Dolphins Wallpaper, #10202

Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 metres (4 ft) and 40 kilograms (88 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and ten tonnes (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: Dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.In this article, the second definition is used. Porpoises (suborder Odontoceti, family Phocoenidae) are thus not Dolphins in this sense. Orcas and some closely related species belong to the Delphinidae family and therefore qualify as Dolphins, even though they are called whales in common language. A group of Dolphins can be called a "school" or a "pod". Male Dolphins are called "bulls", females "cows" and young Dolphins are called "calves".Dolphins, along with whales and porpoises, are descendants of terrestrial mammals, most likely of the Artiodactyl order. The ancestors of the modern day Dolphins entered the water roughly fifty million years ago, in the Eocene epoch.