The coelacanth was found to be 'alive and well' in 1938 after millions of years of hiding, but is he really a 'living fossil'?
The genus Latimeria (the coelacanths) has only two known living representatives. These are Latimeria chalumnae and Latimeria menadoensis . They both live in deep water (one off the coast of Africa and the other in Indonesian waters). The two species diverged a long time ago, maybe as much as 40M years, and their ancestors are known from the fossil record for as far back as 400M. But are they really ‘living fossils’?
I would argue that every creature alive today is equally ‘modern’. The coelacanth developed his body-form a long time ago, but surely he has been evolving ever since – just like the rest of us? There are no known fossils of the two living species, and all we have is their relatives. It is true that their closest relative disappeared from the fossil record about 70M years ago, before the dinosaurs were even thought about, and that other very close relatives of the coelacanth ‘came ashore’ about 360M years ago, and are possibly our ancestors. But does that mean that the coelacanths are our ancestors? The answer, to my mind, is a resounding no. Nothing alive today could possibly be our ancestor and while it is true that their ancestors were also ours, you could say that for any living thing if you go back far enough!
Modern coelacanths do resemble us in a few ways. They are big, about as long as we are tall – and about the same weight. They can live for about 60 years, and only become sexually mature at 20. Each one has unique markings, and they are recognisable as ‘individuals’. Coelacanth fins look like primitive legs (hence ‘old four-legs’), and they have the remains of an early ‘lung’. But they live in another world!
Coelacanths spend most of their time in deep water (100-300m) eating squids and the like, which they find using their ‘electric sense’. When times get hard they sink into deeper water and ‘hibernate’. Coelacanths rarely move into shallow waters and therefore not many have been seen by scientists (about 200 individual fish so far). Local fishermen have probably caught and eaten far more, or simply thrown them away since they are said to taste horrible!. It is thought that there are very few of either species alive today (maybe only 1000), so we could easily ‘lose’ them if deep-water trawling continues unchecked.
More information, plus some nice animations and a ‘time-line’ can be found at: http://www.dinofish.com/ .
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