The World’s Largest Living Fish is a Shark

The whale shark, locally known as “ butanding “, is the world’s largest fish. This gentle giant is known to grow to great lengths of up to 18 meters and can weigh up to 34 tonnes. As a highly migratory species, whale sharks are distributed worldwide in warm and temperate seas of the Atlantic, Pacific and Indian Oceans. They can migrate long distances through international waters to favored coastal areas in a few months of the year when the plankton they feed on is abundant.

Food is an important factor for the growth, migration and abundance of whale sharks in time and space. Its presence is highly associated with blooms of planktonic organism and changes in water temperature. Unlike other species of sharks, the whale shark can neither bite nor chew. Its thousand of teeth are so tiny that it can only eat small shrimps, fish and plankton by using its modified gift rakers as suction filter.

Whale sharks are slow growing, maturing sexually only after so many years and with long interval between pregnancies. Female have been found to produce as many as 300 embryos in her uterus, although it is thought that less than 10% of the young survive to adulthood. Upon giving birth, the mother sharks leave her young to fend for themselves. In effect, the species have low reproductive potential and low capacity for population increase. These make the species highly vulnerable to exploitation.

The ecological role of whale sharks is not yet fully understood but the links of these giants with other processes within an ecosystem cannot be underestimated. Whale sharks are related to important ecological processes such as crab, fish and coral spawning. As possible indicators of plankton-rich patches, whale sharks may be using baitfish to locate their prey.