Saturday, 10 December 2016

Creatures Of The Deep: The Coelacanth

Put down your fish knives and forks, good people, the coelacanth is not for eating. It's not officially a protected species, though it probably should be. The fact is, it just doesn't taste very nice.

Thought to be extinct for 65 million years, this stunning  creature of the deep amazed the whole scientific community when it broke cover and resurfaced on Christmas Eve in 1938 off the coast of south-east Africa. Here it is pictured below, looking slightly worried and possibly a tad apologetic, but nonetheless charming for that. So what's the story?

The coelacanth - happy to be still around after over 300 million years!
Bizarre as it sounds, the first living (or at least recently living) coelacanth was spotted by a South African museum curator in the catch of a local angler on sale at her neighbourhood fish market. By chance she recognised it for what it was. Until that momentous day in 1938, it was believed that coelacanths, the earliest skeleton fossils of which date from about 360 million years ago in Australia, had been wiped out in the same great Cretaceous extinction event that saw off the dinosaurs.

Eighty different species of coelacanths had been identified from fossil remains discovered over a hundred year period in the 19th and 20th centuries. None had been dated more recently than 65 million years ago - so the  chance re-appearance of a living coelacanth was as shocking as if a real woolly mammoth were to come wandering in off the Siberian tundra, or a family of brachiosaurs were to be discovered alive atop an isolated Andean plateau.

Sometimes dubbed the 'fossil' fish because it is the sole remaining member of a class of animals previously known only from fossil specimens and with no close relations alive, the coelacanth is now known to have survived relatively unchanged for millions of years in the deeps of the Indian Ocean in two separate colonies, one close to Madagascar in the west, the other off Indonesia in the east.  

Coelacanths are named (you guessed it) from the Greek κοῖλος and ἄκανθα, koilos akantha meaning hollow spine, which refers to their unique paired, hollow-spined fins. They also have vestigial lungs, give birth to live young and are more closely related to tetrapods, amphibians and mammals than ray-finned fishes. It is possible that they are the last surviving example of the evolutionary stage immediately prior to our transition from sea to land.

A preserved coelacanth and 'pup'
Coelacanths are elusive, deep-sea creatures living to depths of 700 metres in a twilight zone. They are peaceful grazers of the ocean bed. They can grow up to 2 metres long and can weigh as much as 100 kilos. They propel themselves by a movement of their paired lobe fins that resembles the trotting of a quadruped. They are considered an endangered species whose population is unknown but is likely to be only a few thousand, though for all we know they have sustained themselves quite happily in those small numbers for millennia upon millennia and will continue to do so.

Very occasionally they turn up in deep-sea fishermen's catches but fortunately for them, because they don't taste very good, there is no commercial value in fishing them and they get returned to the depths - making them the ultimate throwback, if you like...

Coelacanth, coelacanth, primitive and secretive,
Obdurate oddity of ocean stream,
Extinction seemingly blinked its eye and passed you by.

Living fossil fish, maybe the missing link between
Adaptable amphibians and finny swimmers,
Consigned in perpetuity to watery twilight,
A chance resurgence rewrote your natural history.

Now that we know you're there, we'll leave you be,
Throwback whose taxonomy decrees uniqueness,
Hollow spined, happily grazing, gentle creature of the deep.

Thanks for reading. Have a good week, S ;-)


Anonymous said...

Love this blog. Funny and informative. Well done.

Anonymous said...

I read this blog a couple of times before I realised that the poem is an acrostic.

Anonymous said...

You have a very engaging style, Mr. Rowland. This was a great read. Thank you.