Coelacanth – everyone’s favourite fossil fish

Fishermen from Southeast Asia and eastern Africa had been catching them them for years, and throwing them back for just as long, because they aren’t fit to eat. Then in 1938, a young museum curator, named Marjorie Courtenay-Latimer, spied one on the docks in South Africa.  It was the first recently-dead Coelacanth seen by someone who was able to understand the significance of the find.

Latameria chalumnae

Latimeria chalumnae became famous as the only living species of a group of fish that were considered the progenitors of all tetrapod life. More recently, Latimeria menadoensis, a closely related species has been identified. Previous to this, Coelacanths had only been known as fossils with a lineage dating from 380 to 65 million years ago. They belong to a group known as the sarcopterygians or lobe-finned fish, that have the unique feature of possessing fins consisting of bone structures similar to tetrapods, and the ability to move them in a way that enables them to ‘walk’. Some, such as Eusthenopteron foordi developed rudimentary lungs, enabling them to begin the movement for colonization of terrestrial environments.

The discovery of this ‘fossil fish’ has often been used by creationists to bolster their claim that an animal that hasn’t changed in all that time disproves the theory of Evolution.This claim ignores the fact that L. chalumnae and L. menadoensis are thoroughly modern fish that have descended from the earlier forms, in much the same way Homo sapiens sapiens evolved from earlier primate and homo species. There are at least 47 genera of sarcopterygians known, with only these two extant.   Changes from fossilized fish include alterations in the vertebrae, skull, and musculature.

Hans Fricke has spent 40 years studying the Coelacanth, and has some new information about this fascinating fish.

Coelcanths are the night walkers, avoiding venturing out during the daylight. They rarely venture far from a home series of caves and within this home area may reside in multiple caves. There exist a “local knowledge” of preferred caves. Many suitable caves in the home area often go inhabited.

Fricke and others have determined that the coelacanth is a fish of records. The daily food intake and metabolic demands of this fish are the lowest among all vertebrates. The formation and development of the coelacanth embryo extends for three years, the longest of any vertebrate. At birth, juveniles already measure 35 centimeters in length.

Oviparous birth is another of the evolved characteristics of these species, with as many as 2 dozen offspring per birthing. The female is the larger, reaching 1.8 m in length, while the males are only about 1.3 m.

Over the lifespan of a coelacanth, possible reaching over a century, there is little risk of mortality. Indeed, coelacanths possess one of the lowest natural death rates of any vertebrate. No natural predators of the coelacanth are known.

Unfortunately, I do not have access to the complete paper, but if anyone does, it can be found here.

Fricke, H., Hissmann, K., Froese, R., Schauer, J., Plante, R., & Fricke, S. (2011). The population biology of the living coelacanth studied over 21 years Marine Biology DOI: 10.1007/s00227-011-1667-x

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One Response to Coelacanth – everyone’s favourite fossil fish

  1. Tineke Prins says:

    Is it possible to use the picture of de coelacanth in our scientific (Dutch) magazine? (Named Visionair)

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