Orectolobiformes Rhincodontidae

Jeff Guertin 10/09/07

One Genus

 Only one genus and species, Rhincodon typus, also known as the whale shark  Etymology: Greek, rhyngchos = snout, muzzle + Greek, odous, odontos = tooth, teeth  First identified in 1828  Believed to be about 60 million years old

General Characteristics

 Five large gill openings, the fifth behind origin of pectoral fin  Elongated gill rakers  Blunt head with terminal mouth  Reduced teeth (up to 300 rows)  Two dorsal fins, one anal fin, no dorsal or anal spines  Broad snout

Distinctive Features

Distinctive Features

      A unique color pattern of light spots and vertical and horizontal stripes, in the form of a checkerboard World’s largest fish (maximum reported length 13.7 m) No subterminal notch on caudal fin Pattern of spots and stripes unique to each animal Large first and small second dorsal fin Very large pectoral fins (much larger than pelvic)

Distinctive Features

Habitat

 Inhabit tropical and subtropical habitats circumglobally  Primarily pelagic with coastal feeding aggregations at times (migrations)  Up to 700m  Usually solitary, but found in feeding aggregations of over 100 individuals  Males range over larger distances than females

Habitat

Food Habits

 Feeds on planktonic and nektonic prey, such as small fishes (sardines, anchovies, mackerel, juvenile tunas and albacore), small crustaceans and squids  Have homodont teeth (all the same shape and no abrupt change in size) which is rare for sharks  No nictitating membrane; use the extraocular muscles to rotate the entire eye back into the orbit to protect it from abrasion during feeding

Food Habits

 Ram filter feeders

Food Habits

  Can hang vertically in the water column, where they will suck prey into the mouth or rise vertically out of the water and sick back under creating an inflow of water and prey into their mouths Whale sharks are highly migratory, with their movements probably timed with blooms of planktonic organisms and changes in temperatures of water masses   During March and April, they aggregate on the continental shelf of central western Australian coast in response to coral spawning events that occur each year Make regular oscillations between the surface and the bottom off the coast, probably to search for food throughout the water column

Food Habits

Size, Age, Growth

  Average size is 8m, can grow up to 12.5m; largest specimen regarded as accurately recorded was caught in 1947 near India (12.65m, ~47,00lbs)  Reports of specimen as large as 18m Little known about age and growth rates   Age estimates unknown, but thought to be well over 60 years (maybe upwards of 100) Females as large as 8-9m have been found to be immature

Reproduction

 Originally thought to be oviparous, but in 1995 a female was harpooned off the coast of Taiwan which showed that they are ovoviviparous; litter size was over 300 pups  Sex ratio was about 1:1  Give birth to pups 40-60cm big  Sexual maturity estimated at 30 years of age, but really unknown

Predators

    Some whales and dolphins (killer whales) A juvenile specimen was found in the stomach of a blue shark (Prionace glauca). Another specimen was found in the gut contents of a blue marlin (Makaira nigricans). Many parasitic copepods were found on the lining of the pharynx of a small (60cm total length) whale shark from Taiwan. Humans

Conservation

    Status is vulnerable Utilized fresh, frozen, dried and salted for human consumption, liver processed for oil, fins used for shark-fin soup, cartilage for health supplements and skin for leather products Used in Chinese medicine Large size, slow growth, and late maturation limit recruitment and make whale sharks susceptible to overexploitation.

With golden pilot jacks Remoras inside the cloaca of a female http://youtube.com/watch?v=dUM USFLyZpU (remora catching a free ride) Swimming with a diver

Bibliography