A
shark is a predatory cartilaginous
fish.
Sharks are found in all types of
seas, but
typically prefer warm
water. About 250 different species of
sharks exist, ranging from
the 2-ft pygamy
shark to the 50-ft whale
shark.
Sharks have pointed noses and
crescent-shaped
mouths with several rows of triangular
teeth.
Sharks are
warm-blooded animals, which means that their body temperature is higher than that of
the
water.
Actually, last week, in my college
biology class, we watched a
documentary all about
Great White Sharks. If you study these
sharks, you will find
that they hunt in specific ways for their
prey. They prefer a single target, which poses
less of a threat. The
shark cruises along the bottom, scanning the surface for the
silhouettes of
prey, such as
sealions,
dolphins, or
seals. Their dark coloring on
their dorsal side enables them to be unseen from the surface. The ventral
white
coloring prevents lower
animals from seeing them above. Once a target is spotted, the
shark picks up speed and crashes into the
animal with a surprise
attack. Normally,
this huge blow either
kills the target, or stuns them, allowing the
shark to deliver
another blow. The
sharks backs off, waits for the
animal to die, and then moves in for
dinner. A
shark uses its
tail to assist it in sawing off pieces of
food. They clamp on
to the dead
animal with their
teeth, and then violently move their
tail back and forth,
sinking their
teeth in farther, and ripping off a bite. On average, one shark makes about three kills a year, depending on the size of the targets.
Individual
sharks compete for access to prey.
Dominance is related to their size, with the larger
sharks being more dominant, and also feeding first. They express
dominance by
body language. Characteristic postures are used to signal their intentions.