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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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Marine
Mammal Classification