Whale Shark

The Most Gentle of Giants The whale shark is a slow filter feeding shark that is the largest living fish species. This shark is found in tropical and warm oceans and lives in the open sea. They are slow swimmers.This species is believed to have originated about 60 million years ago.

This species was first identified in April 1828 following the harpooning of a 15.1 ft specimen in Table Bay, South Africa. The name "whale shark" comes from the fish's psysiology; tht is, a shark as large as a whale that share a similar filter feeder eating mode. The largest specimen regarded as accurately recorded, was caught on November 11, 1947 in Pakistan. It was 41.5 feet long and weighed more than 47,300 pounds, with a girth of 23 feet.

As a filter feeder, it has a capacious mouth which can be up to approximately 5 feet wide and can contain between 300 and 350 rows of tiny teeth. It has 5 large pairs of gills. Two small eyes are located towards the front of the shark's wide, flat head. The body is mostly gray with a white belly, and the skin is marked with a "checkerboard" of pale yellow spots and stripes. These spots are unique to each whale shark.

The whale shark is a filter feeder (one of only 3 known filter feeding shark species; basking shark and megamouth shark). It feeds on phytoplankton, macro-algae, plankton, krill, and small nektonic life (such as small squid or vertebrates).

How Filter Feeding Works:

1. The many rows of teeth play no role in feeding; in fact, they are reduced in size in the whale shark. Instead, the shark sucks in a mouthful of water, closes its mouth and expels the water through its gills.
2. During the slight delay between closing the mouth and opening the gill flaps, plankton is trapped against the dermal denticles which line its gill plates and pharynx.
3. 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 (anything above 2 to 3 mm in diameter is trapped)
4. Any material caught in the filter between the gill bars is swallowed.
5. Interesting fact: Whale sharks have been observed "coughing". It is presumed that this is a method of clearing a build up of food particles in the gill rakers.

This species, despite its enormous size, does not pose any significant danger to humans. It is a frequently cited example when educating the public about the popular misconceptions of all sharks as "man-eaters". They are actually quite gentle and can be playful with divers. There are unconfirmed reports of sharks lying still, upside odwn on the surface to allow divers to scrape parasites and organisms from their bellies. Divers and snorklers can swim with this giant fish without any risk apart from unintentionally being struck by the shark's large tail fin.

Check out the whale shark in motion:
http://www.youtube.com/watch?v=uQrBwN39LJI
http://www.youtube.com/watch?v=KgW7hqhUigM
http://www.youtube.com/watch?v=1vMeTVWdhls&feature=related