'Living fossil' coelacanth genome sequenced

By Rebecca Morelle, Science reporter, BBC World Service

The genetic secrets of a "living fossil" have been revealed by scientists.

Researchers sequenced the genome of the coelacanth: a deep-sea fish that closely resembles its ancestors, which lived at least 300 million years ago.

The study found that some of the animal's genes evolved very slowly, giving it its primitive appearance.

The work also shed light on how the fish was related to the first land-based animals.

The coelacanth has four large, fleshy fins, which some scientists believe could have been the predecessors of limbs.

It had been suggested that this fish was closely related to early tetrapods - the first creatures to drag themselves out of the ocean, giving rise to life on land.

But the study, published in the journal Nature, suggested that another fish called the lungfish, which also has four limbs, had more genes in common with land-based animals.

Slow to change

The coelacanth can reach up to 2m-long and is found lurking in caves deep beneath the waves.

It was thought to have been extinct for millions of years, until it turned up in a trawlerman's net off the coast of Africa in 1938.

Its ancient appearance has earned it the title "living fossil" - but it is so elusive, that it has been hard to study.

Continued:  http://www.bbc.co.uk/news/science-environment-22184556

Fish DNA Makes Limbs Sprout in Mice

Tia Ghose, LiveScience Staff Writer

Date: 17 April 2013 Time: 01:01 PM ET

The genome of a primitive fish that was once thought to have died when the dinosaurs did has now been sequenced by scientists — and when put into mice, some of the fish DNA caused mice to sprout limbs.

The new analysis, described today (April 17) in the journal Nature, could help to reveal how primitive fish swapped their fins for limbs when they moved from land to sea.

The fish, called a coelacanth, seems to carry snippets of DNA that can turn on genes that code for forelimbs and hind limbs in mice. The new discovery could shed light on how four-legged creatures, called tetrapods, evolved.

"It really is a cornerstone from which we can view tetrapod evolution," said study co-author Chris Amemiya, a geneticist at the Benaroya Research Institute in Seattle, Wash.

Living fossil

The coelacanth was once thought to have gone extinct about 70 million years ago, roughly around the time dinosaurs vanished. But in 1938, a fish trawler brought a bluish-purple, 3.3-foot-long (1 meter) fish with fleshy fins to the South African naturalist Marjorie Courtenay-Latimer. It turned out to be an African coelacanth.

Continued:  http://www.livescience.com/28797-coelacanth-genome-sequenced.html

2nd coelacanth population found off Tanzania coast (via Chad Arment)

The Yomiuri Shimbun
(Nov. 10, 2011)

A team of Japanese researchers has discovered a hitherto unknown population of coelacanths, a fish species known as a "living fossil," off southeast Africa.

The researchers from Tokyo Institute of Technology and other entities said the newly found breeding group of coelacanths linked to the site has existed for more than 200,000 years without genetic contact with other groups.

Researchers had believed there was only one breeding group of the species off Africa.

The team published the results in an online edition of the Proceedings of the National Academy of Sciences of the United States.

Coelacanths have been found only in the sea off Africa and Indonesia. In Africa, an area in the sea around the Comoros Islands near Madagascar is home to the only previously known population of the fish.

Tokyo Institute of Technology Prof. Norihiro Okada and his colleagues analyzed genes of more than 20 coelacanths caught off Tanga, northern Tanzania, and nearby sites. The areas are nearly 1,000 kilometers north-northwest of the Comoros Islands.

The results showed the fish belong to a population genetically distinct from that off Comoros Islands.

The two groups seem to have separated 200,000 to 2 million years ago, the researchers said.

Considering the number of fish caught, the researchers assume the newly discovered population may comprise hundreds of coelacanths near the site.

http://www.yomiuri.co.jp/dy/features/science/T111108004421.htm

Coelacanth slowly reveals its secrets

http://www.bbc.co.uk/blogs/wondermonkey/2011/06/slow-reveal-of-the-coelacanths.shtml

An odd-looking ancient fleshy fish continues to serve as a reminder of just how little we know about the natural world.

In 1938, scientists discovered the coelacanth, a large primitive deep-dwelling fish that was supposed to have been long, long extinct.

The fish provided an immediate link to our dim evolutionary past, resembling the lobe-fin fish that were likely the first to leave the water and take to land, ultimately begetting the amphibians, reptiles and mammals we see today, including the human race.

Read on..