Seals can be found in all waters of the world, from the Arctic
and Antarctic to tropical waters. They belong to the order Pinnipedia,
which means "fin-footed". Pinnipeds have four flippers - one
pair in front, and one pair in back.
There are 3 different families in the Pinnipeadia group.
Phocidae (true seals), Otaridae (fur seals and sea lions) and
Odobenidae (walrus). Pinnipeds, which arose from land mammals, have
evolved slick bodies, ideal for gliding through water.
Pinnipeds are mammals. They're warm-blooded, give live birth,
nurse their young, breathe air, and have hair. Since they live in the
marine environment and find their food at sea, they are called marine
mammals. Other marine mammals include whales and sea otters.
Eared seals (sea lions and fur seals) have external ear flaps
and are able to use their flippers for walking on land by rotating
their hind flippers forward. While swimming, they use their front
flippers for power.
True seals don't have external ear flaps and can't rotate their
hind flippers. On land, they pull themselves forward by their fore
flippers while their hind flippers are dragged behind them. While
swimming, they use their rear flippers for power.
All seals are carnivores. Their diet consists mostly of fish,
crustaceans and shellfish. Depending on the season or availability,
they will feed on different prey.
Unlike popular belief, seals are not at the top of the marine
food chain. Orcas ("killer" whales) eat seals.
Seals are protected from the cold by a thick layer of blubber
combined with a thick fur coat.
Seals use their coarse, sensitive and continuously growing
whiskers to search for food. The seal sweeps its upper lip to and fro,
using their whiskers to detect fish in murky waters.
Seals have large, round eyes, which are able to focus both above
and below water.
Seals have an excellent sense of smell, allowing them to detect
predators. Females also use their smell to recognize their pups. While
swimming, the nostrils are kept tightly shut.
Seals hear very well both above and below water. Females and
pups often call to each other. Seals also make growls and grunts
underwater, especially during the breeding season.
Seals give birth to one pup at almost exact one-year intervals.
They nurse for a brief (between 4 days and 1 month), but intense
period. Most mother seals don't feed while nursing. After weaning her
pup, she will have to regain her weight and rebuild her blubber
stores. The mother will return to the sea to feed, while her pup is
left to learn to swim and to hunt fish on its own. The pup will make
the transition from dependency to independence guided almost entirely
Male seals generally compete to get access to females. They
usually mate in the few days before the females return to sea after
weaning their pups. The embryo will begin to develop, but then remain
suspended in the womb (this is called delayed implantation), until the
female has rebuilt her blubber stores. Gestation is about 9 months.
Seals are able to hold their breath for a long times during dives,
using oxygen stored in the blood and muscles as well as the lungs.
Seals can sleep underwater. They can even surface to breathe