My favourite quotes.

*Ask the experimenters why they experiment on animals, and the answer is:  "Because the animals are like us."  Ask the experimenters why it is morally okay to experiment on animals, and the answer is:  "Because the animals are not like us."  Animal experimentation rests on a logical contradiction. 

*God loved the birds and invented trees.  Man loved the birds and invented cages.

*We have enslaved the rest of the animal creation, and have treated our distant cousins in fur and feathers so badly that beyond doubt, if they were able to formulate a religion, they would depict the Devil in human form. 


*The question is not, "Can they reason?" nor, "Can they talk?" but rather, "Can they suffer?"

*Man is the only creature that consumes without producing.  He does not give milk, he does not lay eggs, he is too weak to pull the plough, he cannot run fast enough to catch rabbits.  Yet he is lord of all the animals.

*Life is life - whether in a cat, or dog or man.  There is no difference there between a cat or a man.  The idea of difference is a human conception for man's own advantage.

*The woods were made for the hunters of dreams,
The brooks for the fishers of song;
To the hunters who hunt for the gunless game
The streams and the woods belong.

*God made all the creatures and gave them our love and our fear,
To give sign, we and they are His children, one family here.

*As long as man eats animals how can cruelty to animals be removed.

*Animals are such agreeable friends - they ask no questions, they pass no criticisms.

*Man is a dog's idea of what God should be.

*When a dog barks at the moon, then it is religion; but when he barks at strangers, it is patriotism! 

*Dogs laugh, but they laugh with their tails.

*God gives every bird its food, but He does not throw it into its nest.

Wildlife conservation

Wildlife conservation is the preservation, protection, or restoration of wildlife and their environment, especially in relation to endangered and vulnerable species. All living non-domesticated animals, even if bred, hatched or born in captivity, are considered wild animals. Wildlife represents all the non-cultivated and non-domesticated animals living in their natural habitats. Our world has many unique and rare animals, birds and reptiles. However the pressure of growing population in different parts of the world has led to the increasing need of using land for human habitations and agriculture. This has led to the reduced habitat of many wild animals.

Major threats to wildlife

Major threats to wildlife can be categorized as below:

• Habitat Loss: Fewer natural wildlife habitat areas remain each year. Moreover, the habitat that remains has often been degraded to bear little resemblance to the natural wild areas which existed in the past.

• Climate Change: Because many types of plants and animals have specific habitat requirements, climate change could cause disastrous loss of wildlife species. A slight drop or rise in average rainfall will translate into large seasonal changes. Hibernating mammals, reptiles, amphibians and insects are harmed and disturbed. Plants and wildlife are sensitive to moisture change so, they will be harmed by any change in the moisture level.

• Pesticides & Toxic Chemicals: Pesticides are deliberately spread to make the environment toxic to certain plants, insects, and rodents, so it should not be surprising that other plants and wildlife are deliberately harmed at the same time. In addition many chemical pollutants are toxic to wildlife, such as PCBs, mercury, petrolium by-products, solvents, antifreeze, etc.

• Hunting and Poaching: Unregulated hunting and poaching causes a major threat to wildlife. Along with this, mismanagement of forest department and forest guards triggers this problem.
• Natural Phenomenon: Floods, earthquakes, volcanoes, lightning, forest fires

The North American Model of Wildlife Conservation

The North American Model of Wildlife Conservation is the most successful conservation model in world^[1]. It has its origins in 19th century conservation movements, the near extinction of several species of wildlife (including the American Bison) and the rise of sportsmen with the middle class^[2][3]. Beginning in the 1860s sportsmen began to organize and advocate for the preservation of wilderness areas and wildlife. The North American Model of Wildlife Conservation rests on two basic principles – fish and wildlife are for the non-commercial use of citizens, and should be managed such that they are available at optimum population levels forever. These core principles are elaborated upon in the seven major tenets of the model.

• Public Trust Doctrine: In the North American Model, wildlife is held in the public trust. This means that fish and wildlife are held by the public through state and federal governments. In other words, though an individual may own the land up which wildlife resides, that individual does not own said wildlife. Instead, the wildlife is owned by all citizens. With origins in Roman times and English Common law, the public trust doctrine has at its heart the 1842 Supreme Court ruling Martin V. Waddell^[4][5].

• Regulated commerce in wildlife: Under the North American Model, wildlife exist outside the market, removing any direct commercial value from wild game as they and the meat thereof cannot be bought or sold. Certain products such as antlers and fur may, however, be bought and sold. The end of market hunting was a major step in the restoration of North American species. By removing the pressure of market hunting allowed game and fish species to recover and eventually be taken by hunters and anglers at sustainable levels^[6].

• Hunting and angling laws are created through the public process: Through democratic representation, citizens create the policies that regulate, conserve, and manage wildlife within the United States and Canada. The creation and implementation of wildlife and natural resource management policy is an open and public process^[7].

• Opportunity for all, funded by all: All citizens have a right to hunting and fishing. Additionally the management of fish and wildlife is funded through the sale of licenses and in the taxation of hunting and fishing equipment. Additional funding comes from state and federal budgets, but the bulk of funding is through these sources^[8].

• Non-frivolous use: Under the North American Model, the killing of game must be done only for food, fur, self-defense, and the protection of property (including livestock). In other words, it is broadly regarded as unlawful and unethical to kill fish or wildlife (even with a license) without making all reasonable effort to retrieve and make reasonable use of the resource^[9][10].

• Wildlife as an international resource: As wildlife do exist only within fixed political boundaries, effective management of these resources must be done internationally, through treaties and the cooperation of management agencies^[11][12].

• Scientific Management: Effective management of wildlife and other natural resources must be based on continuous and sound scientific research^[13][14].

Government Involvement

The Wildlife Conservation Act was enacted by the Government of India in 1972.

Behavioral enrichment to any animal

Behavioral enrichment, also called environmental enrichment is an 'animal husbandry principle that seeks to enhance the quality of captive animal care by identifying and providing the environmental stimuli necessary for optimal psychological and physiological wellbeing'.^[1] The goal of environmental enrichment is to improve or maintain an animal's physical and psychological health by increasing range or number of species-specific behaviours, increasing positive utilisation of the captive environment, preventing or reducing the frequency of abnormal behaviours such as stereotypical behaviors, and increasing the individual's ability to cope with captive challenges. In principle, enrichment can be beneficial to any relatively intelligent animal, including mammals, birds, and even octopuses.^[2]
Environmental enrichment may be offered to any animal in captivity, including:

• Captive animals in zoos and related institutions.^[3]
• Animals in sanctuaries.^[4]
• Animals used for research
• Animals used for companionship, e.g. dogs, cats, rabbits, etc.

Types of enrichment

Any novel stimulus which evokes an animal's interest can be considered enriching, including natural and artificial objects, scents, novel foods, and different methods of preparing foods (for example, frozen in ice). Most enrichment stimulus can be divided into six groups:

• Sensory, this category stimulates animals' senses: visual, olfactory, auditory, tactile, and taste.
• Feeding, this is how keepers make feeding time fun and challenging. Different methods of food presentation encourage animals to think and work for their food as they would in the wild.
• Manipulative Toys, these are items that can be manipulated in some way via hands, feet, tail, horns, head, mouth etc. simply for investigation and exploratory play.
• Environmental, this category enables the keeper to enhance the animals' zoo habitat with opportunities that change or add complexity to the environment.
• Social, the opportunities to interact with other animals.
• Training, training animals with positive reinforcement.

Puzzles that require an animal to solve simple problems in order to access food or other rewards are considered enrichment. Additionally food collecting and/or gathering contributes to behavioral enrichment and provides occupation. Quite elaborate systems of food presentation (dead rats) have been developed (e.g. in Switzerland for wild cats), where computer programmed various mechanic devices allow the animals in the enclosure to search for prey as in their natural environment. An animal's environment may also be enriched by the presence of other animals of the same or different species. A stimulus can be considered enriching even if the animal's reaction to it is negative, such as with unpleasant scents, although stimuli that evoke extreme stress or fear should be avoided, as well as stimuli that can be harmful to the animal. Enrichment can also be auditory which may include animal sounds and music.
Many people also believe that a behavior modification program (animal training) can also be enriching to a captive animal. Also the use of behavioral training, as another method of behavioral enrichment, has often contributed to the animals well-being as well as allowed zoos to improve dramatically their ability to care for animals, while reducing animal stress and increasing safety for both keeper and animal during care procedures.
Enclosures in modern zoos are often designed with enrichment in mind. For example, the Denver Zoo's exhibit Predator Ridge allows different African carnivore species to rotate among several enclosures, providing the animals with a larger environment and exposing them to each others' scents.

Zoo

A zoological garden, zoological park, menagerie, or zoo is a facility in which animals are confined within enclosures, displayed to the public, and in which they may also be bred.
The term zoological garden refers to zoology, the study of animals, a term deriving from the Greek zōon (ζῷον, "animal") and lógos (λóγος, "study"). The abbreviation "zoo" was first used of the London Zoological Gardens, which opened for scientific study in 1828 and to the public in 1847.^[1] The number of major animal collections open to the public around the world now exceeds 1,000, around 80 percent of them in cities.^[2]

Appearance and type

Zoo animals usually live in enclosures that attempt to replicate their natural habitats, for the benefit of the animals and the visitors. They may have special buildings for nocturnal animals, with dim white or red lighting used during the day, so the animals will be active when visitors are there, and brighter lights at night to help them sleep. Special climate conditions are created for animals living in radical environments, such as penguins. Special enclosures for birds, insects, reptiles, fish, and other aquatic life forms have also been developed. Some zoos have walk-through exhibits where visitors enter enclosures of non-aggressive species, such as lemurs, marmosets, birds, lizards, and turtles. Visitors are asked to keep to paths and avoid showing or eating foods that the animals might snatch.

Petting zoos

A petting zoo, also called children's farms or children's zoos, features a combination of domestic animals and wild species that are docile enough to touch and feed. To ensure the animals' health, the food is supplied by the zoo, either from vending machines or a kiosk nearby.

Animal Theme Parks

 An animal theme park is a combination of an amusement park and a zoo, mainly for entertaining and commercial purposes. Marine mammal parks such as Sea World and Marineland are more elaborate dolphinariums keeping whales, and containing additional entertainment attractions. Another kind of animal theme park contains more entertainment and amusement elements than the classical zoo, such as a stage shows, roller coasters, and mythical creatures. Some examples are Busch Gardens Tampa Bay in Tampa, Florida, Disney's Animal Kingdom in Orlando, Florida, Flamingo Land in North Yorkshire, England and Six Flags Discovery Kingdom in Vallejo, California .

surplus animals

For every animal caught in the wild, several more are killed in the process. Therefore, the breeding of animals within zoos is encouraged.^[22] Eric Baratay and Elisabeth Hardouin-Fugier of the Université Jean-Moulin, Lyon, say that the overall "stock turnover" of animals is one-fifth to one-fourth over the course of a year—with three-quarters of apes dying in captivity within the first twenty months. They say that the high mortality rate is the reason for the "massive scale of importations."^[30]
The downside to breeding the animals in captivity is that thousands of them are placed on "surplus lists" each year, and sold to circuses, animal merchants, auctions, pet owners, and game farms. The San Jose Mercury News conducted a two-year study that suggested of the 19,361 mammals who left accredited zoos in the U.S. between 1992 and 1998, 7,420 (38 percent) went to dealers, auctions, hunting ranches, unaccredited zoos and individuals, and game farms.^[31]
Zoos have advertised surplus animals in the Animal Finders' Guide, a newsletter in which the owners of hunting ranches post notices of sales and auctions.^[32] Matthew Scully writes that many hunters prefer killing animals from zoos because they make better-looking trophies; the mane of a zoo lion will tend to be cleaner than that of a wild one.^[32] In one case, a zoo owner named William Hampton was found to have been buying animals and systematically slaughtering them in order to sell their skins, heads, and pelts as trophies.^[33]
Animals who breed frequently, such as deer, tiger, and lions may be killed for their meat; Nuremberg zoo's deputy director, Helmut Mägdefrau, has said, "If we cannot find good homes for the animals, we kill them and use them as feed."^[34] Other animals may be sold to smaller zoos with poor conditions. PETA cites the example of Edith, a chimpanzee found in a concrete pit in a roadside zoo called the Amarillo Wildlife Refuge in Texas. She had been born in the Saint Louis Zoo, but had been sold just after her third birthday, and for the next 37 years was passed around five other facilities before landing in the roadside zoo.^[35]
It was alleged in March 2008 that hundreds of the Berlin Zoo's 23,000 animals are missing, amid allegations that they have been slaughtered, and that some tigers and leopards were sent to China to make drugs for traditional Chinese medicine. Claudia Hämmerling, a Green Party politician, said she had evidence that four Asian black bears and a hippopotamus were taken from Berlin to go to a new home, but were transported instead to Wortel in Belgium, which The Guardian reports has no zoo, but does have a slaughterhouse. The zoo's director, Bernhard Blaszkiewitz, replied that the allegations were "untruths, half-truths and lies."^[34]

 

Cruelty to animals

Cruelty to animals or animal abuse is the infliction of suffering or harm upon animals, other than humans, for purposes other than self-defense. More narrowly, it can be harm for specific gain, such as killing animals for food or for their fur. Diverging viewpoints are held by jurisdictions throughout the world.
Broadly speaking, there are two approaches to the issue. The animal welfare position holds that there is nothing inherently wrong with using animals for human purposes, such as food, clothing, entertainment, and research, but that it should be done in a humane way that minimizes unnecessary pain and suffering. Animal rights theorists criticize this position, arguing that the words "unnecessary" and "humane" are subject to widely differing interpretations, and that the only way to ensure protection for animals is to end their status as property, and to ensure that they are never used as commodities. Laws concerning animal cruelty are designed to prevent needless cruelty to animals, rather than killing for other aims such as food, or they concern species not eaten as food in the country involved, such as those regarded as pets.

In law

Many jurisdictions around the world have enacted statutes which forbid cruelty to some animals but these vary by country and in some cases by the use or practice

Australia

In Australia, many states have enacted legislation outlawing cruelty to animals, however, it is argued that welfare laws do not adequately extend to production animals.^[1] Whilst police maintain an overall jurisdiction in prosecution of criminal matters, in many states officers of the RSPCA and other animal welfare charities are accorded authority to investigate and prosecute animal cruelty offenses.

Japan

Animal experiments are regulated by the 2000 Law for the Humane Treatment and Management of Animals, which was amended in 2006.^[2] This law requires those using animals to follow the principles outlined in the 3Rs and use as few animals as possible, and cause minimal distress and suffering. Regulation is at a local level based on national guidelines, but there are no governmental inspections of institutions and no reporting requirement for the numbers of animals used.^[3]

Hong Kong

As of 2010, Hong Kong has supplemented or replaced the laws against cruelty with a positive approach using laws that specify how animals should be treated.^[13] The government department primarily responsible for animal welfare in Hong Kong is the Agriculture, Fisheries and Conservation Department (AFCD).
Laws enforced by the AFCD include these:

• the Prevention of Cruelty to Animals Ordinance (also enforced by the police)
• the Public Health (Animals and Birds) Ordinance (including regulations for licences imposed on livestock keepers and animal traders and a Code of Standards for Licensed Animal Traders)
• the Dogs and Cats Ordinance
• the Pounds Ordinance
• the Rabies Ordinance
• the Wild Animals Protection Ordinance

In addition, the Food and Environmental Hygiene Department (FEHD) does the following:

• enforces the Public Health and Municipal Services Ordinance, which includes regulations for slaughterhouses and wet markets
• publishes a Code of Practice for the Welfare of Food Animals (which describes their transport)
• publishes Operational Guidelines for the Welfare of Food Animals at Slaughterhouses

The Department of Health does the following:

• enforces the Animals (Control of Experiments) Ordinance.
• publishes a Code of Practice for the Care and Use of Animals for Experimental Purposes

As of 2006, Hong Kong has a law titled "Prevention of Cruelty to Animals Ordinance", with a maximum 3 year imprisonment and fines of HKD$200,000.^[14]

Taiwan

The Taiwanese Animal Protection Act was passed in 1998, imposing fines up to NT$250,000 for cruelty. Criminal penalties for animal cruelty were enacted in 2007, including a maximum of 1 year imprisonment.^[15]

Europe

Germany, Switzerland, Sweden, and Austria have all banned battery cages for egg-laying hens. The entire European Union is phasing out battery cages by 2012.^[21] It is also illegal in many parts of Europe to declaw a cat.^[22]

Germany

In Germany, killing animals or causing significant pain (or prolonged or repeated pain) to them is punishable by imprisonment of up to three years or a financial penalty.^[23] If the animal is of foreign origin, the act may also be punishable as criminal damage.^[24]

Italy

Acts of cruelty against animals can be punished with imprisonment, for a minimum of three months up to a maximum of three years, and with a fine ranging from a minimum of 3.000,00 Euro to a maximum of 160.000,00 Euro, as for the law n°189/2004.^[25] The law was passed mainly to crush the phenomenon of dog fighting, which in Italy is a clandestine blood sport fully controlled by organized crime.

United Kingdom

In the United Kingdom, cruelty to animals is a criminal offence for which one may be jailed for up to 51 weeks and may be fined up to £20,000.^[26]
On August 18, 1911, the House of Commons introduced the Protection of Animals Act 1911 (c.27) following lobbying by the Royal Society for the Prevention of Cruelty to Animals (RSPCA). The maximum punishment was 6 months of "hard labour" with a fine of 25 pounds.^[27]
In the London Police Act 1839, "fighting or baiting Lions, Bears, Badgers, Cocks, Dogs, or other Animals" was prohibited in London, with a penalty of up to one month imprisonment, with possible hard labour, or up to five pounds. The law laid numerous restrictions on how, when, and where animals could be driven, wagons unloaded, etc.. It also prohibited owners from letting mad dogs run loose and gave police the right to destroy any dog suspected of being rabid or any dog bitten by a suspected rabid dog. The same law prohibited the use of dogs for drawing carts.^[28] Up until then, dogs were used for delivering milk, bread, fish, meat, fruit, vegetables, animal food (the cat's-meat man), and other items for sale and for collecting refuse (the rag-and-bone man).^[29][30] As Nigel Rothfels notes, the prohibition against dogs pulling carts in or near London caused most of the dogs to be killed by their owners^[31] as they went from being contributors to the family income to unaffordable expenses. Cart dogs were replaced by people with handcarts.^[32] About 150,000 dogs were killed or abandoned. Erica Fudge quotes Hilda Kean:^[31]

At the heart of nineteenth-century animal welfare campaigns is the middle-class desire not to be able to see cruelty.

—Hilda Kean, Animal Rights, 1998^[33]

The Protection of Animals Act 1911^[34] extended the ban on draft dogs to the rest of the kingdom. As many as 600,000 dogs were killed or abandoned.

United States

The primary federal law relating to animal care and conditions in the US is the Animal Welfare Act of 1966, amended in 1970, 1976, 1985, 1990, 2002 and 2007. It is the only Federal law in the United States that regulates the treatment of animals in research, exhibition, transport, and by dealers. Other laws, policies, and guidelines may include additional species coverage or specifications for animal care and use, but all refer to the Animal Welfare Act as the minimum acceptable standard.^[38]
The AWA has been criticized by animal rights groups for excluding birds, rats and mice bred for research, and animals raised for food or fiber as well as all cold-blooded animals.^[39]
The Animal Legal Defense Fund releases an annual report ranking the animal protection laws of every state based on their relative strength and general comprehensiveness. In 2008's report, the top five states for their strong anti-cruelty laws were California, Illinois, Maine, Michigan, and Oregon. The five states with the weakest animal cruelty laws were Arkansas, Idaho, Kentucky, Mississippi, and North Dakota.^[40]
In Massachusetts and New York, agents of humane societies and associations may be appointed as special officers to enforce statutes outlawing animal cruelty.^[41]
In 2004, a Florida legislator proposed a ban on "cruelty to bovines," stating: "A person who, for the purpose of practice, entertainment, or sport, intentionally fells, trips, or otherwise causes a cow to fall or lose its balance by means of roping, lassoing, dragging, or otherwise touching the tail of the cow commits a misdemeanor of the first degree."^[42] The proposal did not become law.^[42]
In the United States, ear cropping, tail docking, the Geier Hitch, rodeo sports, and other acts are legal and sometimes condoned. Penalties for cruelty can be minimal, if pursued. Currently, 46 of the 50 states have enacted felony penalties for certain forms of animal abuse.^[43] However, in most jurisdictions, animal cruelty is most commonly charged as a misdemeanor offense. In one recent California case, a felony conviction for animal cruelty could theoretically net a 25 year to life sentence due to their three-strikes law, which increases sentences based on prior felony convictions.^[44]
In 2003, West Hollywood, California passed an ordinance banning declawing of house cats.^[45] In 2007, Norfolk, Virginia passed legislation only allowing the procedure for medical reasons.^[46] However, most jurisdictions allow the procedure.

TV & film making

Animal cruelty has long been an issue with the art form of filmmaking, with even some big-budget Hollywood films receiving criticism for allegedly harmful—and sometimes lethal—treatment of animals during production. One of the most infamous examples of animal cruelty in film was Michael Cimino's legendary flop Heaven's Gate, in which numerous animals were brutalized and even killed during production. Cimino allegedly killed chickens and bled horses from the neck to gather samples of their blood to smear on actors for Heaven's Gate, and also allegedly had a horse blown up with dynamite while shooting a battle sequence, the shot of which made it into the film. After the release of the film Reds, the star and director of the picture, Warren Beatty apologized for his Spanish film crew's use of tripwires on horses while filming a battle scene, when Beatty wasn't present. Tripwires were used against horses when Rambo III and The Thirteenth Warrior were being filmed. An ox was sliced nearly in half during production of Apocalypse Now, while a donkey was bled to death for dramatic effect for the film Manderlay, in a scene later cut from the film.
Cruelty in film exists in movies outside the United States. There is a case of cruelty to animals in the South Korean film The Isle, according to its director Kim Ki-Duk.^[65] In the film, a real frog is skinned alive while fish are mutilated. Several animals were killed for the camera in the controversial Italian film Cannibal Holocaust.^[66] The images in the film include the slow and graphic beheading and ripping apart of a turtle, a monkey being beheaded and its brains being consumed by natives and a spider being chopped apart. In fact, Cannibal Holocaust was only one film in a collective of similarly themed movies (cannibal films) that featured unstaged animal cruelty. Their influences were rooted in the films of Mondo filmmakers, which sometimes contained similar content. In several countries, such as the UK, Cannibal Holocaust was only allowed for release with most of the animal cruelty edited out.
More recently, the video sharing site YouTube has been criticized for hosting thousands of videos of real life animal cruelty, especially the feeding of one animal to another for the purposes of entertainment and spectacle. Although some of these videos have been flagged as inappropriate by users, YouTube has generally declined to remove them, unlike videos which include copyright infringement.^[67][68]
The Screen Actors Guild (SAG) has contracted with the American Humane Association (AHA) for monitoring of animal use during filming or while on the set.^[69] Compliance with this arrangement is voluntary and only applies to films made in the United States. Films monitored by the American Humane Association may bear one of their end-credit messages. Many productions, including those made in the US, do not advise AHA or SAG of animal use in films, so there is no oversight.^[70]
Simulations of animal cruelty exist on television, too. On the September 23, 1999 edition of WWE Smackdown!, a plot line had professional wrestler Big Boss Man trick fellow wrestler Al Snow into appearing to eat his pet chihuahua Pepper.^[71][72]

Circuses

The use of animals in the circus has been controversial since animal welfare groups have documented instances of animal cruelty during the training of performing animals. The Humane Society of the United States has documented multiple cases of abuse and neglect,^[73] and cite several reasons for opposing the use of animals in circuses, including confining enclosures, lack of regular veterinary care, abusive training methods and lack of oversight by regulating bodies.^[74] Animal trainers have argued that some criticism is not based in fact, including beliefs that animals are 'hurt' by being shouted at, that caging is cruel and common, and the harm caused by the use of whips, chains or training implements.^[75]
In 2009, Bolivia passed legislation banning the use of any animals, wild or domestic, in circuses. The law states that circuses "constitute an act of cruelty." Circus operators had one year from the bill's passage on July 1, 2009 to comply.^[76]
In 2010, Lebanese animal rights groups became enraged when it was learned that wild performing animals belonging to the Monte Carlo Circus were transported from Egypt to Lebanon without being provided with food and water.^[77]

Restrictions

Following the campaign, new regulations were enacted that prohibit the use of animals in circuses in Israel. Finland and Singapore have restricted the use of animals in entertainment. The UK and Scottish Parliaments have committed to ban certain wild animals in travelling circuses and approximately 200 local authorities in the UK have banned all animal acts on council land.^{[citation needed]} Animal acts are still very popular throughout much of Europe, the Americas and Asia. In the United States animal welfare standards are overseen by the United States Department of Agriculture under provisions of the Animal Welfare Act. Efforts to ban circus animals in cities like Denver, Colorado have been rejected by voters. Some circuses now present animal-free acts.^[78]

List of animal advocacy parties

In recent years, several political parties were founded that have as their main goal the improvement of animal welfare and the recognition of animal rights:

• The Human Environment Animal Welfare Party (in German: Partei Mensch Umwelt Tierschutz, in short: Tierschutzpartei) was founded in Germany, in 1993.
• The Party for the Animals (in Dutch: Partij voor de Dieren) was founded in the Netherlands, in 2002. It is represented in parliament with two seats by Marianne Thieme and Esther Ouwehand.
• The Animal Alliance Environment Voters Party of Canada was formed by the Animal Alliance of Canada and its Environment Voters subsidiary in 2005.
• The Party Against Bullfighting, Cruelty and Mistreatment to Animals (in Spanish: PACMA, Partido Antitaurino Contra el Maltrato Animal).
• The Animals Count party was launched in the UK in 2006.
• The Animal Protection Party was founded in England in 2008.
• The Partito Animalista Italiano was founded in Italy in 2008.
• The Animal Justice Party was founded in Australia in 2010.
• The Animal Rights Party USA was founded in the United States in 2011. It is modeled after the Dutch Party for the Animals (PvdD). Like the PvdD, it is a political animal welfare organization that focuses on improving animal welfare and animal rights, and solving related environmental problems.

List of animal welfare groups

Animal welfare groups endorse the responsible use of animals to satisfy certain human needs. These range from companionship and sport, to uses which involve the taking of life, such as for food, clothing and medical research. Animal welfare means ensuring that all animals used by humans have their basic needs fulfilled in terms of food, shelter and health, and that they experience no unnecessary suffering in providing for human needs. Unlike animal rights groups, animal welfare groups do not argue that animals should never be used, or kept as property, by human beings. Nor do any animal welfare groups advocate violence. These groups tend to seek legal, social and financial strategies.
The following is a list of animal welfare groups. For animal rights, see the list of animal rights groups.

• Alley Cat Allies
• Animal Chaplains
• Animal Defenders International (ADI)
• Animal Legal Defense Fund (ALDF)
• Animal Protection Institute (API)
• Animal Rights Party USA
• American Society for the Prevention of Cruelty to Animals (ASPCA)
• Animal Welfare Institute (AWI)
• Anti-Cruelty Society (in Chicago in the US) ("to prevent cruelty to animals")
• Arizona Humane Society
• Bat Conservation International
• Bat World Sanctuary
• British Divers Marine Life Rescue (BDMLR)
• Born Free Foundation
• The Blue Cross
• Cats Protection (formerly Cats Protection League)
• Compassion In World Farming (CIWF)
• Dogs Trust (formerly National Canine Defence League)
• Ducks Unlimited
• Eurogroup for Animals
• Friends of Animals (FoA)
• Grey2K USA
• Houston Society for the Prevention of Cruelty to Animals (HSPCA)
• International Fund for Animal Welfare (IFAW)
• International Primate Protection League (IPPL)
• It's Meow or Never For Ferals (IMON For Ferals) [1]
• The Greyhound Protection League (GPL)
• Kathmandu Animal Treatment Centre
• League Against Cruel Sports (previously also known as LACS)
• Marine Connection
• Michigan Humane Society
• National Animal Welfare Trust
• National Anti-Vivisection Society (NAVS)
• New England Anti-Vivisection Society (NEAVS)
• ORCA (animal welfare organisation in Serbia)
• Party for the Animals USA
• Pennsylvania Society for the Prevention of Cruelty to Animals
• People's Dispensary for Sick Animals (PDSA)
• The Retired Greyhound Trust (RGT)
• Royal Society for the Prevention of Cruelty to Animals (RSPCA)
• Royal New Zealand Society for the Prevention of Cruelty to Animals (RNZSPCA)
• Sanctuary One
• Scottish SPCA (SSPCA)
• Society for Animal Protective Legislation (SAPL)
• Society for Protection of Animal Rights in Egypt
• Shark Trust
• WDCS (Whale and Dolphin Conservation Socitey)
• Wolf Preservation Foundation (WPF)
• World Society for the Protection of Animals (WSPA)
• Chinese Animal Protection Network (CAPN)

Animal law

Animal law is a combination of statutory and case law in which the nature – legal, social or biological – of nonhuman animals is an important factor. Animal law encompasses companion animals, wildlife, animals used in entertainment and animals raised for food and research. The emerging field of animal law is often analogized to the environmental law movement 30 years ago.

Approaches to animal law

Animal law issues encompass a broad spectrum of approaches—from philosophical explorations of the rights of animals to pragmatic discussions about the rights of those who use animals, who has standing to sue when an animal is harmed in a way that violates the law, and what constitutes legal cruelty.^[1] Animal law permeates and affects most traditional areas of the law – including tort, contract, criminal and constitutional law. Examples of this intersection include:

• Animal custody disputes in divorce or separations.^[2]
• Veterinary malpractice cases.
• Housing disputes involving “no pets” policies and discrimination laws.
• Damages cases involving the wrongful death or injury to a companion animal.^[3]
• Enforceable trusts for companions being adopted by states across the country.^[4]
• Criminal law encompassing domestic violence and anti-cruelty laws.

Recent legal changes influenced by animal rights activists

Regarding the campaign to change the status of animals as property, the animal rights activists have seen success in several countries. In 1992, Switzerland amended its constitution to recognize animals as beings and not things.^[13] However, in 1999 the Swiss constitution was completely rewritten. A decade later, Germany guaranteed rights to animals in a 2002 amendment to its constitution, becoming the first European Union member to do so.^[13][14][15] The German Civil Code had been amended correspondingly in 1997. The amendment, however, has not had much impact in German legal practice yet.^{[citation needed]}
The greatest success of the animal rights activists has certainly been the granting of basic rights to five great ape species in New Zealand in 1999. Their use is now forbidden in research, testing or teaching.^[16](It should be noted that the UK government banned experiments on great apes in 1986 ^[17]). Some other countries have also banned or severely restricted the use of non-human great apes in research.
The Seattle-based Great Ape Project (GAP) — founded by Australian philosopher Peter Singer, the author of Animal Liberation, widely regarded as the founding philosophical work of the animal liberation movement^[18] — is campaigning for the United Nations to adopt its Declaration on Great Apes, which would see chimpanzees, bonobos, gorillas and orang-utans included in a "community of equals" with human beings. The declaration wants to extend to the non-human apes the protection of three basic interests: the right to life, the protection of individual liberty, and the prohibition of torture ^[19] (see also Great ape personhood).

Animal welfare

Animal welfare is the physical and psychological well-being of animals.^[1] The term animal welfare can also mean human concern for animal welfare or a position in a debate on animal ethics and animal rights.^[2] Welfare is measured by indicators such as behavior, physiology, animal choices, longevity, production and reproduction.^[3]
Systematic concern for animal welfare can be based on awareness that non-human animals are sentient and that consideration should be given to their well-being, especially when they are used by humans.^[4] These concerns can include how animals are killed for food, how they are used for scientific research, how they are kept as pets, and how human activities affect the survival of endangered species.
An ancient object of concern in some civilizations, animal welfare began to take a larger place in western public policy in 19th-century Britain. Today it is a significant focus of interest or activity in veterinary science, in ethics, and in animal welfare organizations.
There are two forms of criticism of the concept of animal welfare, coming from diametrically opposite positions. One view, dating back centuries, asserts that animals are not consciously aware and hence are unable to experience poor welfare. The other view is based on the animal rights position that animals should not be regarded as property and any use of animals by humans is unacceptable. Some authorities thus treat animal welfare and animal rights as two opposing positions.^[2] Accordingly, some animal right proponents argue that the perception of better animal welfare facilitates continued and increased exploitation of animals.^[5][6] Others see the increasing concern for animal welfare as incremental steps towards animal rights.

Definitions

In animal ethics, the term animal welfare often means animal welfarism.
In Saunders Comprehensive Veterinary Dictionary, animal welfare is defined as "the avoidance of abuse and exploitation of animals by humans by maintaining appropriate standards of accommodation, feeding and general care, the prevention and treatment of disease and the assurance of freedom from harassment, and unnecessary discomfort and pain."^[7]
Donald Broom defines the welfare of an animal as "its state as regards its attempts to cope with its environment. This state includes how much it is having to do to cope, the extent to which it is succeeding in or failing to cope, and its associated feelings." He states that "Welfare will vary over a continuum from very good to very poor and studies of welfare will be most effective if a wide range of measures is used."^[8]
Yew-Kwang Ng defines animal welfare in terms of welfare economics: "Welfare biology is the study of living things and their environment with respect to their welfare (defined as net happiness, or enjoyment minus suffering). Despite difficulties of ascertaining and measuring welfare and relevancy to normative issues, welfare biology is a positive science."^[9]

[

Animal suffering

Singer writes that commentators on all sides of the debate now accept that animals suffer and feel pain, although it was not always so. Bernard Rollin, a philosopher and professor of animal sciences, writes that Descartes' influence continued to be felt until the 1980s. Veterinarians trained in the U.S. before 1989 were taught to ignore pain, he writes, and at least one major veterinary hospital in the 1960s did not stock narcotic analgesics for animal pain control. In his interactions with scientists, he was often asked to "prove" that animals are conscious, and to provide "scientifically acceptable" evidence that they could feel pain.^[87]
According to Singer, scientific publications have made it clear over the last two decades that the majority of researchers do believe animals suffer and feel pain, though it continues to be argued that their suffering may be reduced by an inability to experience the same dread of anticipation as humans, or to remember the suffering as vividly.^[88] In the most recent edition of Animal Liberation, Singer cites research indicating that animal impulses, emotions, and feelings are located in the diencephalon, a region well developed in mammals and birds.^[89] He also relies on the work of Richard Sarjeant. Sarjeant pointed out that non-human animals possess anatomical complexity of the cerebral cortex and neuroanatomy that is nearly identical to that of the human nervous system, arguing that, "[e]very particle of factual evidence supports the contention that the higher mammalian vertebrates experience pain sensations at least as acute as our own. To say that they feel less because they are lower animals is an absurdity; it can easily be shown that many of their senses are far more acute than ours."^[90]
The problem of animal suffering, and animal consciousness in general, arises primarily because animals have no language, leading scientists to argue that it is impossible to know when an animal is suffering. This situation may change as increasing numbers of chimps are taught sign language, although skeptics question whether their use of it portrays real understanding. Singer writes that, following the argument that language is needed to communicate pain, it would often be impossible to know when humans are in pain. All we can do is observe pain behavior, he writes, and make a calculated guess based on it. As Ludwig Wittgenstein argued, if someone is screaming, clutching a part of their body, moaning quietly, or apparently unable to function, especially when followed by an event we believe would cause pain in ourselves, that is in large measure what it means to be in pain.^[91] Singer argues that there is no reason to suppose animal pain behavior would have a different meaning.

1824: Society for the Prevention of Cruelty to Animals

Richard Martin soon realized that magistrates did not take the Martin Act seriously, and that it was not being reliably enforced. Several members of parliament decided to form a society to bring prosecutions under the Act. The Reverend Arthur Broome, a Balliol man who had recently become the vicar of Bromley-by-Bow, arranged a meeting in Old Slaughter's Coffee House in St. Martin's Lane, a London café frequented by artists and actors. The group met on June 16, 1824, and included a number of MPs: Richard Martin, Sir James Mackintosh, Sir Thomas Buxton, William Wilberforce, and Sir James Graham, who had been an MP, and who became one again in 1826. They decided to form a "Society instituted for the purpose of preventing cruelty to animals," or the Society for the Prevention of Cruelty to Animals, as it became known. It determined to send men to inspect Smithfield Market, where livestock had been sold since the 10th century, as well as slaughterhouses, and the practices of coachmen toward their horses.^[33] The Society became the Royal Society in 1840, when it was granted a royal charter by Queen Victoria, herself strongly opposed to vivisection.^[38]
Noel Molland writes that, in 1824, Catherine Smithies, an anti-slavery activist, set up an SPCA youth wing called the Bands of Mercy. It was a children's club modeled on the Temperance Society's Bands of Hope, which were intended to encourage children to campaign against drinking and gambling. The Bands of Mercy were similarly meant to encourage a love of animals.^[39] Molland writes that some of its members responded with more enthusiasm than Smithies intended, and became known for engaging in direct action against hunters by sabotaging their rifles, although Kim Stallwood writes that he has never been able to find solid evidence to support this.^[40] Whether the story is true or apocryphal, the idea of the youth group was revived by Ronnie Lee in 1972, when he and Cliff Goodman set up the Band of Mercy as a militant, anti-hunting guerrilla group, which slashed hunters' vehicles' tires and smashed their windows. In 1976, some of the same activists, sensing that the Band of Mercy name sounded too accommodating, founded the Animal Liberation Front.^[39]

Moral status of animals in the ancient world

The 21st-century debates about how humans should treat animals can be traced to the ancient world. The idea that the use of animals by humans—for food, clothing, entertainment, and as research subjects—is morally acceptable, springs mainly from two sources. First, there is the idea of a divine hierarchy based on the theological concept of "dominion," from Genesis (1:20–28), where Adam is given "dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth." Although the concept of dominion need not entail property rights, it has been interpreted over the centuries to imply ownership. There is also the idea that animals are inferior because they lack rationality and language, and as such are worthy of less consideration than humans, or even none.^[6] Springing from this is the idea that individual animals have no separate moral identity: a pig is simply an example of the class of pigs, and it is to the class, not to the individual, that human stewardship should be applied. This leads to the argument that the use of individual animals is acceptable so long as the species is not threatened with extinction.^[7]

Animal rights

Animal rights, also known as animal liberation, is the idea that the most basic interests of non-human animals should be afforded the same consideration as the similar interests of human beings. Advocates approach the issue from different philosophical positions, ranging from the protectionist side of the movement, presented by philosopher Peter Singer—with a utilitarian focus on suffering and consequences, rather than on the concept of rights—to the abolitionist side, represented by law professor Gary Francione, who argues that animals need only one right: the right not to be property. Despite the different approaches, advocates broadly agree that animals should be viewed as non-human persons and members of the moral community, and should not be used as food, clothing, research subjects, or entertainment.^[3]
The idea of awarding rights to animals has the support of legal scholars such as Alan Dershowitz and Laurence Tribe of Harvard Law School. Animal rights is routinely covered in universities in philosophy or applied ethics courses, and as of spring 2010 animal law was taught in 125 law schools in the United States and Canada. Toronto lawyer Clayton Ruby argued in 2008 that the movement had reached the stage the gay rights movement was at 25 years earlier.^[4]
Critics of the idea argue that animals are unable to enter into a social contract or make moral choices, and for that reason cannot be regarded as possessors of rights, a position summed up by the philosopher Roger Scruton, who wrote in 2000 that only humans have duties and therefore only humans have rights. There has also been criticism, including from within the animal rights movement itself, of certain forms of animal rights activism, in particular the destruction of fur farms and animal laboratories by the Animal Liberation Front. A parallel argument is that there is nothing inherently wrong with using animals as resources so long there is no unnecessary suffering, a view known as the animal welfare position.^[5]

Animal

Etymology

The word "animal" comes from the Latin word animalis, meaning "having breath".^[1] In everyday colloquial usage, the word usually refers to non-human animals.^[2] Frequently, only closer relatives of humans such as mammals and other vertebrates are meant in colloquial use.^[3] The biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects and humans.^[4]

Characteristics

Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and mostly multicellular,^[5] which separates them from bacteria and most protists. They are heterotrophic,^[6] generally digesting food in an internal chamber, which separates them from plants and algae.^[7] They are also distinguished from plants, algae, and fungi by lacking rigid cell walls.^[8] All animals are motile,^[9] if only at certain life stages. In most animals, embryos pass through a blastula stage,^[10] which is a characteristic exclusive to animals.

Structure

With a few exceptions, most notably the sponges (Phylum Porifera) and Placozoa, animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals. Typically, there is also an internal digestive chamber, with one or two openings.^[11] Animals with this sort of organization are called metazoans, or eumetazoans when the former is used for animals in general.^[12]
All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins.^[13] This may be calcified to form structures like shells, bones, and spicules.^[14] During development, it forms a relatively flexible framework^[15] 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.^[11] Also, unique to animal
cells are the following intercellular junctions: tight junctions, gap junctions, and desmosomes.^[16]

Reproduction and development

Nearly all animals undergo some form of sexual reproduction.^[17] They have a few specialized reproductive cells, which undergo meiosis to produce smaller, motile spermatozoa or larger, non-motile ova.^[18] These fuse to form zygotes, which develop into new individuals.^[19]
Many animals are also capable of asexual reproduction.^[20] This may take place through parthenogenesis, where fertile eggs are produced without mating, budding, or fragmentation.^[21]
A zygote initially develops into a hollow sphere, called a blastula,^[22] which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge.^[23] In most other groups, the blastula undergoes more complicated rearrangement.^[24] It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers — an external ectoderm and an internal endoderm.^[25] In most cases, a mesoderm also develops between them.^[26] These germ layers then differentiate to form tissues and organs.^[27]

Food and energy sourcing

Main article: Animal nutrition

All animals are heterotrophs, meaning that they feed directly or indirectly on other living things.^[28] They are often further subdivided into groups such as carnivores, herbivores, omnivores, and parasites.^[29]
Predation is a biological interaction where a predator (a heterotroph that is hunting) feeds on its prey (the organism that is attacked).^[30] Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of the prey.^[31] The other main category of consumption is detritivory, the consumption of dead organic matter.^[32] It can at times be difficult to separate the two feeding behaviours, for example, where parasitic species prey on a host organism and then lay their eggs on it for their offs pring to feed on its decaying corpse. Selective pressures imposed on one another has led to an evolutionary arms race between prey and predator, resulting in various antipredator adaptations.^[33]
Most animals feed indirectly from 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.^[11] When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal.^[34] 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.^[35] This process is known as glycolysis.^[36]
Animals living close to hydrothermal vents and cold seeps on the ocean floor are not dependent on the energy of sunlight.^[37] Instead chemosynthetic archaea and bacteria form the base of the food chain.^[38]

O

Animals are generally considered to have evolved from a flagellated eukaryote.^[40] Their closest known living relatives are the choanoflagellates, collared flagellates that have a morphology similar to the choanocytes of certain sponges.^[41] Molecular studies place animals in a supergroup called the opisthokonts, which also include the choanoflagellates, fungi and a few small parasitic protists.^[42] 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.^[43]
The first fossils that might represent animals appear in the Trezona Formation at Trezona Bore, West Central Flinders, South Australia.^[44] These fossils are interpreted as being early sponges. They were found in 665-million-year-old rock.^[44]
The next oldest possible animal fossils are found towards the end of the Precambrian, around 610 million years ago, and are known as the Ediacaran or Vendian biota.^[45] 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.^[46]
Aside from them, most known animal phyla make a more or less simultaneous appearance during the Cambrian period, about 542 million years ago.^[47] 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.
Some paleontologists suggest that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago.^[48] Trace fossils such as tracks and burrows found in the Tonian era indicate the presence of triploblastic worms, like metazoans, roughly as large (about 5 mm wide) and complex as earthworms.^[49] During the beginning of the Tonian period around 1 billion years ago, there was a decrease in Stromatolite diversity, which may indicate the appearance of grazing animals, since Stromatolites diversity increased when grazing animals went extinct at the End Permian and End Ordovician extinction events, and decreased shortly after the grazer populations recovered. However the discovery that tracks very similar to these early trace fossils are produced today by the giant single-celled protist Gromia sphaerica casts doubt on their interpretation as evidence of early animal evolution.^[50][51]

Groups of animals

Porifera, Radiata and basal Bilateria

he sponges (Porifera) were long thought to have diverged from other animals early.^[52] They lack the complex organization found in most other phyla.^[53] Their cells are differentiated, but in most cases not organized into distinct tissues.^[54] Sponges typically feed by drawing in water through pores.^[55] Archaeocyatha, which have fused skeletons, may represent sponges or a separate phylum.^[56] However, a phylogenomic study in 2008 of 150 genes in 29 animals across 21 phyla 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.^[57] 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.^[58] Both have distinct tissues, but they are not organized into organs.^[59] 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.^[60] 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 the protostomes, the latter of 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 Medusozoa as well.

Deuterostomes

Superb Fairy-wren, Malurus cyaneus

Deuterostomes 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.

Ecdysozoa

Yellow-winged darter, Sympetrum flaveolum

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, perhaps 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.

Platyzoa

Pseudobiceros bedfordi, (Bedford's flatworm)

The Platyzoa include the phylum Platyhelminthes, the flatworms. These were originally considered some of the most primitive Bilateria, but it now appears they developed from more complex ancestors.^[61] A number of parasites are included in this group, such as the flukes and tapeworms. Flatworms are acoelomates, lacking a body cavity, as are their closest relatives, the microscopic Gastrotricha.^[62]
The other platyzoan phyla are mostly microscopic and pseudocoelomate. The most prominent are the Rotifera or rotifers, which are common in aqueous environments. They also include the Acanthocephala or spiny-headed worms, the Gnathostomulida, Micrognathozoa, and possibly the Cycliophora.^[63] These groups share the presence of complex jaws, from which they are called the Gnathifera.

Lophotrochozoa

Roman snail, Helix pomatia

The Lophotrochozoa include two of the most successful animal phyla, the Mollusca and Annelida.^[64][65] The former, which is the second-largest animal phylum by number of described species, 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 because they are both segmented.^[66] Now, this is generally considered convergent evolution, owing to many morphological and genetic differences between the two phyla.^[67]
The Lophotrochozoa also include the Nemertea or ribbon worms, the Sipuncula, and several phyla that have a ring of ciliated tentacles around the mouth, called a lophophore.^[68] These were traditionally grouped together as the lophophorates.^[69] but it now appears that the lophophorate group may be paraphyletic,^[70] with some closer to the nemerteans and some to the molluscs and annelids.^[71][72] 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.^[73]

Model organisms

 

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 life-forms to be genetically sequenced. This was facilitated by the severely reduced state of their genomes, but as 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.^[74]
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.^[75]
Other model organisms belonging to the animal kingdom include the mouse (Mus musculus) and zebrafish (Danio rerio).

History of classification

Aristotle 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, Reptila, Aves, and Mammalia. Since then the last five 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.