A fish out of time
On December 22, 1938, a museum curator named Marjorie Courtenay-Latimer inspected the catch of a local fishing trawler off the coast of East London, South Africa. Among the sharks and rays, she found a five-foot-long, pale blue fish covered in hard scales with four limb-like fins. Unsure of its identity, she sketched the specimen and sent the drawing to ichthyologist J.L.B. Smith. He immediately recognized it as a coelacanth, a type of fish believed to have gone extinct with the dinosaurs around 66 million years ago. He named it Latimeria chalumnae in her honor.
The scientific world was electrified. For 14 years, this single specimen was the only proof of the coelacanth's existence until a second was caught in 1952, this time in the Comoros archipelago, which includes Mayotte. This discovery confirmed that a living population of these ancient fish persisted in the Western Indian Ocean. Genetic analysis reveals that the two known living coelacanth species, L. chalumnae in the Indian Ocean and L. menadoensis in Indonesia, may have diverged from each other between 30 and 40 million years ago.
The deep dwellers of Mayotte
The waters around Mayotte and the other Comoro Islands have the largest known population of coelacanths, estimated at 300-500 individuals. They inhabit a very specific environment: steep, rocky volcanic slopes and underwater caves. During the day, they shelter in these caves at depths between 150 and 250 meters, but at night they can descend as deep as 700 meters to hunt.
These fish have a set of primitive and specialized traits. They can grow up to 2 meters long and weigh 90 kilograms. Their bodies are a deep blue-grey, covered with unique white spot patterns that allow researchers to identify individual fish. Instead of a typical vertebral column, they have a flexible, oil-filled tube called a notochord. A hinged intracranial joint in their skull lets them open their mouths extremely wide to consume prey. Their snout contains a rostral organ, a jelly-filled cavity that functions as an electroreceptor to detect the weak electrical fields of prey in the dark.
Coelacanths have an exceptionally slow life cycle. New studies on their scales suggest they can live for 100 years. Females do not reach sexual maturity until their late 50s, while males mature between 40 and 69 years of age. They are ovoviviparous, meaning the female carries eggs internally, giving birth to live young after a gestation period of as long as five years—the longest of any known vertebrate. This slow reproductive rate makes the species, listed as Critically Endangered by the IUCN, vulnerable to threats like accidental bycatch from deep-sea fishing.