Coelacanth: Living Fossil

on Friday, April 29, 2011

Discovering a species previously thought to be extinct sounds like the plot of a Steven Spielberg film however, that’s exactly what happened in 1938 with the discovery of the Coelacanth (Latimeria chalumnae). This species of fish was thought to have last lived on Earth about 65 million years ago. To the surprise of scientists around the world, a fishing vessel accidently captured an adult and it was quickly identified as the long lost Coelacanth. More recently, in 1997, a second species of Coelacanth (Latimeria menadoensis) was identified. These deep sea dwelling fish usually inhabit waters 700 meters below the ocean surface and can grow up to two meters in length and nearly 200 pounds. The fossil record has shown that nearly 90 species were present 360-90 million years ago. However, the question may be asked, what’s so important about Coelacanths?

Coelacanths have both evolutionary as well as anatomical significance. These are some of the earliest bony fishes which are also related to lungfish. Most importantly, Coelacanths are believed to be a precursor to vertebrates. It has been hypothesized that Coelacanths, lungfish, and tetrapods diverged from one another 390 million years ago.

These fish are also unique to be characterized as having a rostral organ, which is electrosensory and used to locate prey; an intracranial joint allows the Coelacanths to open their mouth very wide for prey; a notochord that is hollow and fluid filled; as well as paired lobed fins which move in a tetrapod – like pattern. When observing the fish swimming its fins mimic the pattern of a galloping horse.

I was drawn to this topic following the Assessment Test required for this class. I encountered some difficulty answering questions regarding evolution. In an attempt to improve my knowledge on this content, I came across a National Geographic article about the Coelacanth. I was instantly drawn to this because; although I was familiar with this animal I did not know of its significant role in evolution of tetrapods.


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