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Antarctic acanthomorphs peculiarities

 image: G. Lecointre
caught in a net in Antarctica
Our studies on antarctic acanthomorphs are both integrated in a scientific framework - the search for the interrelationships between species and the understanding of their biology - and an historical one: the works of our predecessors in the MNHN. In 1961, Jean-Claude Hureau, researcher at the MNHN at that time, led the first studies  on these groups. He sampled, made species lists, and gathered observations on these species, in both winter and summer, at the Dumont d’Urville station (Terre Adélie). 30 years later, these initial studies are still pursued now  by teams at the MNHN in collaboration with those of the IPEV.

Antarctic acanthomorphs belong to only 21 of of the more than three hundred acanthomorph families. Two groups actually represent the majority of species found in the Southern Ocean: the liparids and the eight families belonging to the sub-order Notothenioidei.

Neopagetopsis ionah
Neopagetopsis ionah, Channichthyidae.
 Cygnodraco mawsoni
Cygnodraco mawsoni, Bathydraconidae.
Trematomus pennellii
Trematomus pennellii, Nototheniidae.
Paraliparis antarcticus
Paraliparis antarcticus, Liparidae.
 Bovichtus diacanthus
Bovichtus diacanthus, Bovichthyidae.
(Photographs: S. Iglesias and C. Ozouf.)

Liparids (snail fishes) mostly live in deep waters, and these species are less exposed to freezing temperatures. However, some species do possess antifreeze proteins. Five of the eight notothenioid families can live in the coldest antarctic waters: nototheniids, harpagiferids, channichthyids, bathydraconids and artedidraconids (update: the classification of the group has been changed). These very cold waters often have a temperature below 0°C, however they freeze only below – 1,86°C because of their salt content. Teleost fishes are at the same temperature as their environment, and have less salt in their internal liquids than what is present in sea water. Their internal liquids would freeze, but notothenioids produce an antifreeze protein that then circulates in their blood. This antifreeze protein is a shared character of the group, inherited it from a common ancestor.

For more specific information: see Lecointre and Ozouf-Costaz (2004 [1]).

References

  1. Lecointre G, Ozouf-Costaz C.  2004.  Les poissons antigel de l'océan Austral. Pour la Science. 320:48-54.