The whale shark (Rhincodon typus) is a slow-moving filter feeding shark and the largest known extant fish species. The largest confirmed individual had a length of 12.65 m (41.50 ft) and a weight of more than 21.5 metric tons (47,000 lb), and unconfirmed reports of considerably larger whale sharks exist. Claims of individuals over 14 m (46 ft) long and weighing at least 30 mt (66,000 lb) are not uncommon. The whale shark holds many records for sheer size in the animal kingdom, most notably being by far the largest living nonmammalian vertebrate, rivalling many of the largest dinosaurs in weight. It is the sole member of the genus Rhincodon and the family, Rhincodontidae (called Rhiniodon and Rhinodontidae before 1984), which belongs to the subclass Elasmobranchii in the class Chondrichthyes. The species originated about 60 million years ago.
As the largest fish in the sea, reaching lengths of 40 feet (12 meters) or more, whale sharks have an enormous menu from which to choose. Fortunately for most sea-dwellers—and us!—their favorite meal is plankton. They scoop these tiny plants and animals up, along with any small fish that happen to be around, with their colossal gaping mouths while swimming close to the water's surface.
The whale shark, like the world's second largest fish, the basking shark, is a filter feeder. In order to eat, the beast juts out its formidably sized jaws and passively filters everything in its path. The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales.
The whale shark's flattened head sports a blunt snout above its mouth with short barbels protruding from its nostrils. Its back and sides are gray to brown with white spots among pale vertical and horizontal stripes, and its belly is white. Its two dorsal fins are set rearward on its body, which ends in a large dual-lobbed caudal fin (or tail).
Preferring warm waters, whale sharks populate all tropical seas. They are known to migrate every spring to the continental shelf of the central west coast of Australia. The coral spawning of the area's Ningaloo Reef provides the whale shark with an abundant supply of plankton.
Although massive, whale sharks are docile fish and sometimes allow swimmers to hitch a ride. They are currently listed as a vulnerable species; however, they continue to be hunted in parts of Asia, such as the Philippines.
And here are two pictures of my recent adventure snorkeling with Whale Sharks in Baja California!