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Coelacanth

[sEl' uh kanth] Latimeria chalumnae

coelacanth

Description

The coelacanth is the only living animal to have a hinged joint in the skull, which allows the front part of the head to be lifted whilst feeding. Other unique features include a receptor in the rostral (sense) organ of the head which can detect electric fields and may be used to locate prey or monitor its surroundings; an oil-filled tube, called a notochord, which serves as a backbone; thick scales common only to extinct fish; paired lobe fins that extend away from its body like legs and move in an alternating pattern, like a trotting horse; and a tail consisting of three distinct lobes. The coelacanth is also noted as particularly mucilaginous; not only do the scales exude mucus, but their bodies continually ooze a large quantity of oil.

The scaly body is dark blue or brown in color with white speckles, the pattern of which is unique to each individual and provides good camouflage against cave walls. Coelacanths can be up to 6.5 feet long and weigh up to 198 pounds.

Distribution and Habitat

Once believed to have gone extinct about 65 million years ago, the first living coelacanth specimen was discovered in 1938 off the coast of South Africa. Until recently the only known population was located in the Comoro Islands, a small archipelago in the Mozambique Channel. Since then however, coelacanths have been observed off the northeast coast of South Africa in Sodwana Bay, as well as off Madagascar, Kenya and Tanzania. Individuals caught in Indonesian waters are currently considered a distinct species (Latimeria menadoensis) and are brown in color.

Coelacanths live at depths of 490-2,300 feet, where there are submarine caverns, deep reefs, and volcanic slopes, but have also been tracked at depths of just 55 feet.

The coelacanth is listed as critically endangered, with deep-sea fishing being the greatest threat to its survival.

Diet

Coelacanths are opportunistic drift-feeders, preying mainly on fish, eels, and skates.

Reproduction

The courtship and mating rituals of the coelacanth have never been studied, but the capture of pregnant females proves that fertilization and egg development are internal. The average number of pups born per litter is unknown, but one female had 26 well-developed embryos in her when she was caught.

Coelacanths appear to be very long-lived and some scientists believe them to live as long as 80 years.

Other Habits and Behaviors

Coelacanths appear to be most active at night, spending the day hovering in submarine caves and foraging along the coast at night. Individuals observed in the wild appear to occasionally swim with their heads down in a "headstand" posture, but this may be a result of the light or electromagnetic field produced by the observing submarine.

Scientists suspect that one reason Latimeria has been so successful (and also long-lived) is that they can slow down their metabolisms at any time, sinking into the less-inhabited depths and minimizing their nutritional requirements in a sort of hibernation mode.

Scientific Classification

phylum Chordata
class Sarcopterygii
order Coelacanthiformes
family Latimeriidae
genus & species Latimeria chalumnae

SOURCES
Arkive www.arkive.org/coelacanth/latimeria-chalumnae/
Dinofish www.dinofish.com/
MarineBio marinebio.org/species.asp?id=54
National Geographic animals.nationalgeographic.com/animals/fish/coelacanth/
National Museum of Natural History vertebrates.si.edu/fishes/coelacanth/coelacanth_wider.html

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The Robinson Library >> Science >> Zoology >> Fishes >> Class Sarcopterygii

This page was last updated on October 30, 2017.