New discovery: Hand fin ever had lungs

Usually fish do not have lungs. But the finfish (cœlacanthe) surprised the scientists from the Brazilian and French research groups, when on September 15, 2015 they published in the journal Nature Communications that this deep-sea fish is still Store a remnant of respiratory organs.

Detecting sock: Hand fin with lung

This is not the first time that finfish scoff at science. During the 19th century, this 2m long fish and 100kg weight were classified as extinct species. But in 1938, a fish surrounded by prehistoric looks like 70 to 400 million years caught by a South African fisherman.

From there, it was discovered that it was still swimming in the Mozambique Strait and off the Indonesian archipelago. This 'fossilized fish' , nicknamed finfish, holds a special place in the phylogenetic chain between fish and vertebrate animals with legs. Recent findings reinforce this position of finfish.

The group of the French National Museum of Natural History and Rio de Janeiro State University (Brazil) gathered many samples of finfish to 'dissect' them with new generation photographic techniques, using a stool accelerator. death in Grenoble (France) to peel off the inner layers of the fish to the smallest details without affecting its integrity.

Hand fin fish.

In adult fish, it is found that the part of degenerated lung, which is no longer functional, is in the fat organ. This fat-filled bag allows it to adapt to buoyancy. This is a basic function performed in other fish species by fish bubbles (swordfish, river trout), fatty liver (shark) or a wax-like substance in the head (sperm whale).

In finfish, this role lies in the fat bag and therefore it easily swim in the ocean abyss with a depth of 120-800m.

The analysis of fish at the embryonic stage gives scientists a surprising information: in the smallest embryos (4cm), the lungs grow as fast as many mammal marine animals. But then the growth phase stops and the fat organ continues this process.

In fossil fossils from the Devonian to Cretaceous period (less than 410 million to less than 66 million years), it was found in its abdominal cavity a long-shaped organ filled with plaques overlap.'This organ is certainly a functional lung, which is consistent with the finfish habitats,' said the researcher, Marc Herbin.

At that time, pelagic fish did not live in the deep ocean, but on the surface water, both in sea and fresh water. It is possible that he gave up his lungs to adapt to this change.'That explains how the pompano survived the important environmental fluctuations of the Cretaceous (under 145 million to less than 66 million years) and the Paleogene period (under 65 million to under 23 million years)' - the article said.