Coelacanth

Coelacanths (/ˈsiːləkænθ/ ^ⓘ SEE-lə-kanth) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods (the terrestrial vertebrates including living amphibians, reptiles, birds and mammals) than to ray-finned fish.

The name coelacanth originates from the Permian genus Coelacanthus, which was the first scientifically named genus of coelacanths (in 1839), becoming the type genus of Coelacanthiformes as other species were discovered and named. Well-represented in freshwater and marine deposits from as early as the Devonian period (more than 410 million years ago), they were thought to have become extinct in the Late Cretaceous, around 66 million years ago.

The first living species, Latimeria chalumnae, the West Indian Ocean coelacanth, was described from specimens fished off the coast of South Africa from 1938 onward; they are now also known to inhabit the seas around the Comoro Islands off the east coast of Africa. The second species, Latimeria menadoensis, the Indonesian coelacanth, was discovered in the late 1990s, which inhabits the seas of Eastern Indonesia, from Manado to Papua.

The coelacanth (more accurately, the extant genus Latimeria) is often considered an example of a "living fossil" in popular science because it was considered the sole remaining member of a taxon otherwise known only from fossils (a biological relict),^: 1 evolving a bodyplan similar to its current form approximately 400 million years ago. However, studies of fossil coelacanths have shown that coelacanth body shapes (and their niches) were much more diverse than what was previously thought, and often differed significantly from Latimeria.