Meet the Coelacanth— the Fish That Lived

Living Fossils

Fossils, as almost everybody knows, are the preserved remains of animals, plants, and even microorganisms from ancient times. Common sense tells us fossilized animals are dead; by definition they have been dead for millennia. Therefore when one hears the term “Living Fossils” it does sound like an oxymoron. However, contradictory as the name may sound, Living Fossils are very much alive. A Living Fossil is an animal or plant that was once known only by its fossils and believed toOminious have signs been extinct for millions of years. But then, one fine day, to the amazement of the world, and incredulous joy of the scientists, they were found to be still walking (or swimming or flying!) the Earth. Thus, Living Fossils are denizens of an age that has long been lost in the swirling mists of time. A Living Fossil closely resembles its fossil ancestors. Living Fossils allow us the privilege to observe first-hand a species that we had thought we had lost for ever. It is a wondrous fact that these species have survived the passage of time almost unchanged. The study of Living Fossils allows us to glimpse a world that has disappeared forever. It is history in the garb of contemporariness! The lineage of Living Fossils shows that the species have changed very little over time. Fossils over 300 million years old exist which are almost identical to the species that exists as a Living Fossil today. Some scientists think that these species inhabited relatively isolated habitats, where no major competitors existed. So, if their habitats were stable there was no pressure for them to adapt and change…and they didn’t.

Meet the Coelacanth— the Fish that Lived

Harry Potter, The-Boy-Who-Lived, has Prof. Smith recognized the fish from the competition! Not from Draco Malfoy and sketch, but he hesitated to commit himself others of his ilk, but from a fish that without examining it first hand. He knew the figuratively speaking, rubbed fins with the risk of ridicule that he ran if he announced dinosaurs. The fish that lived is called the the existence of live Coelacanths. So he Coelacanths on the postage stamp Coelacanth (pronounced See-la-kanth sent a telegram to Marjorie saying “Save (right) and meaning “hollow spine” in Greek). viscera...fish interesting.” Then he began to Scientists, having had access only to read up about the Crossopterygii – the sort fossilized specimens (more than 350 of fish the Coelacanth was. Finally he landed of the creature. He was so excited that he million years old), believed that the up at East London. Despite knowing it in began to shake. Coelacanth had died out about 65 million his heart that he was about to see a He later wrote, “Yes, there was not a years ago. contemporary Coelacanth, Smith was not shadow of a doubt, scale by scale, bone On 22 December 1938, the vessel, prepared for his own reaction at the sight by bone, fin by fin, it was a true Nerine, trawling off the mouth of the Chalumna River in South Africa returned to harbour. Marjorie Courtenay-Latimer, Curator of the East London Museum in South Africa came on board to search through the daily catch, as was her practice. That day, she spotted an oddly shaped, blue-gray fin protruding from beneath a mountain of fish and pulled out the specimen to take a closer look. The fish was about 1.5 m long, weighed 57 kg, and was covered with deep-blue scales. It had unusual fins that made it look like it had legs. Marjorie brought back the specimen to the museum where she compared it against images of known species but failed to identify it. So she dashed off a letter and a rough sketch to Prof. J.L.B. Smith at Rhodes University, South Africa. She also preserved the fish for further study. 54 SCIENCE REPORTER, January 2010 Living Fossils

Fossil of Coelacanths and coin based on the fossil (inset)

Marjorie Courtenay-Latimer (above) and her sketch (below)

later wrote a book, Old Fourlegs, The Story of the Coelacanth. The Coelacanth was given the name Latimeria chalumnae in honour of Marjorie Courtenay-Latimer who first spotted it and after the Chalumna River from where the first specimen was caught. Today we know that Coelacanths are Living Coelacanths elusive, deep-sea fish that swim at depths up to 700 meters below the surface. They can be huge, reaching 2 meters or more Coelacanth. It could have been one of and weigh up to 90 kilograms. It is thought those creatures of 200 million years ago that they have a life span of about 60 come alive again.” The announcement years. There are only two known species have been separated for at least several that a live Coelacanth had been caught of coelacanths: the Steel-blue coloured millions of years. was made on 20 February 1939. Smith ones that live off the east coast of Africa, The Coelacanth has been declared and the brown coloured ones found in the an endangered species by the international Although Latimeria menadoensis waters near Indonesia. community. Their current world population The Indonesian species was first superficially resembles Latimeria is believed to be fewer than 500 animals. reported in September 1997 by Dr. Mark chalumnae, analyses of DNA from This means that without protection, this fish Erdmann who spotted it while on his that has survived for over 350 million years tissue samples have revealed honeymoon. Dr. Erdmann returned to could be wiped out in our lifetime. Local significant genetic differences Indonesia in November 1997 in search fishermen of course, knew about of another specimen and spent the next Coelacanths much before Smith’s discovery, five months interacting with local but since it was not edible they had not fishermen who admitted that they been interested in it…a fact that perhaps occasionally caught such a fish. The local extended the Coelacanth’s lease of life. name for the Coelacanth was Raja laut (“king of the sea.”). The Coelacanth’s true evolutionary After careful monitoring of the catch relationships are still to be resolved for several months, Dr. Erdman finally laid although it has graced the covers of eyes on a second Coelacanth on 30 July science journals such as Nature and 1998. When the injured fish eventually Genome Research. Experts agree that died, it was frozen and later donated to these fish probably occupy a side branch the Indonesian Institute of Sciences. The quite low in the vertebrate lineage, closely Indonesian species is called Latimeria related to, but distinct from, the ancestor menadoensis. Although Latimeria of four-legged vertebrates. menadoensis superficially resembles Latimeria chalumnae, analyses of DNA Dr Sukanya Datta from tissue samples have revealed Scientist NISCAIR posted to Director General's significant genetic differences and it has Technical Cell, CSIR HQ been postulated that the two populations Email: [email protected] SCIENCE REPORTER, January 2010 55