French and South African biologists will dive to deep-sea caves in the Indian Ocean next month in a bid to locate the coelacanth, the "living fossil" fish whose history predates the dinosaurs, France's National Museum of Natural History said on Friday.
The "Gombessa" expedition, named after a local term for the coelacanth, will run from April 5 to May 15, exploring locations in the Jesser Canyon, 120 metres (390 feet) below the waters of Sodwana Bay, where the strange fish is believed to live.
A fossilised skull described last April by Chinese paleontologists dates the first coelacanths to 375 million years ago.
They were thought to have died out around 65 million years ago until one was caught off South Africa in 1938.
The grey-brown fish can grow up to two metres (6.5 feet) in length and weigh as much as 91 kilos (200 pounds).
But almost nothing is known about how it lives -- its habitat, food and reproduction.