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?")
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.)
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.")