The whale shark is one of only three varieties of filter-feeding sharks (the basking and megamouth are the others). The species also is closely related to the bottom-dwelling sharks (Orectolobiformes), which include the wobbegong. There are no reliable estimates of the worldwide whale shark population, and the International Union for the Conservation of Nature lists the species as "vulnerable." Prior to the mid-1980s, there were only about 350 recorded sightings of whale sharks worldwide, but in recent years, with an increase in recreational diving and boating and ecotourism, sightings have become much more numerous. Whale sharks have been seen off the coasts of India, the Maldives, South Africa, Belize, Mexico, the Galapagos Islands, Southeast Asia and Indonesia, among other places.
While whale sharks' massive bodies might make them seem like scary super-predators, they pose no danger to humans or large mammals or fish. Instead, they dine upon krill, zooplankton, crab spawn, squid,and small fish such as sardines, anchovies, and mackerel. Instead of biting its food, like a great white, the whale shark juts out its big jaws and sucks in the water around it. It then shuts its mouth, forcing the water to filter through its gills. Everything that remains in its filters becomes the giant creature?s dinner. The whale shark itself is preyed upon by fishermen in some Asian countries, though catches have been decreasing in recent years, according to the IUCN.
Relatively little is known about many key aspects of whale shark behavior. Most of the sightings are of juvenile males in coastal areas, where they gather to feed. But adult whale sharks' precise movements remain mysterious. They are believed to spend much of their time in the ocean deep, far from shore, going on long, multi-year journeys, during which they visit areas that are richer in food. Knowledge about whale shark migration comes from a variety of sources, including acoustic tracking, satellite tracking, tagging and photo identification.
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