Whale shark

A WWF-supported ecotourism project centred around swimming with whale sharks (while following ... rel=
A WWF-supported ecotourism project centred around swimming with whale sharks (while following strict rules so as not to disturb the animals) has brought a flourishing tourism industry to Donsol, the Philippines.
© WWF-Canon / Jürgen FREUND

The largest fish in the world

What
The sole living member of its family, the whale shark is by far the world's largest living fish. It is the biggest shark and is not a whale. Whale sharks are found in tropical and temperate waters worldwide.

Whale sharks have internal fertilisation and produce live young. The whale shark has the biggest mouth among sharks.

About
Its massive, fusiform body reaches lengths in excess of 14 m and weighs up to 12 tonnes. It has a huge mouth which can be up to 1.4 m wide. Its mouth is at the very front of its head (not on the underside of the head like in most sharks). It has a wide, flat head, a rounded snout and small eyes. The whale shark has distinctive light-yellow markings (random stripes and dots) on its very thick dark gray skin.

This enormous shark is a filter feeder and sieves enormous amounts of plankton to eat through its gills as it swims. The prey includes plankton, krill, small fish, and squid. The shark can process over 6000 liters of water each hour.

Why
Whale sharks are regarded as highly migratory - although these 'migration patterns' are poorly understood. They are generally solitary creatures. They are slow swimmers at speeds of no more than 5 kmph. They swim by moving the end of their bodies from side to side (not just their tails, like the great white and certain other sharks). Whale sharks are not aggressive toward people and usually indifferent to divers, but an accidental blow from the powerful tail has caused serious injury.

Although they have approximately 3,000 tiny teeth (each less than 6 mm in length), these teeth are not used while feeding. Instead, the whale shark can sieve prey items as small as 1 mm through the fine mesh of the gill-rakers. They are able to open their mouth to a great width (greater than 1 m) to optimise feeding.

Your chances of seeing one in the wild
This species is rare. Prior to the mid-1980s, there had been less than 350 confirmed reports of whale sharks worldwide. Australia is one of the most reliable locations to find whale sharks. Regular sightings have also been recorded from many other regions including India, the Maldives, South Africa, Belize, Mexico, the Galapagos Islands, Southeast Asia and Indonesia.

The Whale Shark is listed as 'vulnerable and migratory' under the Environment Protection and Biodiversity Conservation Act 1999. They are listed as 'vulnerable' by IUCN.

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