The coelacanth is a remarkable and ancient fish, often referred to as a “living fossil.” This unique deep-sea inhabitant has captivated scientists since its rediscovery. The enduring mystery surrounding its existence and its unusual biological features contribute to the intrigue of this fascinating creature.
The Deep-Sea Environment
Coelacanths inhabit deep-water environments, typically found at depths ranging from 100 to 700 meters. During daylight hours, they often aggregate in submarine caves and crevices formed by volcanic activity or rocky reefs. These features provide shelter from predators and strong ocean currents.
The conditions in these deep-sea habitats are characterized by low light, often described as the “twilight zone” of the ocean. The water temperature remains consistently cold and stable, generally between 13°C and 22°C, with some specific habitats around 18-20°C. This consistent temperature range is considered optimal for the coelacanth’s blood to absorb oxygen. They will adjust their depth to find these specific temperature conditions.
Geographic Distribution
There are two recognized species of coelacanth. The West Indian Ocean coelacanth, Latimeria chalumnae, is primarily found around the Comoro Islands, located between Madagascar and the east coast of Africa. Smaller breeding groups of Latimeria chalumnae have also been identified along the African coast, extending from Kenya to South Africa, including off Tanzania and Mozambique.
The second species, the Indonesian coelacanth, Latimeria menadoensis, was discovered in the late 1990s. This species inhabits the waters of Eastern Indonesia, particularly around Sulawesi, including areas like Manado Tua Island, Talise Island, and Gangga Island. Sightings have also been recorded off Biak Island in Papua. These populations are largely isolated, with genetic analysis indicating the two species have been separated for millions of years.
Habitat and Survival
Deep-sea caves and rocky overhangs provide shelter for coelacanths. These sheltered spaces offer protection from predators like sharks and allow the fish to conserve energy by avoiding strong currents during the day. Coelacanths are nocturnal, emerging from resting spots to forage at night.
As “passive drift feeders,” coelacanths move slowly near the seafloor, consuming other deep-sea fish and cephalopods such as cuttlefish, squid, and octopus. Their unique rostral organ, filled with gel, aids in detecting prey through low-frequency electrical signals in the dark environment. Understanding and protecting these specific deep-sea habitats are important for coelacanth conservation, especially considering threats such as bycatch in fisheries and habitat destruction from deep-sea development activities.