A whale shark (Rhincodon typus).
Whale sharks are often accompanied by remoras.
© J. Stafford-Deitsch
Whale sharks are the largest sharks of their kind, but despite their size they are
completely harmless. Their behavior is characterized by slow swimming movements in
their search for food on the water's surface. Unfortunately, exactly this behavior has
been the sharks' undoing over the past years for it made them susceptible to easy
slaughtering in great numbers. Accordingly, a market was also developed. Once again
repulsive finning was the reason these animals had to die. In Taiwan there is a huge
market for this shark species which is sold under the name "Tofu shark". Various
measures are now under way to protect these animals and several countries have already
met with success. However, these animals are very migratory, swimming beyond
territorial boundaries, so obviously appropriate agreements for their protection must
be concluded with neighboring countries.
The animal's basic color is gray,
blue or brown with light vertical stripes and white dots over the entire body. Very
striking is their horizontal mouth which is not located underneath the snout as with
typical sharks (ventral), but rather terminal. Also typical for these animals is an
extreme angular head form. Since whale sharks are related to nurse sharks (e.g.
Ginglymostoma cirratum), they have relatively small eyes, spiracles and barbels.
Their size and weight are a matter of speculation. The longest female ever
measured was found stranded near Mangalore (India) and had a length of 12.1 m. The
largest male was of the same length and was found near Bombay (India). Photographic
indices, however, allow a guess that even larger animals exist. Weight details are
barely available. The heaviest speciman ever found (in March 1994) weighed 36,000 kg.
Whale sharks are active filterers, meaning they actively suck in water. Their
preferred food is plankton which is filtered through the gills. Since the animals
prefer plankton bloom they tend to swim in water temperatures between 21°C and 25°C.
Although mostly found in deeper water (epipelagic), they have also been observed in
atolls and reef regions. In addition to plankton they also eat smaller and larger fish
(e.g. sardines, mackerels and even small tuna fish). An interesting fact is that whale
sharks often eat while in a vertical position.
Whale sharks are viviparous, but they have no yolk placenta (aplacentally viviparous).
The often found
huge egg capsules are simply premature pups. Whale sharks thus do not lay eggs. The
offspring are born in the mother's body out of egg capsules. Up to 300 young have been
counted in one female. Their size at birth lies between 55 and 64 cm. The females
appear to give birth during the entire year because the young have been found both in
winter and in summer in single regions. One reason for the low catch in young animals
appears to be due to their quick growth. Despite their size, they reach sexual
maturity when they have a length of approximately 400 cm.
Whale sharks demonstrate an almost worldwide distribution in
tropical and subtropical oceans, both
in coastal regions as well as in the open sea.
Whale sharks are
harmless and humans can approach them without any risk as long as they avoid molesting
Whale sharks are often accompanied by remoras which either
actively swim with, or suck themselves onto the whale shark. In addition to their
using the shark as a means of transportation, one of their main functions is to remove
parasites. Since whale sharks are very large animals, it is very likely that these
bony fish also swim into the mouth or spiracle of the whale. Nor is it surprising that
they have been seen to look out of the anus.
May be published only by indicating the source: Shark Info / Dr. Erich K. Ritter