Is a whale shark a whale or a shark?

November 1998

Whale sharks are fish, the largest fish in the world. They are named for their massive size. In 1919, a whale shark estimated at 60 feet long was caught in the Gulf of Thailand. It was so large fishermen were unable to haul it ashore and no measurements were taken. The largest accurately measured whale shark was a 40-foot, 7-inch male caught in Bombay, India, in 1983. Its mouth measured more than 4 feet wide and  pectoral fins more than 6 feet long.

The whale shark’s (Rhiniodon typus) feeding method is similar to that of some whales. It strains small crustaceans and fishes out of the water with sieves on its large gills. Like sharks, the whale shark has tough skin and is coldblooded.

Even though it feeds by straining water, this giant fish has several thousand teeth in about a dozen rows in its jaws. Each tooth is only one-twelfth of an inch long. When feeding, the whale shark  sometimes stops swimming and appears to stand vertically on its tail.

This aquatic titan is gray-brown to reddish or greenish in color and distinguished by a unique, checkered pattern of whitish spots and bars. Its shape is somewhat different from other shark species. Its head is wider and it has a humped back and a large crescent-shaped tail.

Whale sharks prefer temperate or tropical water, but are found in the open sea worldwide. In the Atlantic, they range as far north as New York to as far south as Brazil. Divers often refer to these massive creatures as “gentle giants.” Whale sharks are listed as vulnerable on the International Union of Conservation and Nature (IUCN) Red List.