Marine mammals are a group of roughly 120 species of ocean-dwelling mammals or depend on the ocean for food. Marine mammals evolved from land dwelling ancestors, but not all from the same ancestor, Cetaceans and Sirenians are thought to descendant from an ungulate ancestor, while the otter, pinnipeds and polar bear are descended from a caniform ancestor. They have adapted to the life in the sea and share some characteristics, like a generally large size, hydrodynamic body shapes, appendages and several adaptations for controlling warmth. Many populations of mammals living in the water are vulnerable or endangered throughout a history of commercial exploitation for blubber, meat, ivory and fur.
Mammals living in the water breathe air, while for example fish extract oxygen from the water through their gills. Did you know polar bears can swim 74 kilometers in a day?
Image of the ocean by Dirk Ingo Franke, licensed under CC-BY-SA
Carnivores
Polar bear
Dolphins, porpoises, and whales
Gray's beaked whale
Benguela dolphin
Hector's beaked whale
Hector's dolphin
Layard's beaked whale
Beluga
True's beaked whale
Atlantic dolphin
Lesser beaked whale
Devil fish
Bering sea beaked whale
Southern right whale
Narwhal
Pygmy killer whale
Killer whale
Pacific pilot whale
Melon-headed whale
Long-finned pilot whale
Common porpoise
Cochito
Grey dolphin
Black porpoise
Bottlehead
Dall's porpoise
Flatheaded bottlenose whale
Franciscana
Pygmy sperm whale
False killer whale
Chinese white dolphin
Fraser's dolphin
Bridled dolphin
Atlantic white-sided dolphin
Atlantic spinner dolphin
White-beaked dolphin
Euphrosyne dolphin
Blackchin dolphin
Atlantic spotted dolphin
Hourglass dolphin
Long-beaked dolphin
Pacific white-sided dolphin
Bowhead whale
Rough-toothed dolphin
Dusky dolphin
Common minke whale
Shepherd's beaked whale
Northern right whale dolphin
Coalfish whale
Southern right whale dolphin
Bryde's whale
Blue whale
Bottle-nosed dolphin
Bunch
Common rorqual
North atlantic beaked whale
Andrews' beaked whale
Arnoux's beaked whale
Cuvier's beaked whale
Arch-beaked whale
Baird's beaked whale
Indo-pacific beaked whale
Blainville's beaked whale
Pygmy right whale
Gervais' beaked whale
Commerson's dolphin
North atlantic right whale
Ginkgo-toothed beaked whale
Black dolphin
Dugongs, manatees, and sea cows
American manatee
African manatee
Read more at the list of biomes of the world...