The coelacanth was thought to have become extinct during the Cretaceous-Palaeogene event that wiped out the dinosaurs 65 million years ago. However, in 1938 one turned up in a fishing net in South Africa. Its genome was sequenced in 2013 and scientists hope that it could offer clues about the evolution of modern animals.
The coelacanth is actually more closely related to humans and other mammals than to ray-finned fish like tuna or trout. It measures up to 1.8 metres (5.9 feet) long and four of its eight fins are fleshy, resembling the limbs of terrestrial animals. It is one of the closest living relatives to the first four-limbed vertebrates (tetrapods) to crawl out of the sea, and its genetic information might help us to better understand what early land animals were like.
The coelacanth is fascinating because its genes are evolving more slowly than most other animals. Due to its stable environment in deep-sea caves, the coelacanth has had little need to change; the depths of the ocean have remained largely the same since prehistory. It is described as a ‘living fossil’ and closely resembles its 300-million-year-old ancestors, offering us a rare opportunity to look back in time.