Friday, April 26, 2013

Coelacanth genes mapped, "Living Fossil" evolved slowly

A coelacanth poses for its portrait in South Africa's Sodwana Bay.
Photograph by Laurent Ballesta, National Geographic

From NationalGeographic

In the deep sea, slow and steady wins the race—and that proverb is reflected in the genes of the coelacanth (Latimeria chalumnae), a new study says.

>>> geolocalization with the Marine GeoGarage <<<
Following the discovery of coelacanths in Jesser Canyon caves off Sodwana Bay, Kwazulu-Natal, in October 2000, the diver and naturalist Laurent Ballesta, accompanied by a team of deep-sea divers, is looking -120 meters below the surface- for 'gombessa' this peaceful 2 m long giant, thought to be extinct for 70 million years and rediscovered alive in 1938.

When the study authors sequenced the ancient fish's genome, they found that its genes have been evolving more slowly than the genes of the other fish or terrestrial vertebrates they looked at, including sharks, chickens, and lungfish.
(Also see "Coelacanths Can Live Past 100, Don't Show Age?")

Coelacanth is considered the greatest zoological discovery of the twentieth century:
- It has characteristics representative of the transtition of fishes to the first early land vertebrates with four legs
- It is, with its lobe-like fins and primitive lung, a living and unexpected relic of the sea some 370 million years ago.

In the paper, published April 18 in the journal Nature, the researchers speculate that the coelacanth's relatively unchanged deep-sea habitat, and an apparent lack of predation over thousands to millions of years, means this ancient fish didn't need to change much to survive.
(See more pictures of deep-sea creatures.)

"Living Fossil" Fish Revealed

Coelacanths live as deep as 2,300 feet (700 meters) below the sea surface, and can reach 6.5 feet (2 meters) in length.

Often referred to as a "living fossil," the coelacanth looks remarkably similar to its fossil relatives from 300 million years ago.
(See more pictures of this ancient-looking fish.)

 360 million year old fossil found in Australia

Scientists had thought the coelacanth (pronounced SEE-la-kanth) had gone extinct about 65 to 70 million years ago until a researcher stumbled on a freshly caught specimen off the coast of South Africa in 1938.

And since its discovery, about 300 individuals have been recorded in two areas in the world—near the Comoros Islands (map) off the eastern coast of Africa and in the waters near Sulawesi, Indonesia (map).

A second living species of coelacanth, Latimeria menadoensis, was also discovered in 1997 off the coast of Indonesia.
(Related: "New Species: 'Rebel' Coelacanth Stalked Ancient Seas.")

Links :

No comments:

Post a Comment