Gazelle : The Palestinian Biological Bulletin (ISSN 0178 – 6288) . Number 112, April 2014, pp. 1-10. | Page 3

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than to the common ray-finned fishes. They are found along the coastlines of the
Indian Ocean and Indonesia. Since there are only two species of coelacanth and
both are threatened, it is the most endangered order of animals in the world. The
West Indian Ocean coelacanth is a critically endangered species (Wikipedia,
Khalaf 2014).
Coelacanths belong to the subclass Actinistia, a group of lobed-finned fish
related to lungfish and certain extinct Devonian fish such as osteolepiforms,
porolepiforms, rhizodonts, and Panderichthys. Coelacanths were thought to have
gone extinct in the Late Cretaceous, but were rediscovered in 1938 off the coast of
South Africa. Traditionally, the coelacanth was considered a “living fossil” due
to its apparent lack of significant evolution over the past millions of years; and
the coelacanth was thought to have evolved into roughly its current form
approximately 400 million years ago. However, several recent studies have
shown that coelacanth body shapes are much more diverse than is generally
said. In addition, it was shown recently that studies concluding that a slow rate
of molecular evolution is linked to morphological conservatism in coelacanths
are biased on the prior hypothesis that these species are “living fossils”
(Wikipedia, Khalaf 2014).
"Coelacanth" is an adaptation of Modern Latin Cœlacanthus "hollow spine,"
from Greek ????-?? koilos "hollow" + ?????-? akantha "spine," referring to the
hollow caudal fin rays of the first fossil specimen described and named by Louis
Agassiz in 1836 (Wikipedia).
The coelacanths, which are related to lungfishes and tetrapods, were believed to
have been extinct since the end of the Cretaceous period. More closely related to
tetrapods than even the ray-finned fish, coelacanths were considered transitional
species between fish and tetrapods. The first Latimeria specimen was found off
the east coast of South Africa, off the Chalumna River (now Tyolomnqa) in 1938.
Museum curator Marjorie Courtenay-Latimer discovered the fish among the
catch of a local angler, Captain Hendrick Goosen, on 23 December 1938. A local
chemistry professor, J.L.B. Smith, confirmed the fish's importance with a famous
cable: "MOST IMPORTANT PRESERVE SKELETON AND GILLS = FISH
DESCRIBED" (Wikipedia).
The discovery of a species still living, when they were believed to have gone
extinct 65 million years previously, makes the coelacanth the best-known
example of a Lazarus taxon, an evolutionary line that seems to have disappeared
from the fossil record only to reappear much later. Since 1938, Latimeria
chalumnae have been found in the Comoros, Kenya, Tanzania, Mozambique,
Madagascar, and in iSimangaliso Wetland Park, KwaZulu-Natal in South Africa
(Wikipedia).
The second extant species, Latimeria menadoensis, was described from Manado,
North Sulawesi, Indonesia in 1999 by Pouyaud et al. based on a specimen
Gazelle : The Palestinian Biological Bulletin – Number 112 – April 2014