Icefish

Icefish

The Antarctic icefish belong to the perciform suborder Notothenioidei and are the largely endemic, dominant fish taxa in the cold continental shelf waters surrounding Antarctica. At present, the suborder includes eight families with 43 genera and 122 species. Although the Southern Ocean is relatively well sampled, new species of notothenioids are still being described. The majority of notothenioids live at seawater temperatures between of –2°C and 4°C, but some subpolar species inhabit waters that may be as warm as 10°C around New Zealand and South America. Seawater temperatures below the freezing point of fresh water (0°C) are possible because dissolved salts lower the freezing point of a solution in a colligative manner. Notothenioids have a depth range of about 1500 m. The notothenioids all lack a swimbladder, and the majority of species are therefore benthic or demersal in nature. However, a depth-related diversification has given rise to some species attaining increased buoyancy, using lipid deposits in tissues and reduced ossification of bony structures. Reduced ossification of the skeleton in the notothenioids changes their weight and henceforth has created a sort of neutral balance in the water, where the notothenioid neither sinks nor floats, and can thus adjust depth easier.

Icefish

Icefish

Icefish

Icefish

Icefish

Icefish

Icefish

Icefish

Icefish