Coelacanths were thought to have been extinct for the last 65 million years, until 1938 when a fisherman found one entangled in his net off the coast of South Africa. 1n 1997, a second species of coelacanth was found in a fish market in Indonesia, though their flesh is not good to eat as it is full of urea and very oily. Their scales also produce mucus, not a very appetising sight!

Coelacanths grow to be as much as 2 metres long and can weigh up to 80 kg. They have four fleshy fins which extend away from its body like limbs, and move in an alternating motion, with alternate pairs of fins moving together in a way that is similar to the movement of four-legged creatures on land. Coelacanths are thought to occupy a side branch of the vertebrate lineage, closely related to, yet distinct from, the ancestor of tetrapods (four-legged, land-living animals).

Another interesting fact is that the coelacanth has a hinge in its skull that allows its jaw to open incredibly wide for consuming large prey. They live in deep water of more than 100 metres (which partly explains why they “disappeared” for so long!), spending most of their days resting under rocky ledges. They are relatively “social”, found with others during the day. At night, they will travel as much as seven kilometres from their resting places to hunt for food. Their fantastically reflective disk in their eyes helps them to detect tiny amounts of light in the gloom of the deep ocean.

They don’t have a backbone, but a “notochord” – a hollow, oil-filled, pressurised tube. In most other vertebrates, the notochord is replaced by the vertebral column as the embryo develops. Their brains are really tiny, taking up just 1.5% of their cranial cavity. The rest is filled with an oily substance. Coelacanths give birth to live young after a gestation period of up to three years!

This article is an excerpt from Scuba Diver‘s “Lost Worlds”. To read more, purchase a copy of this latest issue or subscribe here at our online shop.

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