WHALE SHARK

The species was first identified in April 1828 following the harpooning of a 4.6 Meter (15.1 ft) specimen in Table Bay, South Africa. It was described the following year by Andrew Smith, a military doctor associated with British troops stationed in Cape Town, He proceeded to publish a more detailed description of the species in 1892. The name "whale shark" comes from the fish's physiology; that is, a shark as large as a Whale that shares a similar filter feeder eating mode.

LOCATION FOUND

Kingdom: Animalia
Phylum: Chordata
Class: Chordrichthyes
Subclass: Elasombranchii
Order: Oretolbiformes
Family: Rhincodontidae
(Muller and Henle, 1893) Genus: Rhincodon
Smith, 1829 Species: R. typus

As a Filter Feeder, it has a capacious mouth which can be up to 1.5 metres (4.9 ft) wide and can contain between 300-350 rows of tiny teeth.As a filter feeder, it has a capacious mouth which can be up to 1.5 metres (4.9 ft) wide and can contain between 300-350 rows of tiny teeth. It has five large pairs of gills. Two small eyes are located towards the front of the shark's wide, flat head. The body is mostly grey with a white belly; three prominent ridges run along each side of the animal and the skin is marked with a 'checkerboard' of pale yellow spots and stripes These spots are unique to each whale shark and because of this they can be used to identify each animal and hence make an accurate population count. Its skin can be up to 10 centemeters (3.9 in) thick. The shark has two pairs each of dorsal fins, and pectoral finsA juvenile whale shark's tail has a larger upper fin than lower fin while the adult tail becomes semi-lunate (or crescent-shaped). The whale shark's spiracles are just behind the eyes

The whale shark is not an efficient swimmer since the entire body is used for swimming, which is unusual for fish and contributes to an average speed of only around 5 kilometres per hour. The largest specimen regarded as accurately recorded was caught on Nov/11 1947 near the island of Baba, not far from Karachi, Pakistan It was 12.65 metres (41.5 ft) long, weighed more than 21.5 tonnes (47,300 lb), and had a girth of 7 metres (23 ft).(5) Stories exist of vastly larger specimens - quoted lengths of 18 metres (59 ft) are not uncommon in the popular shark literature - but no scientific records exist to support their existence. In 1868 the Irish natural scientist E. Perceval Wright spent time in the Seychelles,, during which he managed to obtain several small whale shark specimens, but claimed to have observed specimens in excess of 15 metres (49.2 ft), and tells of reports of specimens surpassing 21 metres (68.9 ft).

In a 1925 publication, Mark Hugh Smith. describes a huge whale shark caught in a bamboo fish trap in Thailand in 1919. The shark was too heavy to pull ashore, but Smith estimated that the shark was at least 17 metres (56 ft) long, and weighed approximately 37 tonnes (81,500 lb), which have been exaggerated to an accurate measurement of 17.98 metres (58.99 ft) and weight 43 tonnes in recent years. There have even been claims of whale sharks of up to 23 metres (75 ft). In 1934 a ship named the "Maurguani" came across a whale shark in the Southern Pacific ocean, rammed it, and the shark consequently became stuck on the prow of the ship, supposedly with 4.6 metres (15.1 ft) on one side and 12.2 metres (40 ft) on the other. No reliable documentation exists of those claims and they remain little more than "fish-stories".

DIET
The whale shark is a filter feeder - one of only three known filter feeding shark species (along with the basking-shark and the mega-mouth). It feeds on Phytoplankton, macro-Algae Plankton., Krill and small Nektonic, life, such as small Squid.or Verebrates.. 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. During the slight delay between closing the mouth and opening the gill flaps, plankton is trapped against the Dermal Dentix. which line its gill plates and Pharynx 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). Any material caught in the filter between the gill bars is swallowed. Whale sharks have been observed "coughing" and it is presumed that this is a method of clearing a build up of food particles in the gill rakers.

Behaviour towards divers
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. Divers and snorkellers can swim with this giant fish without any risk apart from unintentionally being hit by the shark's large tail fin.
Conservation status
The whale shark is targeted by artisinal and Commercial fisheries in several areas where they seasonally aggregate. The population is unknown and the species is considered vulnerable by the IUCN. Whale sharks are known to frequent the waters off Donsol in the Sorsogon province of the Philippines.

D. BROWN.