Many species of Coelacanth, a primitive fish, are present in the fossil record, but they were thought to have gone extinct with the dinosaurs 65 million years ago. Then, in 1938, a museum curator on a South African fishing trawler caught a living species: Latimeria chalumnae. Decades later, in 1998, a second species, L. menadoensis, was photographed in an Indonesian market.
The most striking feature of this “living fossil” is its paired lobe fins that extend sideways from its body like legs and move in an alternating pattern, like a trotting horse.
L. chalumnae can live for up to 60 years and grow to be 6 feet long. It lives in deep waters, spending the day hiding in caves and feeding on fish at night. We don’t know much about the global population, but it is considered endangered. Coelacanths are at high risk of extinction when faced with threats because they are slow-growing, late to mature and long-lived
The Coelacanth maintains many of the characteristics seen in primitive fish. Unusually, it has an oil-filled tube for a backbone, something which in most vertebrates is replaced by the vertebral column early in embryonic development. It has thick scales common only to extinct fish, and an electrosensory rostral organ in its snout likely used to detect prey.
The coelacanth braincase is 98.5% filled with fat; only 1.5% of the braincase contains brain tissue! It gives birth to live young after a year’s gestation period.
Where coelacanths fit into the story of evolution of land animals is still not clear, but is an issue that continues to fascinate scientists. Analysis of the coelacanth genome is being used to study evolution of vertebrate genes and genomes.