Turtles are reptiles of the Order Testudines (all living turtles belong to the crown group Chelonia), most of whose body is shielded by a special bony or cartilaginous shell developed from their ribs. The Order Testudines includes both extant (living) and extinct species. The earliest known turtles date from 215 million years ago,^[1] making turtles one of the oldest reptile groups and a more ancient group than lizards and snakes. About 300 species are alive today, and some are highly endangered.

Turtles cannot breathe in water, but they can hold their breath for various periods of time.

Like other reptiles, turtles are poikilothermic (or "of varying temperature"^[2]). Like other amniotes (reptiles, dinosaurs, birds, and mammals), they breathe air and do not lay eggs underwater, although many species live in or around water. The largest turtles are aquatic.

he largest chelonian is the great leatherback sea turtle, which reaches a shell length of 200 cm (80 inches) and can reach a weight of over 900 kg (2,000 lb, or 1 short ton). Freshwater turtles are generally smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few individuals have been reported up to 200 cm or 80 in (Das, 1991). This dwarfs even the better-known Alligator Snapping Turtle, the largest chelonian in North America, which attains a shell length of up to 80 cm (31½ in) and a weight of about 60 kg (170 lb).

Giant tortoises of the genera Geochelone, Meiolania, and others were relatively widely distributed around the world into prehistoric times, and are known to have existed in North and South America, Australia, and Africa. They became extinct at the same time as the appearance of man, and it is assumed that humans hunted them for food. The only surviving giant tortoises are on the Seychelles and Galápagos Islands and can grow to over 130 cm (50 in) in length, and weigh about 300 kg (670 lb).^[3]

The largest ever chelonian was Archelon ischyros, a Late Cretaceous sea turtle known to have been up to 4.6 m (15 ft) long.^[4]

The smallest turtle is the Speckled Padloper Tortoise of South Africa. It measures no more than 8 cm (3 in) in length and weighs about 140 g (5 oz). Two other species of small turtles are the American mud turtles and musk turtles that live in an area that ranges from Canada to South America. The shell length of many species in this group is less than 13 cm (5 in) in length.

rabbit

Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are seven different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), Cottontail rabbit (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagus furnessi, endangered species on Amami Ōshima, Japan). There are many other species of rabbit, and these, along with pikas and hares, make up the order Lagomorpha.
Rabbits are ground dwellers that live in environments ranging from desert to tropical forest and wetland. Their natural geographic range encompasses the middle latitudes of the Western Hemisphere. In the Eastern Hemisphere rabbits are found in Europe, portions of Central and Southern Africa, the Indian subcontinent, Sumatra, and Japan. The European rabbit (Oryctolagus cuniculus) has been introduced to many locations around the world, and all breeds of domestic rabbit originate from the European. ^[1]

The long ears of rabbits are most likely an adaptation for detecting predators. In addition to their prominent ears, which can measure more than 10 cm (4 in) long, rabbits have long, powerful hind legs and a short tail. Each foot has five digits (one reduced); rabbits move about on the tips of the digits in a fashion known as digitigrade locomotion. Full-bodied and egg-shaped, wild rabbits are rather uniform in body proportions and stance. The smallest is the pygmy rabbit (Brachylagus idahoensis), at only 20 cm in length and 0.4 kg (0.9 pound) in weight, while the largest grow to 50 cm and more than 2 kg. The fur is generally long and soft, and its color ranges through shades of brown, gray, and buff. Exceptions are the black Amami rabbit (Pentalagus furnessi) of Japan and two black-striped species from Southeast Asia. The tail is usually a small puff of fur, generally brownish but white on top in the cottontails (genus Sylvilagus) of North and South America.^[1]

This article is about the domestic dog. For other uses, see Dog (disambiguation).

Domestic dog Fossil range: Late Pleistocene – Recent
A Labrador Retriever
Conservation status
Domesticated
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Canidae Genus: Canis Species: C. lupus Subspecies: C. l. familiaris
Trinomial name
Canis lupus familiaris (Linnaeus, 1758)
Synonyms
These are INVALID scientific names for historical interest only: aegyptius (Linnaeus, 1758), alco (C. E. H. Smith, 1839), americanus (Gmelin, 1792), anglicus (Gmelin, 1792), antarcticus (Gmelin, 1792), aprinus (Gmelin, 1792), aquaticus (Linnaeus, 1758), aquatilis (Gmelin, 1792), avicularis (Gmelin, 1792), borealis (C. E. H. Smith, 1839), brevipilis (Gmelin, 1792), cursorius (Gmelin, 1792), domesticus (Linnaeus, 1758), extrarius (Gmelin, 1792), ferus (C. E. H. Smith, 1839), fricator (Gmelin, 1792), fricatrix (Linnaeus, 1758), fuillus (Gmelin, 1792), gallicus (Gmelin, 1792), glaucus (C. E. H. Smith, 1839), graius (Linnaeus, 1758), grajus (Gmelin, 1792), hagenbecki (Krumbiegel, 1950), haitensis (C. E. H. Smith, 1839), hibernicus (Gmelin, 1792), hirsutus (Gmelin, 1792), hybridus (Gmelin, 1792), islandicus (Gmelin, 1792), italicus (Gmelin, 1792), laniarius (Gmelin, 1792), leoninus (Gmelin, 1792), leporarius (C. E. H. Smith, 1839), major (Gmelin, 1792),mastinus (Linnaeus, 1758), melitacus (Gmelin, 1792), melitaeus (Linnaeus, 1758), minor (Gmelin, 1792), molossus (Gmelin, 1792), mustelinus (Linnaeus, 1758), obesus (Gmelin, 1792), orientalis (Gmelin, 1792), pacificus (C. E. H. Smith, 1839), plancus (Gmelin, 1792), pomeranus (Gmelin, 1792), sagaces (C. E. H. Smith, 1839), sanguinarius (C. E. H. Smith, 1839), sagax (Linnaeus, 1758), scoticus (Gmelin, 1792), sibiricus (Gmelin, 1792), suillus( C. E. H. Smith, 1839), terraenovae (C. E. H. Smith, 1839), terrarius (C. E. H. Smith, 1839), turcicus (Gmelin, 1792), urcani (C. E. H. Smith, 1839), variegatus (Gmelin, 1792), venaticus Gmelin, 1792), vertegus (Gmelin, 1792)[1]

The dog (Canis lupus familiaris)^[2] is a domesticated subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet varieties and is also sometimes used to describe wild canids of other subspecies or species. The domestic dog has been one of the most widely kept working and companion animals in human history, as well as being a food source in some cultures. There are estimated to be 400 million dogs in the world.^[3]

The dog has developed into hundreds of varied breeds. Height measured to the withers ranges from a few inches in the Chihuahua to a few feet in the Irish Wolfhound; color varies from white through grays (usually called blue) to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; and, coats can be very short to many centimeters long, from coarse hair to something akin to wool, straight or curly, or smooth.^[4]

cat

The cat (Felis catus), also known as the domestic cat or house cat to distinguish it from other felines, is a small predatory carnivorous species of crepuscular mammal that is valued by humans for its companionship and its ability to hunt vermin, snakes and scorpions. It has been associated with humans for at least 9,500 years.^[4]

A skilled predator, the cat is known to hunt over 1,000 species for food. It can be trained to obey simple commands. Individual cats have also been known to learn on their own to manipulate simple mechanisms, such as doorknobs. Cats use a variety of vocalizations and types of body language for communication, including meowing, purring, hissing, growling, squeaking, chirping, clicking, and grunting.^[5] With 69 million of them present in American homes,^[6] cats are the most or the second most popular pets in that country. Cats also may be the most popular pet in the world, with over 600 million in homes all over the world.^[7] They are also bred and shown as registered pedigree pets. This hobby is known as the "Cat Fancy".

Until recently the cat was commonly believed to have been domesticated in ancient Egypt, where it was a cult animal.^[8] However a 2007 study found that all house cats are probably descended from a group of as few as five self-domesticating African Wildcats Felis silvestris lybica circa 8000 BC, in the Near East.^[3]

The horse (Equus caballus) is a odd-toed ungulate mammal, one of eight living species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4500 BC, with domestication of the horse believed to have been widespread by 3000 BC. By 2000 BC the use of domesticated horses had spread throughout the Eurasian continent. While most horses today are domesticated and live in close proximity to humans, there are still endangered populations of the Przewalski's horse, the only remaining true wild horse that has no domesticated ancestors, as well as more common feral horses, such as the American Mustang, which live in the wild but are descended from domesticated ancestors.

Horses are described with a large number of specific terms that describe everything from their anatomy to their life stages, colors, white markings, breeds, locomotion and behavior. They have a wide range of sizes, and are anatomically designed as a herbivore with the ability to use speed to escape predators. Horses have a well-developed sense of balance and a strong fight-or-flight instinct. Related to this need to flee from predators in the wild is a unique trait: horses are able to sleep both standing up and laying down. Female horses, called mares, carry their young for approximately 11 months and a young horse, called a foal, can stand and run shortly following birth. Most horses begin training under saddle or in harness between the ages of two and four, reaching full adult development by age five, and have an average lifespan of between 25 and 30 years.

Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance; "cold bloods," such as draft horses and some ponies, suitable for slow, heavy work; and "warmbloods," developed from crosses between hot bloods and cold bloods, often creating specially-developed breeds, particularly in Europe. There are over 300 breeds of horses in the world today, developed for many different uses. Some regions in the world are known for a specialty in development of a particular breed or set of breeds, such as harness horses in Russia or draft and pony breeds in Great Britain.

Horses and humans have extensive interactions today, not only in a wide variety of sports competitions and non-competitive recreational pursuits, but also working activities such as police, draft work, entertainment, assisted learning and therapy, and modern warfare. Many products are also made from horse meat, milk, hide, hair and bone, as well as pharmaceuticals made from the urine of pregnant mares.

Domesticated horses require specialized care to stay healthy, including proper provision of food, water and shelter, but also additional care from specialists such as veterinarians and horseshoers, or farriers. There is a wide variety of riding and driving techniques for managing horses, using many different styles of equipment and methods of control.

A monkey is any member of either the New World monkeys or Old World monkeys, two of the three groupings of simian primates, the third group being the apes. There are 264 known extant species of monkey.

The New World monkeys are classified within the parvorder Platyrrhini, whereas the Old World monkeys (superfamily Cercopithecoidea) form part of the parvorder Catarrhini, which also includes the apes. Thus, scientifically speaking, monkeys are paraphyletic (not a single coherent group), and Old World monkeys are actually more closely related to the apes than they are to the New World monkeys.

Because of their similarity to monkeys, apes such as chimpanzees and gibbons are often called "monkeys" in informal usage, though they are not monkeys. Conversely, due to its size (up to 1 m/3 ft) the Mandrill is often thought to be an ape, but it is actually an Old World monkey. Also, a few monkey species have the word "ape" in their common name.

Monkeys range in size from the Pygmy Marmoset, at 140 to 160 millimetres (5-6 in) long (plus tail) and 120 to 140 grams (4-5 oz) in weight, to the male Mandrill, almost 1 metre (3.3 ft) long and weighing 35 kilograms (77 lb). Some are arboreal (living in trees) while others live on the savannah; diets differ among the various species but may contain any of the following: fruit, leaves, seeds, nuts, flowers, eggs and small animals (including insects and spiders).

Some characteristics are shared among the groups; most New World monkeys have prehensile tails while Old World monkeys have non-prehensile tails or no visible tail at all. Some have trichromatic colour vision like that of humans, others are dichromats or monochromats. Although both the New and Old World monkeys, like the apes, have forward facing eyes, the faces of Old World and New World monkeys look very different, though again, each group shares some features such as the types of noses, cheeks and rumps.

A snake is an elongate reptile of the suborder Serpentes. Like all reptiles, snakes are covered in scales. All snakes are carnivorous and can be distinguished from legless lizards by their lack of eyelids, limbs, external ears, and vestiges of forelimbs. The 2,700+ species of snakes spread across every continent except Antarctica ranging in size from the tiny, 10 cm long thread snake to pythons and anacondas at 9 m (30 ft) long. In order to accommodate snakes' narrow bodies, paired organs (such as kidneys) appear one in front of the other instead of side by side.

While venomous snakes comprise a minority of the species, some possess potent venom capable of causing painful injury or death to humans. However, venom in snakes is primarily for killing and subduing prey rather than for self-defense. Snakes may have evolved from a lizard which adapted to burrowing during the Cretaceous period (c 150 Ma), though some scientists have postulated an aquatic origin. The diversity of modern snakes appeared during the Paleocene period (c 66 to 56 Ma).

Snake eating a rodent

Snake eating a lizard near Ibor river (Extremadura, Spain)

All snakes are strictly carnivorous, eating small animals including lizards, other snakes, small mammals, birds, eggs, fish, snails or insects.^[2][3][4] Because snakes cannot bite or tear their food to pieces, a snake must swallow its prey whole. The body size of a snake has a major influence on its eating habits. Smaller snakes eat smaller prey. Juvenile pythons might start out feeding on lizards or mice and graduate to small deer or antelope as an adult, for example.

The snake's jaw is the most unique jaw in the animal kingdom. Contrary to the popular belief that snakes can dislocate their jaws, snakes have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull (see snake skull), allowing them to open their mouths wide enough to swallow their prey whole, even if it is larger in diameter than the snake itself,^[3] as snakes do not chew. For example, the African Egg-eating Snake has flexible jaws adapted for eating eggs much larger than the diameter of its head.^[4] This snake has no teeth, but does have bony protrusions on the inside edge of its spine which are used to aid in breaking the shells of the eggs it eats.^[4]

While the majority of snakes eat a variety of prey animals, there is some specialization by some species. King cobras and the Australian Bandy-bandy consume other snakes. Pareas iwesakii and other snail-eating Colubrids of subfamily Pareatinae have more teeth on the right side of their mouths than on the left, as the shells of their prey usually spiral clockwise^[5][6]

Some snakes have a venomous bite, which they use to kill their prey before eating it.^[7][3] Other snakes kill their prey by constriction.^[3] Still others swallow their prey whole and alive.^[3][4]

African Egg-eating snake

After eating, snakes become dormant while the process of digestion takes place.^[8] Digestion is an intense activity, especially after consumption of very large prey. In species that feed only sporadically, the entire intestine enters a reduced state between meals to conserve energy, and the digestive system is 'up-regulated' to full capacity within 48 hours of prey consumption. Being cold-blooded (ectothermic), the surrounding temperature plays a large role in a snake's digestion. 30 degrees Celsius is the ideal temperature for snakes to digest their food. So much metabolic energy is involved in a snake's digestion that in Crotalus durissus, the Mexican rattlesnake, an increase of body temperature to as much as 1.2 degrees Celsius above the surrounding environment has been observed.^[9] Because of this, a snake disturbed after having eaten recently will often regurgitate its prey in order to be able to escape the perceived threat. When undisturbed, the digestive process is highly efficient, with the snake's digestive enzymes dissolving and absorbing everything but the prey's hair and claws, which are excreted along with waste.