The Whale shark
The whale shark (Rhincodon typus) is a slow-moving filter feeding shark and the largest known extant fish species. The largest confirmed individual had a length of 12.65 m (41.5 ft) and a weight of about 21.5 t (47,000 lb), and unconfirmed reports of considerably larger whale sharks exist. Claims of individuals over 14 m (46 ft) long and weighing at least 30 t (66,000 lb) are not uncommon. The whale shark holds many records for sheer size in the animal kingdom, most notably being by far the largest living nonmammalian vertebrate. It is the sole member of the genus Rhincodon and the family, Rhincodontidae (called Rhiniodon and Rhinodontidae before 1984), which belongs to the subclass Elasmobranchii in the class Chondrichthyes. The species originated about 60 million years ago.
The whale shark is found in open waters of the tropical oceans and is rarely found in water below 22 °C (72 °F). Modeling suggests a lifespan of about 70 years, but measurements have proven difficult. Whale sharks have very large mouths and are filter feeders, which is a feeding mode that occurs in only two other sharks, the megamouth shark and the basking shark. They feed almost exclusively on plankton and therefore, are completely harmless to humans.
The species was distinguished in April 1828 after the harpooning of a 4.6 m (15 ft) specimen in Table Bay, South Africa. Andrew Smith, a military doctor associated with British troops stationed in Cape Town, described it the following year. The name "whale shark" comes from the fish's size, being as large as some species of whales and also that it is a filter feeder like baleen whales.