Averaging in length to more than 7.6 m (25 feet), whale shark is the biggest fish in the world. They feed on macro-algae, plankton, krill, red crab larvae, and small nektonic life such as small squid or vertebrates. Like sharks, its skeleton is composed entirely of cartilage, and its skin, up to 4 inches thick, is scaleless, tough and leathery. People called it a whale shark because of its enormous size.
Whale sharks are filter feeder. Using it’s 1.5 metres (4.9 ft) mouth, they feed by sucking in a mouthful of water then closes its mouth and expels the water through its gills – trapping the tiny planktons in the dermal denticles which line its gill plates and pharynx. This fine sieve-like apparatus can trap anything above 2 to 3 millimetres (0.079 to 0.12 in) in diameter.
Despite it’s ferocious look and size, Whale sharks are gentle giants. Apart from unintentional blows with it’s large tail fin, they does not pose significant danger to humans and even sometimes allow swimmers, divers and snorkelers, to hitch a ride.
The largest Whale shark specimen was caught near Baba Island, in Karachi, Pakistan on November 11, 1947. It was 12.65 metres (41.50 ft) long, weighed more than 21.5 tonnes (47,000 lb), and had a girth of 7 metres (23.0 ft). Though there are stories of even larger ones, there are no scientific evidence that support it.