A living fossil in a fish market
The story of the Indonesian coelacanth begins not in the deep ocean, but in a bustling market. On September 18, 1997, biologist Mark Erdmann and his wife Arnaz Mehta were on their honeymoon on the island of Sulawesi when she spotted a large, strange brown fish on a cart. Erdmann recognized it as a coelacanth, a type of fish known only from fossils until a first living species (Latimeria chalumnae) was found off South Africa in 1938. Coelacanths were believed to have gone extinct alongside the dinosaurs 66 million years ago. This Indonesian fish was brown with golden flecks, unlike the known blue African species. After taking a few photographs, the couple watched it being sold.
Erdmann spent the following months searching for another specimen. On July 30, 1998, a fisherman named Om Lameh Sonatham caught a second one, measuring 1.2 meters and weighing 29 kg. This specimen confirmed the existence of a second, completely isolated population over 10,000 kilometers away from its African relatives. Subsequent genetic analysis confirmed it was a new species, officially named Latimeria menadoensis in 1999. DNA analysis shows the two species have a nucleotide difference of 4.1% and may have diverged from a common ancestor between 30 and 40 million years ago.
Life in the deep volcanic slopes
Latimeria menadoensis lives in the deep volcanic underwater areas off the coast of North Sulawesi, particularly around the islands of the Bunaken National Park. Submersible and ROV surveys have spotted them in steep, rocky areas full of caves, which are their primary habitat. They occupy depths between 150 and 200 meters, though they have been observed as deep as 218 meters. The water temperature in this zone is cold, typically between 14 and 18 degrees Celsius.
The coelacanth has several unique anatomical features. It possesses an intracranial joint, a hinge in its skull that allows it to open its mouth extremely wide to consume prey. This feature, along with a powerful basicranial muscle, increases its bite force. Instead of a typical backbone, it has a flexible, oil-filled tube called a notochord. Its most distinctive features are its fleshy, lobed fins, which move in an alternating pattern, similar to the walking gait of a four-legged land animal. This has made the coelacanth a subject of study for the evolutionary transition of vertebrates from water to land.