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marine mammal information
    classification
    pinnipeds
        harbor seals
        northern elephant seals
        california sea lions
        steller sea lions
        northern fur seals
        guadalupe fur seals
    sea otters
    cetaceans
        toothed whales
        dolphins and porpoises
        baleen whales
    manatees
    polar bears
    endangered

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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 five families 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 aquariums. Their swimming power comes from their large front flippers. In California, this family includes California sea lions, Steller sea lions, northern fur seals, and Guadalupe fur seals.

2. Family Phocidae: True seals have no external ears 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: Walruses are distinctive for their two long tusks. Walruses inhabit the Arctic seas and ice floes. They have no external ears, but can rotate their hind flippers 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 the pharynx (in the neck). These pouches can be inflated to hold the head above water when sleeping, or used as resonance chambers to enhance underwater sound.

B. Suborder Fissipedia includes all other marine mammals in the Order Carnivora except pinnipeds. This suborder is no longer formally recognized, but the adjective "fissiped", meaning paw or pad-footed, is still used to describe these animals.

1. Family Mustelidea: Sea otters are the only marine member of the mustelid family, which includes such land mammals as river otters, weasels and badgers. Sea otters are the smallest marine mammals. They 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 distinguished from other marine mammals. Sea otters are found off the Central Coast of California, and in Washington, Alaska, and Russia.

2. Family Ursidae: Polar bears 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 are completely aquatic, they cannot live on land. They have two front flippers, and their tails are uniquely shaped into two horizontal extensions, called flukes, which provide tremendous swimming power. There are two suborders of cetaceans:

A. Suborder Odontoceti: Toothed whales include dolphins, porpoises, and whales, such as the sperm, orca/killer, narwhal, beluga and beaked whales. Toothed whales have varying numbers of teeth, or may have no functional teeth at all, and breathe through a single blowhole.

B. Suborder Mysticeti: Baleen whales include blue, gray, humpback, and bowhead whales, to name a few. Instead of teeth, baleen whales have rows of strong, closely spaced baleen plates along either side of their upper jaws. These plates filter out and trap small fish and floating plankton, which the whale then swallows. Baleen whales breathe though a pair of blowholes.

III. Order Sirenia: Dugongs and manatees live in warm or tropical waters and feed on plants. In the U.S., 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 27 years of its discovery.

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