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All Creatures,

Episode 23: It’s not a Whale, it’s a Whale Shark

April 10, 2018

 

Whale sharks are the largest fishes in the world. They swim throughout the world’s oceans and are a fish, not a whale. The fishes of the world breath through a set of gills to receive oxygen for their bodies. Whales are mammals and need to breath air, which they do through their blowholes when they surface. Further, fish have a caudal fin (back fin) that goes up and down, whereas whales have a fluke that is flat.

Whale Shark Overview

Whale sharks (Rhincondon typus) are found in warm and temperate oceans throughout the world. These animals are called “pelagic,” which means they are animals that live in the open ocean, and not specific to reefs or coastal waters. Interestingly, whale sharks are known to migrate and they are some ‘hot spots’ around the planet that tourists gather to view these creatures.

There are two recognized sub-species of whale sharks. Once the isthmus of modern-day Panama closed off millions of years ago, these two different populations evolved from each other forming an Atlantic subpopulation and an Indo-Pacific population.

Of the 440 species of sharks, Whale sharks are 1 of the 3 that are recognized as filter feeders. The other two species are: Basking sharks and Megamouth sharks.

Whale Shark Facts

  • Can reach as long as 40 feet (12.5 meters)
  • Mouths are as large as 5 feet (1.5 meters) across
  • Can live up to 100 years in the wild
  • Outside of Asia, only Whale sharks kept captive are at the Georgia Aquarium in Atlanta
  • They have two methods of feeding, the passive feeding in which they just swim with their mouths open and filter out the food and the active/vertical feeding which uses suction to draw large quantities of water
  • Eat plankton, krill, small marine life such as fish larvae, and eggs from fish, corals and invertebrates
  • During feeding the shark draws in a mouthful of water and and pushes this water through dense filters on the internal gills, This fine sieve-like apparatus, which is a unique modification of the gill rakers, prevents the passage of anything but fluid out through the gills, catching anything above 2 to 3 millimetres (0.079 to 0.12 in) in diameter

Whale Shark Conservation

Whale Sharks are now classified as endangered.

It is now estimated the great Pacific garbage patch is as large as two-times the size of Texas. This is just one challenge for the whale shark. Additionally, over 100 million sharks are killed per year for nothing more than their fins for ‘shark fin’ soup, to include whale sharks. Quite often, whale sharks are caught in fishing nets and drown. Current populations of whale sharks are in serious decline.

The Atlantic Whale shark population is estimated to be at least 30% lower than what they were 75 years ago. Data is often collected by tuna fisherman who look for whale sharks who feed near tuna. Once they would see 4 to 6 sharks per day in 1998. Today, most report seeing 1 to 2 Whale sharks per day.

The Indo-Pacific Whale shark population is in serious decline. It is estimated these populations have declined more than 63% over the past 75 years. This is an area where shark fishing, the large garbage patch, and other pressures have led to their decline.

Conservation Tips

Share this knowledge, reduce the use of plastic, reduce wasting of water. Help preserve our oceans.

Organizations to Support

Whale Shark & Oceanic Research Center

Maldives Whale Shark Research Program

Video Links

Whale Shark swimming

Whale Shark rescue

Whale Shark information

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