Orectolobiformes Rhincodontidae

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Orectolobiformes Rhincodontidae

• Jeff Guertin
• 10/09/07

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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

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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

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Distinctive Features
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Distinctive Features

• A unique color pattern of light spots and
  vertical and horizontal stripes, in the form of a
  checkerboard
• Worlds 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)

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Distinctive Features
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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

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Habitat
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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

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Food Habits

• Ram filter feeders

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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

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Food Habits
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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

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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 11
• Give birth to pups 40-60cm big
• Sexual maturity estimated at 30 years of age, but
  really unknown

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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

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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.

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Remoras inside the cloaca of a female
With golden pilot jacks
Swimming with a diver
http//youtube.com/watch?vdUMUSFLyZpU (remora
catching a free ride)
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Bibliography