Mammal Characteristics
· warm-blooded
· gives birth to live young
· nurses offsprings with milk
· has body hair
(at some stage in life)
Marine Mammals are composed of animals from four
Orders
Cetacea
Dolphins, Porpoises & WhalesSirenia
Manatees & Dugong Pinnipedia
Seals, Sea Lions & Walrus
Carnivora
Polar Bear, Sea Otter& Marine Otter
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Cetacea is the scientific name for the order of mammals that includes all dolphins, porpoises and whales. All Cetaceans are completely aquatic, carrying out all aspects of their lives in the water. The word Cetacea comes from the Greek word ketos, which means whale. There is one other Order of completely aquatic mammals, Sirenia, which includes only four species, three manatees and the dugong. The Order Pinnipedia, seals, sea lions and the walrus, is the second largest group of marine mammals. Pinnipeds are amphibious and do not spend their entire lives in the water as do the Sirenians and Cetaceans. Pinnipeds must haul out on land, or ice to give birth
and to molt, and for most species, mating also takes place out of the water. The last taxonomic group represented among the marine mammals is the Order Carnivora. It includes the sea otter and marine otter from the
suborder Mustelidae (badgers, otters, minks and ferrets and the polar bear, from the suborder Ursidae (bears). These animals are also amphibious in their life style, although the sea otter gives birth in the water.
Cetaceans - Mysticetes and Odontocetes
The cetaceans are well adapted to living a fully aquatic life. For insulation, they
have a thick layer of blubber which is much more efficient at conserving body heat than wet hair. They have lost almost all the hair
on their bodies. They have also lost their hind limbs and most of their
hip bones. For propulsion, they have horizontal tail fins, or flukes, and
very large muscles in their tail, or peduncle. Their front limbs have been
modified into paddle-like flippers. The Order Cetacea has been
subdivided into two Suborders: the Mysticeti (baleen whales) and the Odontoceti (toothed whales).
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