Marine MammalsRead more about Whales
Read more about Seals and Sea Lions
MAMMALS are a special group of vertebrates, with a combination of characteristics that separate them from all other animals: Mammals breathe air through lungs, bear live young, produce milk for their young, are warm-blooded, and have hair or fur. Mammals are often distinguished by their relatively large brains and their variety of tooth sizes and shapes.
MARINE MAMMALS are mammals that have adapted, or adjusted, to life in the ocean. Marine mammals have all the characteristics of mammals, yet they are distinctive in their appearance and survival strategies. Learning to identify marine mammals is made easier by learning their scientific classification.
I. Order: CARNIVORA includes three groups of marine mammals:
A. Suborder: PINNIPEDIA are ''flipper-footed" marine mammals. Pinnipeds can safely come out on land to rest, breed and give birth, and are comprised of three families:
1. Family: OTARIIDAE
(Sea Lions and Fur Seals) have visible external ears, and can "walk'' on all four flippers by rotating their rear flippers forward. They are more mobile on land than true seals, and are often seen in circuses and oceanaria. Their swimming power comes from their large front flippers. In California, this family includes California sea lions, northern fur seals, and Guadalupe fur seals.
2. Family PHOCIDAE
(True seals) have no external ear, and crawl on land because their front flippers are small and their hind flippers cannot rotate forward. Their swimming power comes from their large, almost fan-like rear flippers. In California this family includes harbor seals and northern elephant seals.
3. Family ODOBENIDAE
(Walrus) are distinctive for their two long tusks, walruses inhabit the Arctic seas and ice floes. They have no external ear, but can rotate their hind flippers forward and "walk'' on land. They are set apart from other pinnipeds not only by their tusks, but also by the presence of two large air pouches, or sacs, extending from each side of the pharynx. These pouches can be inflated to hold the head above water when sleeping, or used as resonance chambers to enhance underwater sounds.
Sea Otters (Enhydra lutra) are the only marine representative of the mustelid family, which includes such land mammals as weasels and skunks. Sea otters are the smallest marine mammals and do not inhabit the open ocean. Instead, they live among coastal kelp beds, where they dive and hunt for a variety of shellfish and marine invertebrates. With their exceptionally thick dark fur, longer tail, lack of true flippers, and their ability to use a rock as a feeding tool, sea otters are distinguish from other marine mammals. Sea otters are found off the Central Coast of California, Washington, Alaska, and Russia.
POLAR BEARS (Ursus maritimus) are designated as marine mammals because they depend on the ocean for a majority of their food. Thus, they are protected under marine mammal protection laws. Polar bears range throughout the Arctic regions, including parts of Alaska.
II. Order CETACEA
(WHALES, DOLPHINS, and PORPOISES) have two front flippers and their tails are uniquely shaped into horizontal extensions, called flukes, which provide tremendous swimming power. There are two suborders of cetaceans:
A. Suborder ODONTOCETI
(TOOTHED WHALES) includes dolphins, porpoises and whales, such as the sperm whale, orca, narwhal, and beluga whale. These whales have some two to fifty teeth, and breathe through a single blowhole.
B. Suborder MYSTICETI
(BALEEN WHALES) includes blue, gray, humpback, and bowhead whales, to name a few. Instead of teeth, a baleen whale has rows of strong closely spaced baleen plates along either side of the upper jaw. These plates function to filter out and trap small sea life which serve as food. Baleen whales breathe through a pair of blowholes.
III. Order SIRENIA
(Dugongs and Manatees) are found in warm or tropical waters, and feed on algae. Manatees are found in areas of coastal Florida. Another species of sirenian, called the Steller sea cow, once inhabited Arctic waters, but was hunted to extinction by 1768 within 30 years of its discovery.