; in the San Francisco office January 30, 2007.
Sue Gardner: Executive Director (ED), started in June 2007.
Outside the United States:
Tim Starling: Software Developer, Australia;
Delphine Ménard : Chapters Coordinator, Frankfurt;
Mark Bergsma: System Administrator, Eindhoven, the Netherlands;
Jay Walsh: New, Head of Communications, Vancouver Island, Canada; started January 10, 2007.
St Petersburg, Florida, United States:
Barbara Brown: Office Manager;
Sandy Ordonez: Communications;
Vishal Patel: Business Development;
Oleta McHenry: Accountant;

Vishal

Danny Wool, officially the grant coordinator but also largely involved in fundraising and business development, resigned in March 2007. In April 2007, the foundation added a new position, Chapter Coordinator, and appointed Delphine Ménard, then in the position of Volunteer Coordinator, to fill it. Cary Bass was appointed to replace Ménard.

In May 2007, Vishal Patel was hired to assist in business development.[7]

In July 2007, Mike Godwin was hired as general counsel and legal coordinator.[8] That same month, Carolyn Doran left as COO[9] and Sue Gardner was hired as consultant and special advisor. The number of full-time staff members, after these hires, was still fewer than ten.[10]

technical

As of December 8, 2006, the Wikimedia Foundation's list of current staff named three other technical independent contractors (part-time hardware manager Kyle Anderson in Tampa, full-time MediaWiki software developer Tim Starling, and part-time networking coordinator Mark Bergsma).

Brad Patrick ceased his activity as interim director in January 2007 and then resigned from his position as legal counsel in April 2007.

In January 2007, Carolyn Doran was named Chief Operating Officer and Sandy Ordonez came on board as Communication Manager.[6] Doran had begun working as a part-time bookkeeper for the foundation in 2006 after being sent by a temporary agency.

few

Employees
January 2008 Wikimedia Organization employee chart
January 2008 Wikimedia Organization employee descriptions
The functions of the Wikimedia Foundation were, for the first few years, executed almost entirely by volunteers. In the spring of 2005, the foundation only had two employees, Danny Wool and Brion Vibber. Though the number of employees has grown, the bulk of foundation work continues to be done by volunteers, with the foundation having very few employees.

On June 16, 2006, Brad Patrick, previously a practicing attorney who had done some pro bono work with the foundation starting in fall 2005, was named general counsel and interim executive director; in the latter capacity, Patrick was designated to assist the board in its search for a permanent executive director.[4]

As of October 4, 2006, the Wikimedia Foundation had five paid employees: two programmers (software manager Brion Vibber in California and server administrator Chad Perrin in Tampa); "to answer the phones", administrative assistant Barbara Brown; to handle fundraising and grants, Danny Wool; and to manage, interim executive director Brad Patrick.[5]

project

At a project level the foundation also co-ordinates the global policies, practices and facilities of Wikipedia in all languages and its sister projects, provides legal and intellectual property input as required, and is formally responsible for the development of the open source Wikipedia software (Mediawiki) as requirements change.

In line with its goal of producing reference material free to all people, the foundation also operates a Metawiki where matters impinging upon all projects, global discussions can take place, and global policies can be formally documented and developed, and an incubator for proposed new projects and new languages, to facilitate their launch and early stage development. As of August 2007 there are around 100 new reference projects in various stages of development initiated by members of the Wikipedia and related communities.

Foundation

Although the Wikimedia Foundation owns the site, it is largely uninvolved in writing and daily operations.


The Wikimedia Foundation
Main articles: Wikimedia Foundation and m:Main Page
The Wikimedia Foundation, Inc. is a non-profit charitable organization founded in St. Petersburg, Florida, United States in 2002 and headquartered in San Francisco, California. The foundation acts as the legal umbrella body for Wikipedia and all related sister projects, and is the owner of all trademarks and intellectual property rights related to Wikipedia. Almost all of its functions are undertaken by volunteers within the Wikipedia community, supplemented by a very small paid staff, an Advisory Board of around 15 expert individuals, and a Board of Trustees. Branches of the foundation exist and are being added to in an ongoing manner, in a number of countries, focussing upon reference information, publication, funding, and other projects specific to the location.

rectify

Several mechanisms are in place to help Wikipedia members carry out the important work of crafting a high-quality resource while maintaining civility. Editors are able to watch pages and techies can write editing programs to keep track of or rectify bad edits. Over 1,500 administrators with special powers ensure that behaviour conforms to Wikipedia guidelines and policies. Where there are disagreements on how to present facts editors work together to arrive at an article which fairly represents current expert opinion on the subject. Editors who fail to work with others in a civil manner can be temporarily or permanently banned from editing Wikipedia by the administrators.

Who

Wikipedia contributors
Main articles: Wikipedia:Who writes Wikipedia and Wikipedia:Wikipedians
Anyone with internet access can edit Wikipedia, and this openness encourages inclusion of a tremendous amount of content. About 75,000 editors — from expert scholars to casual readers — regularly edit Wikipedia, and these experienced editors often help to create a consistent style throughout the encyclopaedia, following our Manual of Style.

copyrights

Trademarks and copyrights
Wikipedia is a registered trademark of the nonprofit Wikimedia Foundation, which has created an entire family of free-content projects. On all of these projects, you are welcome to be bold and edit articles yourself, contributing knowledge as you see fit in a collaborative way.

All of the text in Wikipedia, and most of the images and other content, is covered by the GNU Free Documentation License (GFDL). Contributions remain the property of their creators, while the GFDL license ensures the content is freely distributable and reproducible. (See the copyright notice and the content disclaimer for more information.)

wave

In May 2001, a wave of non-English Wikipedias was launched — in Catalan, Chinese, Dutch, Esperanto, French, German, Hebrew, Italian, Japanese, Portuguese, Russian, Spanish, and Swedish; these were soon joined by Arabic and Hungarian.[2] In September,[3] Polish was added and further commitment to the multilingual provision of Wikipedia was made. At the end of the year, Afrikaans, Norwegian, and Serbocroatian versions were announced.

was

There was considerable resistance on the part of Nupedia's editors and reviewers to the idea of associating Nupedia with a website in the wiki format, so the new project was given the name "Wikipedia" and launched on its own domain, wikipedia.com, on January 15 (now called "Wikipedia Day" by some users). The bandwidth and server (in San Diego) were donated by Wales. Other current and past Bomis employees who have worked on the project include Tim Shell, one of the cofounders of Bomis and its current CEO, and programmer Jason Richey. The domain was eventually changed to the present wikipedia.org when the nonprofit Wikimedia Foundation was launched as its new parent organization, prompting the use of a .org domain to denote its non-commercial nature. In March 2007, the word wiki became a newly recognized English word.[1]

For

About Wikipedia

Wikipedia history
For more details on this topic, see History of Wikipedia.
Wikipedia was founded as an offshoot of Nupedia, a now-abandoned project to produce a free encyclopedia. Nupedia had an elaborate system of peer review and required highly qualified contributors, but the writing of articles was slow. During 2000, Jimmy Wales, founder of Nupedia, and Larry Sanger, whom Wales had employed to work on the project, discussed ways of supplementing Nupedia with a more open, complementary project. Multiple sources are suggested for the idea that a wiki might allow members of the public to contribute material, and Nupedia's first wiki went online on January 10.

you

Because Wikipedia is an ongoing work to which, in principle, anybody can contribute, it differs from a paper-based reference source in important ways. In particular, older articles tend to be more comprehensive and balanced, while newer articles more frequently contain significant misinformation, unencyclopedic content, or vandalism. Users need to be aware of this to obtain valid information and avoid misinformation that has been recently added and not yet removed (see Researching with Wikipedia for more details). However, unlike a paper reference source, Wikipedia is continually updated, with the creation or updating of articles on topical events within seconds, minutes or hours, rather than months or years for printed encyclopedias.

If you have not done so, we invite you to take a few moments to read What Wikipedia is (and is not), so that you have an understanding of how to consult or contribute to Wikipedia. Further information on key topics appears below. If you cannot find what you are looking for, try the Frequently Asked Questions or see Where to ask questions. For help with editing and other issues, see Help:Contents.

Contents [hide]
1 About Wikipedia
1.1 Wikipedia history
1.2 Trademarks and copyrights
1.3 Wikipedia contributors
1.4 The Wikimedia Foundation
1.4.1 Employees
1.4.1.1 2008
2 Making the best use of Wikipedia
2.1 Exploring Wikipedia
2.2 Basic navigation in Wikipedia
2.3 Using Wikipedia as a research tool
2.4 Wikipedia vs. paper encyclopedias
2.5 Strengths, weaknesses, and article quality in Wikipedia
2.6 Disclaimers
3 Contributing to Wikipedia
3.1 Editing Wikipedia pages
3.2 Wikipedia content criteria
3.3 Editorial administration, oversight and management
3.4 Handling disputes and abuse
3.5 Editorial quality review
3.6 Technical attributes
4 Feedback and questions
4.1 Frequently asked questions (FAQ)
4.2 Giving feedback
4.3 Research help and similar questions
4.4 Community discussion
4.5 Contacting individual Wikipedia editors
5 Related versions and projects
6 Sister projects
7 See also
8 References
9 Further reading

Visitors

Visitors do not need specialized qualifications to contribute, since their primary role is to write articles that cover existing knowledge; this means that people of all ages and cultural and social backgrounds can write Wikipedia articles. Most of the articles can be edited by anyone with access to the Internet, simply by clicking the edit this page link. Anyone is welcome to add information, cross-references or citations, as long as they do so within Wikipedia's editing policies and to an appropriate standard. Substandard or disputed information is subject to removal. Users need not worry about accidentally damaging Wikipedia when adding or improving information, as other editors are always around to advise or correct obvious errors, and Wikipedia's software is carefully designed to allow easy reversal of editorial mistakes.

Wikipedia

Wikipedia is written collaboratively by volunteers from all around the world. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference Web sites attracting at least 684 million visitors yearly by 2008. There are more than 75,000 active contributors working on more than 10,000,000 articles in more than 250 languages. As of today, there are 2,412,241 articles in English; every day hundreds of thousands of visitors from around the world make tens of thousands of edits and create thousands of new articles to enhance the knowledge held by the Wikipedia encyclopedia. (See also: Wikipedia:Statistics).

extension

Hormonal Root Pruning Theory - in the new theory just like Ethylene, GA/BA are seen both to be induced by sugar and gas shortages in the roots, and to push sugar and gases, as well as minerals, water and the growth hormones out of the root cell causing a positive feedback loop resulting the emptying and death of the root cell.
Parallels to cell division - the theory perhaps even more controversially, asserts that just as both auxin and cytokinin seem to be needed before a plant cell divides, in the same way perhaps ethylene and GA/BA are needed before a cell would senesce.
Discussion of the complete mechanism - what really may occur is that because ethylene pushes out all nutrients out of the shoot cell including sugar and gases, eventually this causes a shortage of these nutrients in the organ (the shoot) which is supposed to procure them. This shortage leads to GA/BA synthesis in the rapidly declining shoot cell, and this simply adds fuel to the fire.
A Role for Abscisic Acid - finally a question may be to ask, what is the role of Abscisic Acid, the hormone which was first thought to be the primary mover in this department? According to author of the theory we have been discussing, ABA is induced when plant cells are encountering stress other than that of a nutrient shortage kind. In this case a senescing cell experiencing a drain of nutrients may experience a strain which causes it to produce ABA. Indeed it may not be that ethylene and GA/BA alone are needed for programmed cell senescence, but that all three are needed.
Similarly, auxin and cytokinin may not be enough for plant cell division alone, but a proposed compliment of ABA, SA, may be needed in addition.


[edit] See also
Ageing
Life extension
Senescence

[edit] External links
The Adaptive Reasons For And The Physiological Causes Of Senescence In Annual Plants
The Start at a General Theory of Plant Senescence

Ethylene

Shoot Pruning - it is now known that Ethylene induces the shedding of leaves much more than abscisic acid. ABA originally received its name because it was discovered to have a role in leaf abscission. Its role is now seen to be minor and only occurring in special cases.
Hormonal Shoot Pruning Theory - a new simple theory says that ethylene induces senescence in leaves due to a run away positive feedback mechanism. What supposedly happens is that ethylene is released by mostly mature leaves under water and or mineral shortages. The ethylene acts in mature leaf cells however, by pushing out minerals, water, sugar, gases and even the growth hormones auxin and cytokinin (and possibly salicylic acid in addition). This causes even more ethylene to be made until the leave is drained of all nutrients.
Root Pruning - the concept that plants prune the roots in the same kind of way as they abscise leaves, is not a well discussed topic among plant scientists, although the phenomena undoubtedly exists. If gibberellin and brassinosteroid are known to inhibit root growth it takes just a little imagination to assume they perform the same role as Ethylene does in the shoot, that is to prune the roots too.

Hormonal

[edit] Hormonal Induction of Senescence - Theory
There is not a lot of theory on how plants induce themselves to senesce, although it is pretty widely accepted that some of it is done hormonally. Plant scientists generally concentrate on Ethylene and abscisic acid as culprits in senescence, but neglect gibberellin and brassinosteroid which inhibits root growth if not causing actual root pruning. This is perhaps because roots are below the ground and thus harder to study.

part

Poor Productivity Reasons for Plant Self Pruning - The plant rarely prunes young dividing meristematic cells, but if a fully grown mature cell is no longer acquiring nutrients that it should acquire, then it is pruned.
Shoot Efficiency Self Pruning Reasons - For instance, presumably a mature shoot cell must on average produce enough sugar, and acquire enough oxygen and carbon dioxide to support both it and a similar sized root cell. Actually since plants are obviously interested in growing it is arguable, that the "directive" of the average shoot cell, is to "show a profit" and produce or acquire more than enough sugar and gases than is necessary to support both it and a similar sized root cell. If this "profit" isn't shown, the shoot cell is killed off and resources are redistributed to "promising" other young shoots or leaves in the hope that they will be more productive.
Root Efficiency Self Pruning Reasons - Similarly a mature root cell must acquire on average, more than enough minerals and water needed to support both it and a similar sized shoot cell that does not acquire water and minerals. If this doesn't happen, the root is killed off and resources sent to new young root candidates.
Shortage/ Need Based Reason for Plant Self Pruning - this is the other side of efficiency problems.
Shoot Shortages - If a shoot is not getting enough root derived minerals and water, the idea is that it will kill part of itself off, and send the resources to the root to make more roots.
Root Shortages - the idea here is that if the root is not getting enough shoot derived sugar and gases it will kill part of itself off and send resources the shoot, to allow more shoot growth
Clearly this is an oversimplification; in that it is arguable that some shoot and root cells serve other functions than to acquire nutrients. In these cases, whether they are pruned or not would be "calculated" by the plant using some other criteria. Also it is arguable that for example mature nutrient acquiring shoot cells would have to acquire more than enough shoot nutrients to support both it and its share of both shoot and root cells that don't acquire sugar and gases whether they are of a structural, reproductive, immature, or just plain of a root nature.

Self

[edit] Plant Self Pruning - Theory
There is a speculative hypothesis on how and why a plant induces part of itself to die off. The theory holds that leaves and roots are routinely pruned off during the growing season whether they are annual or perennial. This is done mainly to mature leaves and roots and this is done for two reasons, either both the leaves and roots that are pruned are no longer efficient enough nutrient acquisition-wise or that energy and resources are needed in another part of the plant because that part of the plant is faltering in its resource acquisition.

spac

Conversely, the perennial strategy may sometimes be the more effective survival strategy, because the plant has a head start every spring with growing points, roots, and stored energy that have survived through the winter. In trees for example, the structure can be built on year after year so that the tree and root structure can become larger, stronger, and capable of producing more fruit and seed than the year before, out-competing other plants for light, water, nutrients, and space.

benefit

The benefit of an annual strategy may be genetic diversity, as one set of genes does continue year after year, but a new mix is produced each year. Secondly, being annual may allow the plants a better survival strategy, since the plant can put most of its accumulated energy and resources into seed production rather than saving some for the plant to overwinter, which would limit seed production.

Annua

[edit] Annual Versus Perennial Benefits - Theory
Some plants have evolved into annuals, dying off at the end of each season and leaving seeds for the next, whereas closely related plants in the same family have evolved to live as perennials. This may be a programmed "strategy" for the plants.

rogra

[edit] Programmed senescence
Programmed Senscence seems to be heavily influenced by plant hormones. The hormones Abscisic Acid and Ethylene are accepted by most scientists as the main culprits, but at least one source, believes Gibberellins and Brassinosteroids are equally to blame.

Unp

[edit] Unprogrammed senescence - Plant Aging
Although there are differences between plants and other organisms, biological senescence in plants has similarities such as free radical damage and telomere shortening that apply as in other organisms.

autumn

The autumn senescence of Oregon Grape leaves is an example of programmed plant senescence.Contents [hide]
1 Unprogrammed senescence - Plant Aging
2 Programmed senescence
2.1 Annual Versus Perennial Benefits - Theory
2.2 Plant Self Pruning - Theory
2.3 Hormonal Induction of Senescence - Theory
3 See also
4 External links

just

Plant senescence is the study of aging in plants. It is a heavily studied subject just as it is in the other kingdoms of life. Plants, just like other forms of organisms seem to have both unintended and programmed aging. Leaf senescence is the cause of autumn leaf color in deciduous trees.

Source

Theories Are Beings With Life Cycles
- 1 The theory died out.

- 2 The theory is in the early stages of its development

- 3 This theory has been alive a long time.


Source Domain
beings, people, plants

Target Domain
theories

plants

These phenotypic changes may be analogous to other environmental stresses. We studied the interactions between insect herbivores and their inbred and outbred host plants in an attempt to determine if plant defense theory could accurately predict the effect of inbreeding on plant-insect interactions. Our work with the morning glory, Ipomoea hederaceae var. integriscula (Convolvulaceae), and its generalist and specialist herbivores suggests that plant defense theory may accurately predict the outcome of interactions between inbred plants and their herbivores. Inbred plants were more susceptible to generalist herbivores than specialist herbivores. Conversely, outbred plants were more susceptible to specialist herbivores and not generalist herbivores. In addition, specialist herbivores perform better on outbred plants than inbred plants and they choose to eat outbred plants when given a choice. Thus essential tenets of the Plant Stress/Plant Vigor hypotheses accurately predicted the effects of inbreeding on the outcome of interactions between I. hederaceae and its generalist and specialist herbivores.

Species 1: Lepidoptera Noctuidae Spodoptera exigua (beet armyworm)
Species 2: Coleoptera Chrysomelidae Chariodetlla bicolor (golden tortoise beetle)
Species 3: Coleoptera Chrysomelidae Deloyala guttata (mottled tortoise beetle)
Keywords: plant defense theory, plant stress


Back to Student Competition Ten-Minute Papers, Subsection Cd4. Behavior and Ecology
Back to Student Competition 10-minute Paper
Back to The 2002 ESA Annual Meeting and Exhibition

Helen

Helen Hull-Sanders and Micky D. Eubanks. Auburn University, Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn, AL
Two plant defense theories may predict plant-insect interactions involving inbred plants. The Plant Stress Hypothesis predicts that stressed plants will be more susceptible to generalist herbivores. The Plant Vigor Hypothesis predicts that specialist herbivores prefer and perform better when feeding on the most vigorous plants (low stress plants). Inbreeding (self-pollination) frequently occurs in many plant populations. Inbreeding typically results in broad, detrimental changes in plant morphology and physiology.

intact

Carnes Lord attributes the popular belief in this story to the fact that it provides "the most plausible explanation for the rapid eclipse of the Peripatetic school after the middle of the third century, and for the absence of widespread knowledge of the specialized treatises of Aristotle throughout the Hellenistic period, as well as for the sudden reappearance of a flourishing Aristotelianism during the first century B.C."[47] Lord voices a number of reservations concerning this story, however. First, the condition of the texts is far too good for them to have suffered considerable damage followed by Apellicon's inexpert attempt at repair. Second, there is "incontrovertible evidence," Lord says, that the treatises were in circulation during the time in which Strabo and Plutarch suggest they were confined within the cellar in Scepsis. Third, the definitive edition of Aristotle's texts seems to have been made in Athens some fifty years before Andronicus supposedly compiled his. And fourth, ancient library catalogues predating Andronicus' intervention list an Aristotelean corpus quite similar to the one we currently possess. Lord sees a number of post-Aristotelean interpolations in the Politics, for example, but is generally confident that the work has come down to us relatively intact.

As the influence of the falsafa grew in the West, in part due to Gerard of Cremona's translations and the spread of Averroism, the demand for Aristotle's works grew. William of Moerbeke translated a number of them into Latin. When Thomas Aquinas wrote his theology, working from Moerbeke's translations, the demand for Aristotle's writings grew and the Greek manuscripts returned to the West, stimulating a revival of Aristotelianism in Europe, and ultimately revitalizing European thought through Muslim influence in Spain to fan the embers of the Renaissance.

The loss of his works

The loss of his works
According to a distinction that originates with Aristotle himself, his writings are divisible into two groups: the "exoteric" and the "esoteric".[41] Most scholars have understood this as a distinction between works Aristotle intended for the public (exoteric), and the more technical works (esoteric) intended for the narrower audience of Aristotle's students and other philosophers who were familiar with the jargon and issues typical of the Platonic and Aristotelian schools. Another common assumption is that none of the exoteric works is extant - that all of Aristotle's extant writings are of the esoteric kind. Current knowledge of what exactly the exoteric writings were like is scant and dubious, though many of them may have been in dialogue form. (Fragments of some of Aristotle's dialogues have survived.) Perhaps it is to these that Cicero refers when he characterized Aristotle's writing style as "a river of gold";[42] it is hard for many modern readers to accept that one could seriously so admire the style of those works currently available to us.[43] However, some modern scholars have warned that we cannot know for certain that Cicero's praise was reserved specifically for the exoteric works; a few modern scholars have actually admired the concise writing style found in Aristotle's extant works.[44]

One major question in the history of Aristotle's works, then, is how were the exoteric writings all lost, and how did the ones we now possess come to us?[45] The story of the original manuscripts of the esoteric treatises is described by Strabo in his Geography and Plutarch in his Parallel Lives.[46] The manuscripts were left from Aristotle to his successor Theophrastus, who in turn willed them to Neleus of Scepsis. Neleus supposedly took the writings from Athens to Scepsis, where his heirs let them languish in a cellar until the first century BC, when Apellicon of Teos discovered and purchased the manuscripts, bringing them back to Athens. According to the story, Apellicon tried to repair some of the damage that was done during the manuscripts' stay in the basement, introducing a number of errors into the text. When Lucius Cornelius Sulla occupied Athens in 86 BC, he carried off the library of Apellicon to Rome, where they were first published in 60 BC by the grammarian Tyrranion of Amisus and then by philosopher Andronicus of Rhodes.

Aristotelian ethics

Ethics
Main article: Aristotelian ethics
Aristotle considered ethics to be a practical science, i.e., one mastered by doing rather than merely reasoning. Further, Aristotle believed that ethical knowledge is not certain knowledge (like metaphysics and epistemology) but is general knowledge. He wrote several treatises on ethics, including most notably, Nichomachean Ethics, in which he outlines what is commonly called virtue ethics.

Aristotle taught that virtue has to do with the proper function of a thing. An eye is only a good eye in so much as it can see, because the proper function of an eye is sight. Aristotle reasoned that man must have a function uncommon to anything else, and that this function must be an activity of the soul. Aristotle identified the best activity of the soul as eudaimonia: a happiness or joy that pervades the good life. Aristotle taught that to achieve the good life, one must live a balanced life and avoid excess. This balance, he taught, varies among different persons and situations, and exists as a golden mean between two vices - one an excess and one a deficiency.

Aristotle

Theory of biological being
However, for Charles Singer, "Nothing is more remarkable than [Aristotle's] efforts to [exhibit] the relationships of living things as a scala naturae"[21] Aristotle's History of Animals classified organisms in relation to a hierarchical "Ladder of Life" (scala naturae), placing them according to complexity of structure and function so that higher organisms showed greater vitality and ability to move.[22]

Aristotle believed that intellectual purposes, i.e., formal causes, guided all natural processes. Such a teleological view gave Aristotle cause to justify his observed data as an expression of formal design. Noting that "no animal has, at the same time, both tusks and horns," and "a single-hooved animal with two horns I have never seen," Aristotle suggested that Nature, giving no animal both horns and tusks, was staving off vanity, and giving creatures faculties only to such a degree as they are necessary. Noting that ruminants had a multiple stomachs and weak teeth, he supposed the first was to compensate for the latter, with Nature trying to preserve a type of balance.[23]

In a similar fashion, Aristotle believed that creatures were arranged in a graded scale of perfection rising from plants on up to man, the scala naturae or Great Chain of Being.[24] His system had eleven grades, arranged according "to the degree to which they are infected with potentiality", expressed in their form at birth. The highest animals laid warm and wet creatures alive, the lowest bore theirs cold, dry, and in thick eggs.

Aristotle also held that the level of a creature's perfection was reflected in its form, but not foreordained by that form.

He placed great importance on the type(s) of soul an organism possessed, asserting that plants possess a vegetative soul, responsible for reproduction and growth, animals a vegetative and a sensitive soul, responsible for mobility and sensation, and humans a vegetative, a sensitive, and a rational soul, capable of thought and reflection.[25]

Aristotle, in contrast to earlier philosophers, but in accordance with the Egyptians, placed the rational soul in the heart, rather than the brain.[26] Notable is Aristotle's division of sensation and thought, which generally went against previous philosophers, with the exception of Alcmaeon.[27]

His analysis of procreation is frequently criticized on the grounds that it presupposes an active, ensouling masculine element bringing life to an inert, passive, lumpen female element; it is on these grounds that Aristotle is considered by some feminist critics to have been a misogynist.[28]

Universals and particulars

[edit] Universals and particulars
Main article: Aristotle's theory of universals
Aristotle's predecessor, Plato, argued that all things have a universal form, which could be either a property, or a relation to other things. When we look at an apple, for example, we see an apple, and we can also analyze a form of an apple. In this distinction, there is a particular apple and a universal form of an apple. Moreover, we can place an apple next to a book, so that we can speak of both the book and apple as being next to each other.

Plato argued that there are some universal forms that are not a part of particular things. For example, it is possible that there is no particular good in existence, but "good" is still a proper universal form. Bertrand Russell is a contemporary philosopher that agreed with Plato on the existence of "uninstantiated universals".

Aristotle disagreed with Plato on this point, arguing that all universals are instantiated. Aristotle argued that there are no universals that are unattached to existing things. According to Aristotle, if a universal exists, either as a particular or a relation, then there must have been, must be currently, or must be in the future, something on which the universal can be predicated. Consequently, according to Aristotle, if it is not the case that some universal can be predicated to an object that exists at some period of time, then it does not exist.

One way for contemporary philosophers to justify this position is by asserting the eleatic principle.

In addition, Aristotle disagreed with Plato about the location of universals. As Plato spoke of the world of the forms, a location where all universal forms subsist, Aristotle maintained that universals exist within each thing on which each universal is predicated. So, according to Aristotle, the form of apple exists within each apple, rather than in the world of the forms.

flute

Substance, potentiality and actuality
Aristotle examines the concept of substance (ousia) in his Metaphysics, Book VII and he concludes that a particular substance is a combination of both matter and form. As he proceeds to the book VIII, he concludes that the matter of the substance is the substratum or the stuff of which it is composed, e.g. the matter of the house are the bricks, stones, timbers etc., or whatever constitutes the potential house. While the form of the substance, is the actual house, namely ‘covering for bodies and chattels’ or any other differentia (see also predicables). The formula that gives the components is the account of the matter, and the formula that gives the differentia is the account of the form.[16]

With regard to the change (kinesis) and its causes now, as he defines in his Physics and On Generation and Corruption 319b-320a, he distinguishes the coming to be from 1. growth and diminution, which is change in quantity 2. locomotion, which is change in space and 3. alteration, which is change in quality. The coming to be is a change where nothing persists of which the resultant is a property. In that particular change he introduces the concept of potentiality (dynamis) and actuality (entelecheia) in association with the matter and the form.

Referring to potentiality, this is what a thing is capable of doing, or being acted upon, if it is not prevented by something else. For example, the seed of a plant in the soil is potentially (dynamei) plant, and if is not prevented by something, it will become a plant. Potentially beings can either 'act' (poiein) or 'be acted upon' (paschein), which can be either innate or learned. For example, the eyes possess the potentiality of sight (innate - being acted upon), while the capability of playing the flute can be possessed by learning (exercise - acting).

Actuality is the fulfillment of the end of the potentiality. Because the end (telos) is the principle of every change, and for the sake of the end exists potentiality, therefore actuality is the end. Referring then to our previous example, we could say that actuality is when the seed of the plant becomes a plant.

“ For that for the sake of which a thing is, is its principle, and the becoming is for the sake of the end; and the actuality is the end, and it is for the sake of this that the potentiality is acquired. For animals do not see in order that they may have sight, but they have sight that they may see.”[17]

In conclusion, the matter of the house is its potentiality and the form is its actuality. The formal cause (aitia) then of that change from potential to actual house, is the reason (logos) of the house builder and the final cause is the end, namely the house itself. Then Aristotle proceeds and concludes that the actuality is prior to potentiality in formula, in time and in substantiality.

With this definition of the particular substance (i.e., matter and form), Aristotle tries to solve the problem of the unity of the beings, e.g., what is that makes the man one? Since, according to Plato there are two Ideas: animal and biped, how then is man a unity? However, according to Aristotle, the potential being (matter) and the actual one (form) are one and the same thing.[18

realm

Chance and spontaneity
Spontaneity and chance are causes of effects. Chance as an incidental cause lies in the realm of accidental things. It is "from what is spontaneous" (but note that what is spontaneous does not come from chance). For a better understanding of Aristotle's conception of "chance" it might be better to think of "coincidence": Something takes place by chance if a person sets out with the intent of having one thing take place, but with the result of another thing (not intended) taking place. For example: A person seeks donations. That person may find another person willing to donate a substantial sum. However, if the person seeking the donations met the person donating, not for the purpose of collecting donations, but for some other purpose, Aristotle would call the collecting of the donation by that particular donator a result of chance. It must be unusual that something happens by chance. In other words, if something happens all or most of the time, we cannot say that it is by chance.

There is also more specific kind of chance, which Aristotle names "luck", that can only apply to human beings, since it is in the sphere of moral actions. According to Aristotle, luck must involve choice (and thus deliberation), and only humans are capable of deliberation and choice. "What is not capable of action cannot do anything by chance".[15]

Causality

Causality, The Four Causes
The material cause is that from which a thing comes into existence as from its parts, constituents, substratum or materials. This reduces the explanation of causes to the parts (factors, elements, constituents, ingredients) forming the whole (system, structure, compound, complex, composite, or combination), a relationship known as the part-whole causation.
The formal cause tells us what a thing is, that any thing is determined by the definition, form, pattern, essence, whole, synthesis or archetype. It embraces the account of causes in terms of fundamental principles or general laws, as the whole (i.e., macrostructure) is the cause of its parts, a relationship known as the whole-part causation.
The efficient cause is that from which the change or the ending of the change first starts. It identifies 'what makes of what is made and what causes change of what is changed' and so suggests all sorts of agents, nonliving or living, acting as the sources of change or movement or rest. Representing the current understanding of causality as the relation of cause and effect, this covers the modern definitions of "cause" as either the agent or agency or particular events or states of affairs.
The final cause is that for the sake of which a thing exists or is done, including both purposeful and instrumental actions and activities. The final cause or telos is the purpose or end that something is supposed to serve, or it is that from which and that to which the change is. This also covers modern ideas of mental causation involving such psychological causes as volition, need, motivation, or motives, rational, irrational, ethical, all that gives purpose to behavior.
Additionally, things can be causes of one another, causing each other reciprocally, as hard work causes fitness and vice versa, although not in the same way or function, the one is as the beginning of change, the other as the goal. (Thus Aristotle first suggested a reciprocal or circular causality as a relation of mutual dependence or influence of cause upon effect). Moreover, Aristotle indicated that the same thing can be the cause of contrary effects; its presence and absence may result in different outcomes.

Aristotle marked two modes of causation: proper (prior) causation and accidental (chance) causation. All causes, proper and incidental, can be spoken as potential or as actual, particular or generic. The same language refers to the effects of causes, so that generic effects assigned to generic causes, particular effects to particular causes, operating causes to actual effects. Essentially, causality does not suggest a temporal relation between the cause and the effect.

All further investigations of causality will consist of imposing the favorite hierarchies on the order causes, such as final > efficient > material > formal (Thomas Aquinas), or of restricting all causality to the material and efficient causes or to the efficient causality (deterministic or chance) or just to regular sequences and correlations of natural phenomena (the natural sciences describing how things happen instead of explaining the whys and wherefores).

claimed

His writings provide an account of many scientific observations, a mixture of precocious accuracy and curious errors. For example, in his History of Animals he claimed that human males have more teeth than females.[11] In a similar vein, John Philoponus, and later Galileo, showed by simple experiments that Aristotle's theory that the more massive object falls faster than a less massive object is incorrect.[12] On the other hand, Aristotle refuted Democritus's claim that the Milky Way was made up of "those stars which are shaded by the earth from the sun's rays," pointing out (correctly, even if such reasoning was bound to be dismissed for a long time) that, given "current astronomical demonstrations" that "the size of the sun is greater than that of the earth and the distance of the stars from the earth many times greater than that of the sun, then...the sun shines on all the stars and the earth screens none of them."[13]

In places, Aristotle goes too far in deriving 'laws of the universe' from simple observation and over-stretched reason. Today's scientific method assumes that such thinking without sufficient facts is ineffective, and that discerning the validity of one's hypothesis requires far more rigorous experimentation than that which Aristotle used to support his laws.

Aristotle also had some scientific blind spots. He posited a geocentric cosmology that we may discern in selections of the Metaphysics, which was widely accepted up until the 1500s. From the 3rd century to the 1500s, the dominant view held that the Earth was the center of the universe (geocentrism).

Since he was perhaps the philosopher most respected by European thinkers during and after the Renaissance, these thinkers often took Aristotle's erroneous positions as given, which held back science in this epoch.[14] However, Aristotle's scientific shortcomings should not mislead one into forgetting his great advances in the many scientific fields. For instance, he founded logic as a formal science and created foundations to biology that were not superseded for two millennia. Moreover, he introduced the fundamental notion that nature is composed of things that change and that studying such changes can provide useful knowledge of underlying constants.

Like

For more details on this topic, see Aristotle's theory of universals.
Like his teacher Plato, Aristotle's philosophy aims at the universal. Aristotle, however, found the universal in particular things, which he called the essence of things, while Plato finds that the universal exists apart from particular things, and is related to them as their prototype or exemplar. For Aristotle, therefore, philosophic method implies the ascent from the study of particular phenomena to the knowledge of essences, while for Plato philosophic method means the descent from a knowledge of universal Forms (or ideas) to a contemplation of particular imitations of these. For Aristotle, "form" still refers to the unconditional basis of phenomena but is "instantiated" in a particular substance (see Universals and particulars, below). In a certain sense, Aristotle's method is both inductive and deductive, while Plato's is essentially deductive from a priori principles.[10]

In Aristotle's terminology, "natural philosophy" is a branch of philosophy examining the phenomena of the natural world, and included fields that would be regarded today as physics, biology and other natural sciences. In modern times, the scope of philosophy has become limited to more generic or abstract inquiries, such as ethics and metaphysics, in which logic plays a major role. Today's philosophy tends to exclude empirical study of the natural world by means of the scientific method. In contrast, Aristotle's philosophical endeavors encompassed virtually all facets of intellectual inquiry.

In the larger sense of the word, Aristotle makes philosophy coextensive with reasoning, which he also would describe as "science". Note, however, that his use of the term science carries a different meaning than that covered by the term "scientific method". For Aristotle, "all science (dianoia) is either practical, poetical or theoretical" (Metaphysics 1025b25). By practical science, he means ethics and politics; by poetical science, he means the study of poetry and the other fine arts; by theoretical science, he means physics, mathematics and metaphysics.

If logic (or "analytics") is regarded as a study preliminary to philosophy, the divisions of Aristotelian philosophy would consist of: (1) Logic; (2) Theoretical Philosophy, including Metaphysics, Physics, Mathematics, (3) Practical Philosophy and (4) Poetical Philosophy.

In the period between his two stays in Athens, between his times at the Academy and the Lyceum, Aristotle conducted most of the scientific thinking and research for which he is renowned today. In fact, most of Aristotle's life was devoted to the study of the objects of natural science. Aristotle’s metaphysics contains observations on the nature of numbers but he made no original contributions to mathematics. He did, however, perform original research in the natural sciences, e.g., botany, zoology, physics, astronomy, chemistry, meteorology, and several other sciences.

Aristotle's writings on science are largely qualitative, as opposed to quantitative. Beginning in the sixteenth century, scientists began applying mathematics to the physical sciences, and Aristotle's work in this area was deemed hopelessly inadequate. His failings were largely due to the absence of concepts like mass, velocity, force and temperature. He had a conception of speed and temperature, but no quantitative understanding of them

Organon

Main article: Organon
What we today call Aristotelian logic, Aristotle himself would have labeled "analytics". The term "logic" he reserved to mean dialectics. Most of Aristotle's work is probably not in its original form, since it was most likely edited by students and later lecturers. The logical works of Aristotle were compiled into six books in about the early 1st century AD:

Categories
On Interpretation
Prior Analytics
Posterior Analytics
Topics
On Sophistical Refutations
The order of the books (or the teachings from which they are composed) is not certain, but this list was derived from analysis of Aristotle's writings. It goes from the basics, the analysis of simple terms in the Categories, to the study of more complex forms, namely, syllogisms (in the Analytics) and dialectics (in the Topics and Sophistical Refutations). There is one volume of Aristotle's concerning logic not found in the Organon, namely the fourth book of Metaphysics

earlier

Aristotle "says that 'on the subject of reasoning' he 'had nothing else on an earlier date to speak of'".[6] However, Plato reports that syntax was devised before him, by Prodikos of Keos, who was concerned by the correct use of words. Logic seems to have emerged from dialectics; the earlier philosophers made frequent use of concepts like reductio ad absurdum in their discussions, but never truly understood the logical implications. Even Plato had difficulties with logic; although he had a reasonable conception of a deduction system, he could never actually construct one and relied instead on his dialectic.[7] Plato believed that deduction would simply follow from premises, hence he focused on maintaining solid premises so that the conclusion would logically follow. Consequently, Plato realized that a method for obtaining conclusions would be most beneficial. He never succeeded in devising such a method, but his best attempt was published in his book Sophist, where he introduced his division method.[8]

Aristotle

Aristotle was born in Stageira, Chalcidice in 384 BC. His father, Nicomachus was the personal physician to King Amyntas of Macedon. Aristotle was trained and educated as a member of the aristocracy. At about the age of eighteen, he went to Athens to continue his education at Plato's Academy. Aristotle remained at the academy for nearly twenty years, not leaving until after Plato's death in 347 BC. He then traveled with Xenocrates to the court of Hermias of Atarneus in Asia Minor. While in Asia, Aristotle traveled with Theophrastus to the island of Lesbos, where together they researched the botany and zoology of the island. Aristotle married Hermias' daughter (or niece) Pythias. She bore him a daughter, whom they named Pythias. Soon after Hermias' death, Aristotle was invited by Philip of Macedon to become tutor to Alexander the Great.

After spending several years tutoring the young Alexander the Great, Aristotle returned to Athens. By 335 BC, he established his own school there, known as the Lyceum. Aristotle conducted courses at the school for the next twelve years. While in Athens, his wife Pythias died, and Aristotle became involved with Herpyllis of Stageira, who bore him a son whom he named after his father, Nicomachus. According to the Suda, he also had an eromenos, Palaephatus of Abydus.[2]

It is during this period in Athens when Aristotle is believed to have composed many of his works. Aristotle wrote many dialogues, only fragments of which survived. The works that have survived are in treatise form and were not, for the most part, intended for widespread publication, as they are generally thought to be lecture aids for his students. His most important treatises include Physics, Metaphysics, Nicomachean Ethics, Politics, De Anima (On the Soul) and Poetics. These works, although connected in many fundamental ways, vary significantly in both style and substance.

Aristotle not only studied almost every subject possible at the time, but made significant contributions to most of them. In physical science, Aristotle studied anatomy, astronomy, economics, embryology, geography, geology, meteorology, physics and zoology. In philosophy, he wrote on aesthetics, ethics, government, metaphysics, politics, psychology, rhetoric and theology. He also studied education, foreign customs, literature and poetry. His combined works constitute a virtual encyclopedia of Greek knowledge. It has been suggested that Aristotle was probably the last person to know everything there was to be known in his own time.[3] Upon Alexander's death, anti-Macedonian sentiment in Athens once again flared. Eurymedon the hierophant denounced Aristotle for not holding the gods in honor. Aristotle fled the city to his mother's family estate in Chalcis, explaining, "I will not allow the Athenians to sin twice against philosophy,"[4] a reference to Athens's prior trial and execution of Socrates. However, he died in Euboea of natural causes within the year (in 322 BC). Aristotle left a will and named chief executor his student Antipater, in which he asked to be buried next to his wife. Some people believe that Aristotle died because Athens thought he had something to do with Alexander the Great's death. [5]

Carolus

divided the living world between animals and plants, and this was followed by Carolus Linnaeus (Carl von Linné), in the first hierarchical classification. Since then biologists have begun emphasizing evolutionary relationships, and so these groups have been restricted somewhat. For instance, microscopic protozoa were originally considered animals because they move, but are now treated separately.

In Linnaeus's original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, the Chordata, whereas the various other forms have been separated out. The above lists represent our current understanding of the group, though there is some variation from source to source

Model organisms

Model organisms
Main articles: Model organism and Animal testing
Because of the great diversity found in animals, it is more economical for scientists to study a small number of chosen species so that connections can be drawn from their work and conclusions extrapolated about how animals function in general. Because they are easy to keep and breed, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans have long been the most intensively studied metazoan model organisms, and were among the first lifeforms to be genetically sequenced. This was facilitated by the severely reduced state of their genomes, but the double-edged sword here is that with many genes, introns and linkages lost, these ecdysozoans can teach us little about the origins of animals in general. The extent of this type of evolution within the superphylum will be revealed by the crustacean, annelid, and molluscan genome projects currently in progress. Analysis of the starlet sea anemone genome has emphasised the importance of sponges, placozoans, and choanoflagellates, also being sequenced, in explaining the arrival of 1500 ancestral genes unique to the Eumetazoa.[21]

An analysis of the homoscleromorph sponge Oscarella carmela also suggests that the last common ancestor of sponges and the eumetazoan animals was more complex than previously assumed.[22]

Other model organisms belonging to the animal kingdom include the mouse (Mus musculus) and zebrafish (Danio rerio}.

Lophotrochozoa

The Lophotrochozoa include two of the most successful animal phyla, the Mollusca and Annelida.[11][12] The former includes animals such as snails, clams, and squids, and the latter comprises the segmented worms, such as earthworms and leeches. These two groups have long been considered close relatives because of the common presence of trochophore larvae, but the annelids were considered closer to the arthropods,[13] because they are both segmented. Now this is generally considered convergent evolution, owing to many morphological and genetic differences between the two phyla.[14]

The Lophotrochozoa also include the Nemertea or ribbon worms, the Sipuncula, and several phyla that have a fan of cilia around the mouth, called a lophophore.[15] These were traditionally grouped together as the lophophorates.[16] but it now appears they are paraphyletic,[17] some closer to the Nemertea and some to the Mollusca and Annelida.[18][19] They include the Brachiopoda or lamp shells, which are prominent in the fossil record, the Entoprocta, the Phoronida, and possibly the Bryozoa or moss animals.[20]

Ecdysozoa

The Ecdysozoa are protostomes, named after the common trait of growth by moulting or ecdysis. The largest animal phylum belongs here, the Arthropoda, including insects, spiders, crabs, and their kin. All these organisms have a body divided into repeating segments, typically with paired appendages. Two smaller phyla, the Onychophora and Tardigrada, are close relatives of the arthropods and share these traits.

The ecdysozoans also include the Nematoda or roundworms, the second largest animal phylum. Roundworms are typically microscopic, and occur in nearly every environment where there is water. A number are important parasites. Smaller phyla related to them are the Nematomorpha or horsehair worms, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.

The remaining two groups of protostomes are sometimes grouped together as the Spiralia, since in both embryos develop with spiral cleavage

Deuterostomes

Deuterostomes

Superb Fairy-wren, Malurus cyaneusDeuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract. However, in protostomes the initial opening (the archenteron) develops into the mouth, and an anus forms separately. In deuterostomes this is reversed. In most protostomes, cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes it forms through invagination of the endoderm, called enterocoelic pouching. Deuterostomes also have a dorsal, rather than a ventral, nerve chord and their embryos undergo different cleavage.

All this suggests the deuterostomes and protostomes are separate, monophyletic lineages. The main phyla of deuterostomes are the Echinodermata and Chordata. The former are radially symmetric and exclusively marine, such as starfish, sea urchins, and sea cucumbers. The latter are dominated by the vertebrates, animals with backbones. These include fish, amphibians, reptiles, birds, and mammals.

In addition to these, the deuterostomes also include the Hemichordata or acorn worms. Although they are not especially prominent today, the important fossil graptolites may belong to this group.

The Chaetognatha or arrow worms may also be deuterostomes, but more recent studies suggest protostome affinities.

Porifera

The sponges (Porifera) were long thought to have diverged from other animals early. As mentioned above, they lack the complex organization found in most other phyla. Their cells are differentiated, but in most cases not organized into distinct tissues. Sponges are sessile and typically feed by drawing in water through pores. Archaeocyatha, which have fused skeletons, may represent sponges or a separate phylum. However, a phylogenomic study in 2008 of 150 genes in 21 genera[7] revealed that it is the Ctenophora or comb jellies which are the basal lineage of animals, at least among those 21 phyla. The authors speculate that sponges—or at least those lines of sponges they investigated—are not so primitive, but may instead be secondarily simplified.

Among the other phyla, the Ctenophora and the Cnidaria, which includes sea anemones, corals, and jellyfish, are radially symmetric and have digestive chambers with a single opening, which serves as both the mouth and the anus. Both have distinct tissues, but they are not organized into organs. There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, these animals are sometimes called diploblastic. The tiny Placozoans are similar, but they do not have a permanent digestive chamber.

The remaining animals form a monophyletic group called the Bilateria. For the most part, they are bilaterally symmetric, and often have a specialized head with feeding and sensory organs. The body is triploblastic, i.e. all three germ layers are well-developed, and tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is also an internal body cavity called a coelom or pseudocoelom. There are exceptions to each of these characteristics, however - for instance adult echinoderms are radially symmetric, and certain parasitic worms have extremely simplified body structures.

Genetic studies have considerably changed our understanding of the relationships within the Bilateria. Most appear to belong to two major lineages: the Deuterostomes and Protostomes, which includes the Ecdysozoa, Platyzoa, and Lophotrochozoa. In addition, there are a few small groups of bilaterians with relatively similar structure that appear to have diverged before these major groups. These include the Acoelomorpha, Rhombozoa, and Orthonectida. The Myxozoa, single-celled parasites that were originally considered Protozoa, are now believed to have developed from the Bilateria as well.

Origin and fossil record

Origin and fossil record
Animals are generally considered to have evolved from a flagellated eukaryote. Their closest known living relatives are the choanoflagellates, collared flagellates that have a morphology similar to the choanocytes of certain sponges. Molecular studies place animals in a supergroup called the opisthokonts, which also include the choanoflagellates, fungi and a few small parasitic protists. The name comes from the posterior location of the flagellum in motile cells, such as most animal spermatozoa, whereas other eukaryotes tend to have anterior flagella.

The first fossils that might represent animals appear towards the end of the Precambrian, around 610 million years ago, and are known as the Ediacaran or Vendian biota. These are difficult to relate to later fossils, however. Some may represent precursors of modern phyla, but they may be separate groups, and it is possible they are not really animals at all. Aside from them, most known animal phyla make a more or less simultaneous appearance during the Cambrian period, about 542 million years ago. It is still disputed whether this event, called the Cambrian explosion, represents a rapid divergence between different groups or a change in conditions that made fossilization possible. However some paleontologists and geologists would suggest that animals appeared much earlier than previously thought, possibly even as early as 1 billion years ago. Trace fossils such as tracks and burrows found in Tonian era strata in India indicate the presence of triploblastic worm like metazoans roughly as large (about 5mm wide) and complex as earthworms.[6] In addition during the beginning of the Tonian period around 1 billion years ago (roughly the same time that the trace fossils previously discussed in this article date back to) there was a decrease in Stromatolite diversity which may indicate the appearance of grazing animals during this time as Stromatolites also increased in diversity shortly after the end-Ordovician and end-Permian rendered large amounts of grazing marine animals extinct and decreased shortly after their populations recovered. However some other scientists doubt that these fossils are authentic and have suggested these trace fossils are just the result of natural processes such as erosion.[citation needed]

zygote

Many animals are also capable of asexual reproduction. This may take place through parthenogenesis, where fertile eggs are produced without mating, or in some cases through fragmentation.

A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers - an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.

Most animals grow by indirectly using the energy of sunlight. Plants use this energy to convert sunlight into simple sugars using a process known as photosynthesis. Starting with the molecules carbon dioxide (CO2) and water (H2O), photosynthesis converts the energy of sunlight into chemical energy stored in the bonds of glucose (C6H12O6) and releases oxygen (O2). These sugars are then used as the building blocks which allow the plant to grow. When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal. They are either used directly to help the animal grow, or broken down, releasing stored solar energy, and giving the animal the energy required for motion. This process is known as glycolysis.

Animals who live close to hydrothermal vents and cold seeps on the ocean floor are not dependent on the energy of sunlight. Instead, chemosynthetic archaea and eubacteria form the base of the food chain.

Structure

Structure
With a few exceptions, most notably the sponges (Phylum Porifera), animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissue, which sends and processes signals. There is also typically an internal digestive chamber, with one or two openings. Animals with this sort of organization are called metazoans, or eumetazoans when the former is used for animals in general.

All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms like plants and fungi have cells held in place by cell walls, and so develop by progressive growth. Also, unique to animal cells are the following intercellular junctions: tight junctions

several

Characteristics
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and usually multicellular[2] (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic,[3] generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls.[4] All animals are motile,[5] if only at certain life stages. In most animals, embryos pass through a blastula stage, which is a characteristic exclusive to animals

Etymology

Etymology
The word "animal" comes from the Latin word animale, neuter of animalis, and is derived from anima, meaning vital breath or soul. In everyday colloquial usage, the word usually refers to non-human animals. The biological definition of the word refers to all members of the Kingdom Animalia. Therefore, when the word "animal" is used in a biological context, humans are included.[1]

Animal

Animal
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"Animalia" redirects here. For the book, see Animalia (book).
For other uses, see Animal (disambiguation).
Animals
Fossil range: Ediacaran - Recent


Clockwise from top-left: Loligo vulgaris (a mollusk), Chrysaora quinquecirrha (a cnidarian), Aphthona flava (an arthropod), Eunereis longissima (an annelid), and Panthera tigris (a chordate).
Scientific classification
Domain: Eukaryota

(unranked) Opisthokonta

Kingdom: Animalia
Linnaeus, 1758

Phyla
Subkingdom Parazoa
Porifera
Subkingdom Eumetazoa
Placozoa
Radiata (unranked)
Ctenophora
Cnidaria
Bilateria (unranked)
Orthonectida
Rhombozoa
Acoelomorpha
Chaetognatha
Superphylum Deuterostomia
Chordata
Hemichordata
Echinodermata
Xenoturbellida
Vetulicolia †
Protostomia (unranked)
Superphylum Ecdysozoa
Kinorhyncha
Loricifera
Priapulida
Nematoda
Nematomorpha
Lobopodia †
Onychophora
Tardigrada
Arthropoda
Superphylum Platyzoa
Platyhelminthes
Gastrotricha
Rotifera
Acanthocephala
Gnathostomulida
Micrognathozoa
Cycliophora
Superphylum Lophotrochozoa
Sipuncula
Hyolitha †
Nemertea
Phoronida
Bryozoa
Entoprocta
Brachiopoda
Mollusca
Annelida
Echiura

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile - they can move spontaneously and independently. Animals are heterotrophs - they are dependent on other organisms (e.g. plants) for sustenance.

Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago.