Even-toed ungulates | Artiodactyla

Families in this order

• Cetaceans | CetaceaMarine mammals that left the land some fifty million years ago and adapted fully to life in water. Genetically the most deeply nested branch within the even-toed ungulates: their closest living relative is not another whale, but the hippopotamus. Long treated as a separate order (Cetacea); this guide follows the classification of the Mammal Diversity Database, which places them among the even-toed ungulates.
• Rorquals | Balaenopteridae3 speciesBaleen whales with a long, streamlined body, a small dorsal fin set far back and throat grooves: pleats in the skin of throat and chest that let the mouth cavity expand greatly when feeding. Instead of teeth, baleen plates of horn-like material hang from the upper jaw, with which the animal strains krill and small schooling fish from the water it has gulped. They have two blowholes. Like all whales they belong to the even-toed ungulates; the hippopotamus is their closest living relative on land.
• Oceanic dolphins | Delphinidae7 speciesThe most species-rich family of toothed whales, comprising the dolphins, the pilot whales and the Killer Whale. Most species have a beak, conical teeth and a sickle-shaped dorsal fin in the middle of the back; the forehead holds the melon, a fat-filled organ that focuses the clicks with which they orientate and locate prey. They have a single blowhole. They are social animals living in groups of a few to thousands. Like all whales they belong to the even-toed ungulates; the hippopotamus is their closest living relative on land.
• Porpoises | Phocoenidae1 speciesSmall toothed whales without a beak, with spade-shaped teeth instead of the conical teeth of dolphins and usually a low, triangular dorsal fin. They live alone or in small groups and are inconspicuous at the surface. One species lives in Europe, the Harbour Porpoise.
• Sperm whales | Physeteridae1 speciesA single living species, the Sperm Whale: the largest toothed whale, with a block-shaped head taking up about a third of the body length and containing an organ filled with waxy oil, the spermaceti organ. Teeth are found only in the narrow lower jaw. The single blowhole lies at the front left of the head, so that the blow is directed forwards at an angle.
• Bovids | Bovidae19 speciesThe horns are permanent: a bony core growing out of the frontal bone and covered for life by a sheath of horn that grows on from the base and is never shed. They therefore lengthen year by year and in many species carry rings marking the successive seasons; in part of the family the females carry them too. Every species chews the cud, and the upper jaw has no incisors: grass is cut between the lower incisors and a hard horny pad and later ground down by crescent-ridged cheekteeth. The hoof is a hard outer rim around a softer, springy sole — the climbing kit of the European representatives, nearly all of which are animals of mountain and rock: ibex, chamois and wild sheep on steep ground, and along the southern edge the gazelles and oryxes of steppe and desert. The wisent is the continent's only wild cattle, brought back from captive stock. One well-developed young is born.
• Deer | Cervidae11 speciesAn antler is not horn but bone, and it is made anew each year. It grows from a permanent stump on the forehead, under a skin of finely haired velvet that supplies it with blood; when growth is complete the blood supply is cut off, the velvet dies and is rubbed away against bushes, after which the dead bone is carried through the rut and afterwards shed. The growth costs a great deal of calcium and follows the length of the day. Only the males carry antlers, the reindeer excepted; in one species now established in Europe antlers are absent altogether and the males carry long projecting canines instead. Beyond that they are ruminants without upper incisors, with long legs and a springing, bounding gait, and with scent glands in front of the eyes, on the legs and between the hooves. In most species the rut goes with calling, thrashing and fighting. The calf is spotted and lies motionless in cover for its first weeks.
• Pigs | Suidae1 speciesThe only even-toed ungulate in Europe that does not chew the cud: the stomach has a single chamber and the menu is an omnivore's — roots, tubers, fungi, acorns and beech mast, earthworms, small animals and carrion. That food is found by smell and dug out with the snout, which ends in a round cartilaginous disc supported by a bone of its own and driven through the ground like a plough by heavy neck muscles. The canines grow throughout life and curve outwards as tusks, the lower being constantly whetted against the upper and so kept sharp. Each foot carries four toes, the outer two of which bear on soft ground. The coat is of stiff bristles with a mane over the neck. The piglets are striped lengthwise and are born in a nest of dragged-together plant material; the litter is large — exceptional for an ungulate.