Wednesday, June 15, 2011

Coelacanth




The flagship species of "living fossil" (slideshow here), the coelacanth (pronounced "SEEL-uh-kanth") - assumed to have died out 65 million years earlier (2nd image) - was discovered still alive in 1938. Marjorie Eileen Doris Courtenay-Latimer (1907-2004), a curator of South Africa's East London Museum, recognized the possible significance of a large fish (1st image) in the haul of a local fisherman. She describes the scene in her diary:
"Around lunchtime, Nigel rang to tell me that the Nerine had just pulled into port. My friend, Capt. Hendrick Goosen, had just returned from a trawling trip around the mouth of the nearby Chalumna River. Hendrick often calls on me when his catch is substantial so that I can look and see if there may be anything of scientific interest for the museum. More often than not, I find nothing but a pile of malodorous fish. For this reason, and because the proposition of venturing out into the midday heat and dust seemed torturous, I hesitated. Upon consideration, however, I figured that it might be the last opportunity I would have to visit with the Captain and to wish him and his crew a Merry Christmas before the 25th. I chatted idly with the amicable Captain while we circled the huge heap of fish lying on the deck of the trawler, scanning the pile for anything unusual. I was just about to leave when a strange bluish fin poking through the pile caught my eye. It was like no fish fin I had ever seen in all my years at the museum. The Captain and I shoved the other fish off the top of the pile to uncover the owner of the odd fin. There it lay before me, the most beautiful fish I had ever seen, five feet long, and a pale mauve blue with iridescent silver markings. I am no fish expert, but I had the strange feeling that somehow this fish was special. I decided to take the fish with me, and after a heated discussion with the taxi driver, we stuffed the huge fish into the backseat of the cab and headed off for the museum."
The fish was identified by South African ichthyologist J.L.B. Smith (photos here) who commented, "If I'd met a dinosaur in the street I wouldn't have been more astonished." Courtenay-Latimer's hunch was vindicated and the coelacanth (3rd image, see it swimming here) was named "Latimeria chalumnae" in her honor.

But scientists have now discovered that not only is the species ancient, the individual specimens are, too. National Geographic reported that coelacanths may live to 100 years or longer. Ethologist Hans Fricke just published the results of a 21-year study of a coelacanth population found near the Comoros Islands in the Indian Ocean. Living too deep for divers to descend, the fish were observed from submersibles. They were unable to find any young coelacanths in the population of 300-400. The 3 or 4 that died each year were not replaced by newborns, but by adults that would just mysteriously show up. What makes their study even harder is that the coelacanths age so well, and their scales don't show growth rings like other fish. Fricke said, "We photographed some adults that arrived at the colony in 1989, and they did not grow at all. You just can't look at a coelacanth and speculate about age."

One of my earliest followers, Kent Schnake, points out that fishermen in the Indian Ocean had been catching coelacanths for years before their rediscovery and tossing them back because they weren't good to eat. Kent concludes, "Apparently it is far easier to remain incognito if you taste terrible!"

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