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Food
All sharks are flesh eaters, feeding on fishes, crustaceans,
mollusks, sea mammals and birds etc. Each species of shark occupies
a specific feeding niche within its habitat. The shape of the sharks
teeth can often give us a hint of that this niche look like. Sharks
with flat, triangular teeth with serrated edges are equipped to rip
chunks of flesh from their prey, while sharks with broad, pavement-like
teeth are more adapted for crushing mollusks and crustaceans. For
instance, hammerheads prefer stingrays and horn sharks prefer sea
urchins. The zebra shark prefers mollusks, crabs, shrimps and small
bony fishes and the basking shark dines on tiny planktons. Even though
many species are selective about their prey and seem to have preferences
it does not mean that they would turn down an easy meal, just because
their teeth "weren't right".
Some sharks are generalist,
eating whatever food is available when they are hungry. If a shark
eat an object that they cannot digest, such as a turtle shell or a
bottle, they can expel it by thrusting their stomach up and out through
their mouth, and then retract it. This behavior is probably very infrequent
and only happens under unusual circumstances.
Sharks are compared
to mammals very economical on energy. It has been estimated that a
30 kg meal of flesh taken by a great white shark will last it for
45 days and a lemon shark will eat 2-5 percent of its body weight
every 40-80 hours. In human terms that is approximately one burger
and fries every two to three days.
Ref: Aitken K (1998), Sharks & rays of
Australia, New Holland Publishers Pty Ltd, Australia -- Springer VG
and Gold JP (1989), Sharks in quetion: the Smithsonian answear book,
Smithsonian Institution Press, Washington, D.C. London
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