Jump Sayings For Track

The fish fauna of regione antartica è limitata a sole 274 specie, 49 famiglie. Nonostante che l’oceano meridionale rappresenti il 10% dell’oceano della terra, questa regione ospita solo l’1% della fauna ittica del mondo che è costituita da 25000 specie.

La fauna antartica è dominata da tre discendenze: Lipariti (snailfishes – “pesci soffici”), Zoarcidi (eelpouts, “pesci labbrone”), sia bentonici che di grandi profondità, e Nototenioidi.

Nototenioidi

are 35% of the species in the waters under the ice and occupy 46% of the fund that is the habitat of the water column. This exceptional saturation of biomass from a single group is attributable to the fact that occupy niches usually occupied by different groups in temperate waters. The Antarctic environment is characterized by low temperatures, high seasonal variations, food shortages, especially during the dark winter months.

These conditions require special adaptations to freezing, the need to accumulate energy reserves during the summer months, strategies for "saving" (behaviors stand still and wait), low metabolism and seasonal reproductive cycles ....

Two questions: When you started this evolutionary success and why this group?

The isolation of Antarctica from other continents has led to a general cooling water from 16 ° of the late Eocene, with ups and downs, but with a trend line has reached the 4-5 ° of the late Miocene , then to fall sharply polar current values \u200b\u200b(around -2 ° C).

The extinction of an entire fauna is associated to both the fall in temperature is habitat loss due to this extensive glaciation.

According to the theory of evolution the ancestors of these fish had to have some genetic trait more conducive to adjustment and it seems that this feature can be traced in the evolution of these fish hemoglobin.

Their ability to use oxygen is very special.

They have only 10% of the plasma, which normally has a red-blooded fish, and this adaptation is favorable because it reduces the liquid inside the body, in a cold water that is more oxygen for its low temperature. However, these fish are able to synthesize, in their evolution, some proteins that function as antifreeze.