Cardiac and Locomotory Muscle Mass in Antarctic Fishes
The fish fauna around Antarctica is dominated by a single perciform suborder, the Notothenioidei, whose phylogeny has been well defined by traditional and molecular techniques. They have undergone a remarkable adaptive radiation (into a variety of forms from small, sculpin-like to large, hake-like species) that is possibly unique in the marine environment, and which molecular evidence suggests is a relatively recent event . The last few decades have seen the development of extensive scientific and commercial fishing in the Southern Ocean that has provided much data on the growth and reproduction of a wide range of species. In contrast, financial constraints and logistical difficulties have meant that studies into the physiological mechanisms that allow these fishes to successfully exploit this extremely cold and highly seasonal environment have mainly concentrated on a few species, predominantly from Nototheniidae and Channichthyidae [2,3]. Antarctic pelagic fishes are diverse in their origins, coming from bathypelagic, mesopelagic and, of most interest for our purpose, from coastal fish families that have become secondarily adapted to midwater life. However, most species (about 75% of those so far recorded) inhabit benthic or demersal niches, which is thought to reflect the benthic lifestyle of the parent taxa, and helps explain the lack of a functional swimbladder . Those species that are now able to exploit the water column have had to evolve means of adjusting buoyancy, including reduced skeletal ossification and extensive lipid deposits .
KeywordsPectoral Muscle Antarctic Fish Locomotory Muscle Pleuragramma Antarcticum Total Skeletal Muscle
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