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Topic Last Updated on 05-07-2024
OLD FOURLEGS
Post on topic: Coelacanth.
On December 22, 1938, floating off the South African coast in the Indian Ocean, fishermen from the Irvin & Jones Company caught an unknown creature. It weighed 188.5 lbs, was about 5 ft in length, dark blue in color, and unabashedly chomped its jaws. This was not just any fish — it had scales, fins, and…limbs. Or, more precisely, rudiments thereof. Moreover, there were seven of them: two on the back, three on the belly, and another pair on the head.
It should be noted that the local population occasionally caught these creatures and had even come up with a name for them, gombessa, which can be translated as “bitter fish.” The residents knew that it was nearly inedible (it was consumed due to the belief that its meat helped to cope with malaria symptoms), although it was possible to make something like sandpaper from their extremely strong and bristly scales. So for the local fishermen, perhaps, it was not such a curiosity; nevertheless, they called the curator of the local East London Museum, Marjorie Courtenay-Latimer. The museum had a standing arrangement with the fishermen, requesting that they report all unusual findings.
* Photo: The South African Institute for Aquatic Biodiversity
Coelacanth | Discovery of a Unique Creature
Ms. Courtenay-Latimer was an ordinary museum worker, but after a single glance at the creature, she immediately realized that there was something unique in front of her. The animal was like a bridge between a fish and a lizard. She looked through the records and could not find anything similar. Meanwhile, she needed to work quickly — the fish was decomposing in the African heat right in front of her.
Ms. Courtenay-Latimer had a hard time persuading a local taxi driver to take the decaying carcass to the museum or to even let her drag it into the car. And then, she had to listen to Dr. Bruce Beis, the Chairman of the museum, mocking her: “To you, all ugly ducklings seem to be swans.”
Nevertheless, she sent the fish to a taxidermist, sketched an approximate picture of the find, and sent for her friend, ichthyologist J. L. B. Smith, who was in a different city at the time.
Smith, who later wrote a book about the fish they discovered, called Old Fourlegs: The Story of the Coelacanth, described his feelings upon reading the letter from Ms. Courtenay-Latimer: ‘’And then a bomb seemed to burst in my brain, and beyond that sketch and the paper of the letter, I was looking at a series of fishy creatures that flashed up as on a screen, fishes no longer here, fishes that lived in dim past ages gone, and of which only fragmentary remains in rocks are known. I told myself sternly not to be a fool, but there was something about the sketch that seized on my imagination and told me that this was something far beyond the usual run of fishes in our seas...”
But that “burst” happened not only in Smith’s brain. At that time, the entire scientific world waited with bated breath. It turned out that the scientists had something more extraordinary on their hands than a dinosaur — it was a living ancestor, believed to have died out about 70 million years ago. In honor of Marjorie Courtenay-Latimer, Smith named the fish Latimeria.
Previously, species of Latimeria were called brushfishes, but this term has since become obsolete. A specimen discovered in South Africa was named Latimeria chalumnae, and in 1997–1999, a second species (which was brown in colour), Latimeria menadoensis, was discovered and described near the island of Sulawesi in Indonesia. All other species of Coelacanthiformes are now thought to be extinct.
Coelacanth | Our Cousin’s Grandpa
This fish is, of course, not our direct ancestor. Terrestrial vertebrates (also called tetrapods), to which we belong, are closer to the lungfish, an ancient group of fish possessing both lungs and gills. Nevertheless, both the coelacanth and the lungfish come from the same ancestor, and both belong to the same class of lobe-finned fish. Therefore, the “zoological sensation of the 20th century” (as Latimeria was christened) can be considered our distant relative.
Since the birth of the lobe-finned fish 400 million years ago, it has changed, albeit not too dramatically: its size has increased, its swim bladder is filled not with air but with fat, and the proportions of its body have been modified. Nonetheless, Latimeria resembles our distant forefathers. It does not have a spine but instead something like a chord, a flexible elastic rod running along its back, which was the predecessor of our bodies. Also, it has a small appendage at the end of its body, similar to the embryo of the tails seen in amphibians. But most importantly, the coelacanth has the rudiments of limbs, the very ones that helped our ancestors to climb out from the sea onto dry land.
Sarcopterygii, or lobe-finned fish, are a class of bonefish, the first category of which is the order of Coelacanthiformes. The second, Rhipidistia, is of lungfish. Most lobe-finned fish possess well-developed, fleshy blades in their paired fins.
Transition from Fish to Land Dwellers
In addition to the class of lobe-finned fish, there is the famous Tiktaalik, a more “advanced” species than Latimeria, which lived 375 million years ago and was a transitional form between fish and amphibians. It, too, was probably not our direct ancestor. Around 385–375 million years ago, many “fleshy-footed” beings began to find themselves on land, just like Tiktaalik. There were many reasons for this: from the large number of arthropods who floated along the banks of rivers and lakes, to the increasing threat of predators, to the eutrophication of small bodies of water — in those distant times, there were not enough decomposers, like fungi and bacteria, to process dead vegetation and animals, meaning that they died in the water and stayed there for a very long time, making the space very cramped.
Deeper and Colder
The coelacanth is a tropical fish, but that does not mean that it loves sunlight and heat. On the contrary, this fish prefers the depths (from 650 to 2,300 ft) and surfaces to a level of 250-330 ft only at night.
Coelacanths are predators (again, look at those teeth!). Their diet includes fish and even small sharks. Most of the coelacanth’s meals live in underwater crevices and caves, where the fish prefers to swim. The animal’s mouth structure allows it to move not only the lower jaw but also the upper one, enabling it to efficiently suck in food.
