The feeding habits of sharks are
varied and are based on the four main diet types: fish, mammals, crustaceans and
diet of a shark determines many aspects of its life including where it
lives, the time of day that it is active, the depths at which it can be found, and the type of teeth and jaw that it possesses.
| Sharks that eat fish are usually pelagic,
ranging throughout the water column. Examples in Canadian waters include
porbeagle, mako and blue sharks. Their teeth tend to be narrow and
sharp in order to grasp their prey while swimming. This picture shows the stomach contents of a
fish-eating porbeagle shark. Visible in the photo are the partially
digested remains of lancetfish, squid and haddock.
Sharks like the great white feed mainly upon
marine mammals like seals or sea lions. Although their diets are not
exclusive to mammals they possess teeth that are specialized for handling large
animals like cetaceans. The teeth are serrated and allow them to remove large
pieces of flesh.
Bottom dwelling species of shark like the deepsea cat shark eat crabs and other
crustaceans with a hard outer shell. Sharks that eat crustaceans
have short grinding teeth that are used to crush their food. Relatively
few of the shark species in Canada are this type of feeder.
Sharks that eat plankton have
specialized feeding mechanisms. The basking shark eats plankton by
swimming at the surface with its mouth open. The water rushes
through the mouth and out the gills. Gill rakers at the entrance to the
gill catch and filter out all of the plankton (small
organisms that float in the water).
| Gill rakers, like the ones seen in this
picture, are numerous in the basking shark, but are shed in the winter when
the food supply of plankton is scarce.
modified from Sharks. Joyce Pope. 1997. Firefly Pocket Guide
Series. Firefly Books Ltd. Willowdale, Ontario.
modified from Sharks. Miranda Macquitty. 1992. Eyewitness Books Series.
Stoddart Publishing Co. Ltd. Toronto, Ontario.
||Plankton, are the microscopic organisms that
float in the water. They are often clear or translucent like the
ones seen in this photo. It takes large amounts of these small
organisms to support a shark as large as a basking shark.