West Indian Ocean coelacanth

Species of lobe finned bony fish

The West Indian Ocean coelacanth (Latimeria chalumnae) (sometimes known as gombessa, African coelacanth, or simply coelacanth) is a crossopterygian, one of two extant species of coelacanth, a rare order of vertebrates more closely related to lungfish and tetrapods than to the common ray finned fishes. The other extant species is the Indonesian coelacanth (L. menadoensis). The West Indian Ocean coelacanth was historically known by fishermen around the Comoro Islands (where it is known as gombessa), Madagascar, and Mozambique in the western Indian Ocean, but first scientifically recognised from a specimen collected in South Africa in 1938. This coelacanth was once thought to be evolutionarily conservative, but discoveries have shown initial morphological diversity. It has a vivid blue pigment, and is the better known of the two extant species. The species has been assessed as critically endangered on the IUCN Red List. Similar to cartilaginous fish, Latimeria chalumnae has a rectal gland, pituitary gland, pancreas, and spinal cord. To balance osmotic pressure, these fish adopt an efficient mechanism of osmoregulation by retaining urea in their blood. Latimeria chalumnae are an ovoviviparous species, which means that they retain their eggs internally until they hatch. They also have low fecundity due to their long gestation period of around 12 months, though not much is known about their age of sexual maturity.

L. chalumnae are usually found between of depth, but are sometimes found as deep as Some of their known prey species are fish that include: Coranthus polyacanthus, Beryx splendens, Lucigadus ori and Brotula multibarbata. This behavior is made possible due to the coelacanth's ability to move both its upper and lower jaw, which is a unique trait in extant vertebrates that have bone skeletons. In 1998, the total population of the West Indian Ocean coelacanth was estimated to have been 500 or fewer, a number that would threaten the survival of the species. Near Grand Comoro, an island northwest of Madagascar, a maximum of 370 individuals reside. Correspondence in the archives of the South African Institute for Aquatic Biodiversity (SAIAB, formerly the JLB Smith Institute of Ichthyology) show that Goosen went to great lengths to avoid any damage to this fish and ordered his crew to set it aside for the East London Museum. Goosen later told how the fish was steely blue when first seen but by the time the Nerine entered East London harbour many hours later the fish had become dark grey. Failing to find a description of the creature in any of her books, Courtenay Latimer attempted to contact her friend, Professor J. L. B. Smith, but he was away for Christmas. Unable to preserve the fish, she reluctantly sent it to a taxidermist. When Smith returned, he immediately recognized it as a coelacanth, known to science only from fossils. Smith named the fish Latimeria chalumnae in honor of Marjorie Courtenay Latimer and the waters in which it was found. The two discoverers received immediate recognition, and the fish became known as a "living fossil". The 1938 coelacanth is still on display in the East London Museum. However, as the specimen had been stuffed, the gills and skeleton were not available for examination, and some doubt therefore remained as to whether it was truly the same species. Smith began a hunt for a second specimen that would take more than a decade. The West Indian Ocean coelacanth was later found to be known to fishermen of the Grande Comore and Anjouan Islands, where it inhabits the slopes of at depths between It has since been accepted as Latimeria chalumnae.

The West Indian Ocean coelacanth (Latimeria chalumnae) is allocated to the genus Latimeria, which it shares with one other species, the Indonesian coelacanth (Latimeria menadoensis).

The genome of Latimeria chalumnae was sequenced in 2013 to provide insight into tetrapod evolution.