The whale shark (Rhincodon typus) is a species of carpet shark and the largest fish known. The largest confirmed individual had a length of 12.65m and a weight of 21.5t. The whale shark is found in open waters of the tropical oceans and is rarely found in waters below 70 °F. Modeling suggests a lifespan of about 70 years, but measurements have proven difficult.
Whale sharks have a mouth that can be 1.5m wide, containing 300 to 350 rows of tiny teeth and 10 filter pads which it uses to filter feed. Unlike many other sharks, whale sharks’ mouths are located at the front of the head rather than on the underside of the head. Whale sharks have five large pairs of gills. The head is wide and flat with two small eyes at the front. Whale sharks are grey with a white belly. Their skin is marked with pale yellow spots and stripes which are unique to each individual. The whale shark has three prominent ridges along its sides. Its skin can be up to 10cm thick. The shark has a pair of dorsal fins and pectoral fins. Juvenile whale shark’s tails have a larger upper fin than the lower fin, while the adult tail becomes semilunate.
The whale shark is a filter feeder – one of only three known filter feeding shark species (along with the basking shark and the megamouth shark). According to Wikipedia, “whale sharks feed on plankton including copepods, krill, fish eggs, Christmas Island red crab larvae and small nektonic life, such as small squid or fish. It also feeds on clouds of eggs during mass spawning of fish and corals. The many rows of vestigial teeth play no role in feeding. Feeding occurs either by ram filtration, in which the animal opens its mouth and swims forward, pushing water and food into the mouth or by active suction feeding, in which the animal opens and closes its mouth, sucking in volumes of water that are then expelled through the gills.”
Despite its size, the whale shark does not pose a significant danger to humans. Whale sharks are docile fish and sometimes allow swimmers to catch a ride, although this practice is discouraged by shark scientists and conservationists because of the disturbance to the sharks. Younger whale sharks are gentle and can play with divers. Underwater photographers such as Fiona Ayerst have photographed them swimming close to humans without any danger.
The whale shark is marked as endangered on the IUCN Red List due to overfishing, vessel strikes and more.
Because of its iconic status, the whale shark is popular in the few public aquariums that keep it, but its large size means that a very large tank is required and it has specialized feeding requirements. Their large size and iconic status have also fuelled an opposition to keeping the species in captivity, especially after the early death of some whale sharks in captivity and certain Chinese aquariums keeping the species in relatively small tanks.