From: itannman@dogbert.ucdavis.edu (Ann Mansker)
Subject: Critter of the Week: Latimeria chalumnae 
Date: 3 Nov 1998
Newsgroups: ucd.life 


The coelacanth is the last of an ancient lineage of crossopterygians, or
lobed-finned fishes.  The fossil record for coelacanth species begins 450
million years ago and extends up to 65 to 70 million years ago; at that
point, paleontologists believed, the crossopterygians died out.  This turned
out to be an error.  60 years ago, the coelacanths emerged from their long
obscurity when a museum curator found a freshly dead coelanth among a
fisherman's catch.

Little is known about the coelacanth except through examination of the
roughly 100 specimens that have been accidentally caught by fishermen of the
Comoros Islands.  They are ovoviviparous; the eggs hatch and the young 
develop inside the mother until they are capable of fending for themselves.
The spine is cartilaginous, though the rest of the skeleton is bone.  Adult
females reach almost 6 feet, while the males are slightly smaller.  Their
fleshy fins are jointed in such a manner that the fish can swim in any
direction, including upside down.

Coelacanths live in deep water, down to about 200 meters.  The adults gather
in groups in caves during the day, emerging at night to drift along the 
sea wall and feed. Their slow metabolisms and adaptation to pressure have so
far ensured that no coelacanth to date has survived for more than a few
hours of captivity at the surface, but they have been observed remotely and
via submersible.  A few have been radio tagged.  The whereabouts and habits
of the juveniles are a complete mystery.

Until very recently, researchers thought that the Comoros population was the
last holdout of the coelacanths.  Since the population appeared to be
numbered in the low hundreds, and a half dozen or so coelacanths are caught
each year, the decline and extinction of the fish seemed inevitable.  A new
population has been discovered off the coast of Indonesia, however, which
offers some hope that there may be a larger margin of safety than was
feared.  The new population is a little different, however -- Comoros
coelacanths are dark blue with silver flecks, while the two specimens from
Indonesia are brown with gold.

http://www.dinofish.com is a site devoted to the coelanth and its 
preservation; there are a number of images, and an animation of the complex
fin motion.  The unusual fins and tail are more clearly delineated in the
drawing at http://www.nature.ca/notebooks/english/ecoela.htm.  There is a
reasonably good image at http://weber.u.washington.edu/~islander/cpics.html