From: Ann Mansker 
Subject: Critter of the Week:  Chaenocephalus aceratus
Date: 7 Sep 1998 17:00:02 GMT
Newsgroups: ucd.life

The white crocodile fish (Chaenocephalus aceratus) is one of 16 species in
11 genera of the family Channichthyidae.  They are collectively known as
icefish, and are found only in Antarctic waters.  The name applied by
whalers in the 19th centuy comes from the large, toothy mouth and the fish's
pallid appearance.

In order to live in temperatures near the freezing point of seawater
(-1.8 C), fish must have drastic adaptations.  The ice fish cope in two
ways.  Their blood contains natural antifreeze made up of glycopeptides.
This allows them to encounter ice crystals in the water without harm.  In
addition, the fish have neither hemoglobin in their bloon nor myoglobin in
their muscles.  Hemoglobin loses much of its oxygen-carrying capacity in
deep cold; though the icefish's blood  has only 10% of the oxygen capacity
at 0 C that a normal fish's does at 20 C, the normal fish would not benefit
much from its hemoglobin at 0 C.  The icefish compensates by having large
veins, a large heart and very thin blood.  The lack of hemoglobin gives the
icefish its ghostly look.

A top view of Chaenocephalus aceratus is available at
http://octopus.gma.org/onlocation/Antarctica/fullsize/fish.jpg