|The Robinson Library >> Class Chondrichthyes|
The whale shark is the largest fish in the sea, being 18-40 feet long and weighing an average of 20.6 tons; females are larger than males.
In addition to size, the whale shark is distinguished by its blunt snout and a mouth up to 4 feet wide at the very front of the head; most other sharks have a more pointed snout and the mouth is on the underside of the head. The back and sides are gray to brown in color, with characteristic white spots among pale vertical and horizontal stripes;the belly is white. Whale sharks have two dorsal finds set rearward on the body, with the first one always much larger than the second, and a dual-lobed tail.
Distribution and Habitat
Whale sharks are found in all tropical and warm temperate seas, except the Mediterranean. Although they are most common offshore, individuals have been known to come close to shore and have even entered lagoons and coral atolls. They spend most of their time near the surface. Although whale sharks do appear to move with the seasons, it is more likely they are following food sources than that they are migrating.
Whale sharks are filter feeders, meaning they take in a quantity of water, force that water through two sets of 5 very large gills (one set per size), and then swallow whatever is left behind. Plankton makes up the largest part of their diet, but krill, small fish, squid, and even small crustaceans are also taken. Unlike other filter feeders that take in water passively while swimming, whale sharks actually suck the water in, indicating they possess sensory organs that "tell" them when a large supply of food is in range.
The courtship and breeding behavior of whale sharks has never been observed. It is known that they give birth to live young, but only because one pregnant female was found with hundreds of embryonic pups in her uterus; a whale shark birth has never been observed.
It is believed that whale sharks live 100-150 years or more.
Little else is known about whale sharks except that they are never seen in groups, that they rarely swim faster than about 3 mph, and that they swim by moving the entire body side to side (other sharks swim by moving just the tail).
Whale sharks are listed as threatened.
|The Robinson Library
>> Class Chondrichthyes
This page was last updated on September 01, 2018.