In Kiswahili the whale shark is called “papa shillingi”, translating as “shark covered in shillings”. There is a local legend that God was so pleased when he created this beautiful fish, that he gave his angels handfuls of gold and silver coins to throw down from heaven onto its back. So it goes that whale sharks have their magical markings and swim near the surface, catching the sun on their backs, as a way of saying thank you
to their maker.
The whale shark (Rhincodon typus) is a relatively recent addition to the human record of the ocean and its inhabitants. However, the ancestry of this shark goes back to the Jurassic and Cretaceous periods 245-65 million years ago, when the present groups of sharks began to appear. It was not until 1828 when the first whale shark specimen known to science was discovered off the South African coast. Dr Andrew Smith formally described this species later that year as the largest living shark in the ocean. This species is rare. Prior to the mid-1980's, there had been less than 350 confirmed reports of whale sharks worldwide. Since this time, consistent sightings have been recorded in Australia. A lucrative ecotourism industry revolving around their annual appearance at Ningaloo Marine Park on the Western Australian northwest coast is now well established.
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.
Primarily solitary creatures, they occasionally gather in all-male or all-female groups that are often segregated according to size and age. Seasonal aggregations have been sighted offshore in Belize, Mexico, the Seychelles, Honduras, Mozambique, Kenya, Djibouti, the Philippines, Australia, and the Maldives. These groups can reach 400 animals in number. Together they feed on seasonal pulses of food, such as thick “soups” of plankton like the copepod blooms off Baja, Mexico or reef fish spawning aggregations in Belize.
Although there is little information on the life history of Whale Sharks, data from the few individuals that have been tracked has accounted for most of the accepted theories at present. Whale Sharks are highly migratory and consequently utilise a vast habitat (the longest recorded Whale Shark journey spanned 13 000 km and took over 36 months). Their movements are probably food driven and linked to plankton blooms and invertebrate and fish spawning events (Colman 1997). There is evidence too that Whale Sharks separate both by size and sex and mix only when mating although this cannot be confirmed as no Whale Shark mating site has been found (Eckert & Stewart, 2001).
The whale shark has a pelagic habitat. Whale sharks appear to prefer locations with surface water temperatures between 21 -25 degrees, where cool nutrient-rich upwellings mingle with warm surface waters of salinities between 34-34.5%. These conditions may well be optimal for the production of the planktonic and nektonic prey upon which the sharks feed.
Like bottom-dwelling sharks, the whale shark has twin nasal slits and sensory barbells (a trait it shares with the nurse shark) in front of its blunt snout on the upper surface above the mouth. In sharks, the nasal openings do not lead to the mouth nor do they play any part in respiration, their purpose is to augment the shark's sense of smell, enabling it to detect prey without relying on sight.
The eye of the whale shark is relatively small for a creature that spends much of its life in the dark depths of the ocean, suggesting that eyesight is not an important sense. It would be hard for the shark to locate its tiny prey with eyesight alone. The shark does not have any eyelids, but is able to withdraw the eye into the head, rotating it as it does so, as a protective measure.
The whale shark has distinctive light-yellow markings (random stripes and dots) on its very thick dark gray skin. Its skin is up to 4 inches (10 cm) thick. There are three prominent ridges running along each side of the shark's body. It has a wide, flat head, a rounded snout, small eyes, 5 very large gill slits, 2 dorsal fins (on its back) and 2 pectoral fins (on its sides). The spiracle (a vestigial first gill slit used for breathing when the shark is resting on the sea floor) is located just behind the shark's eye. Its tail has a top fin much larger than the lower fin.
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.