Whale shark

Page - September 21, 2007

whale shark

Estimated population:

Unknown. The whale shark is considered vulnerable by the IUCN.

Ways to identify this species:

Whale sharks are grayish-brown with a white underbelly and white spots and lines. This species is the largest fish in the world measuring 20 - 55 feet in length. Whale sharks are usually seen in the open water.

Biology

  • Believed to have originated 60 million years ago, whale sharks are found in tropical and temperate waters worldwide at depths up to 100 feet.
  • This species is a filter feeder and sieves plankton through its gills as it swims. It also feeds on fish, squid, and pelagic crustaceans by opening its huge mouth.
  • Whale sharks have 5 large gill slits and the first gill slit (spiracle), which is used for breathing when the shark is resting on the sea floor, is located directly behind the shark's eye.
  • This species can weigh up to 15 tons, and like most sharks, females are larger than males.
  • Whale sharks have about 3,000 tiny teeth, which are of little use.
  • This shark can process >1,500 gallons of water each hour.
  • Whale sharks are solitary species but at 30 years they begin mating.
  • This shark can live to an age of 100 - 150 years.

Threats

  • It is thought that the most significant threat to whale sharks is habitat loss or degradation in the form of overfishing of reef fish, coastal development, land-based pollution, increased boat traffic and noise pollution.
  • Fishing for meat and fins, harassment and boat strikes also pose serious threats to whale sharks.
  • Although whale sharks are protected under CITES, in some areas fisheries remain and continue to carry high prices.

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