Animals and nature

The coelacanth

Fossils stop at 66 million years ago, yet a living coelacanth was hauled up off South Africa in 1938 and a second species turned up in 1997.

20 facts

At a glance

66 million years

Age of the youngest known fossil coelacanth

1938

Year a living coelacanth was identified

2 metres

Greatest length of the living West Indian Ocean coelacanth

1997

Year a second species was found in Indonesia

300 to 400 fish

Estimated Grande Comore population in a 2011 study

Coelacanths were first described by Louis Agassiz in 1836, from a fossilised fish tail that is 260 million years old.
Fossil coelacanths range in age from 409 to 66 million years old.
Because the youngest known fossil was 66 million years old, the group was assumed to have gone extinct. Scientists thought it had died out more than 65 million years ago.

On 22 December 1938, Marjorie Courtenay-Latimer, curator of the East London Museum in South Africa, noticed an unusual fish in a trawl catch.
The fish was about 1.5 metres long. Courtenay-Latimer later described it as five feet long.
JLB Smith, a fish expert at Rhodes University, saw the specimen the following February and named it Latimeria chalumnae, after Courtenay-Latimer and the Chalumna River mouth where it was caught.
A second living coelacanth was caught in 1952 by Ahmadi Abdulla, a fisherman in the Comoro Islands, about 2,000 km from the first.

The coelacanth is a lobe-finned fish with fleshy, limb-like fins, and its paired fins move in a coordinated, diagonal pattern.
It has a notochord rather than a robust spine, and a skull with a joint that lets the mouth open especially wide.
A rostral organ in the head is thought to detect the weak electrical impulses of prey. Coelacanths have been filmed holding headstands.
The living West Indian Ocean coelacanth grows up to 2 metres long, and it is usually found 90 to 300 metres below the surface in water at 18 °C or colder.
In 1975, scientists found that coelacanths give birth to live young. Pups are about 30 cm long, after a gestation of more than a year.
Litters range from 5 to 26 young.
Observations of the same individuals show a lifespan of at least 22 years, and one suggestion is that they live about 100 years.

In 1997, Arnaz Mehta Erdmann and Mark Erdmann spotted a coelacanth at an outdoor market on the Indonesian island of Sulawesi.
DNA analysis showed it was a different species, later named Latimeria menadoensis.
The Sulawesi coelacanth is listed as vulnerable by the IUCN, while the West Indian Ocean coelacanth is listed as critically endangered.
A 2011 study estimated the Grande Comore population at 300 to 400 individuals.
The coelacanth genome was sequenced in 2013.
The total population of the West Indian Ocean species is believed to be in the hundreds and declining.