The diverse order Carnivora includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" (often popularly applied to members of this group) can refer to any meat-eating animal. Carnivorans are the most diverse in size of any mammalian order, ranging from the Least Weasel (Mustela nivalis), at as little as 25 grams (0.88 oz) and 11 centimetres (4.3 in), to the Polar Bear (Ursus maritimus) which can weigh up to 1,000 kilograms (2,200 lb), to the Southern Elephant Seal (Mirounga leonina) whose adult males weigh up to 5,000 kilograms (11,000 lb) and measure up to 6.9 metres (23 ft) in length.
The first carnivoran was a carnivore, and nearly all carnivorans today primarily eat meat. Some, such as cats, pinnipeds, and weasels, are obligate carnivores. Others, such as bears, are more omnivorous depending on the local habitat; the Giant Panda is almost exclusively an herbivore but will take fish, eggs and insects, while the Polar Bear's harsh habitat forces it to mainly subsist on prey. Carnivorans have teeth, claws, and binocular vision adapted for catching and eating other animals. Many hunt in packs and are social animals, giving them an advantage over larger prey.
The different groups of canivores are as follows: