The coelacanth is a fish often called a “living fossil” because it was thought to have vanished with the dinosaurs 66 million years ago. After its rediscovery in 1938, scientists knew of only one living species, Latimeria chalumnae, off the eastern coast of Africa. The scientific community was stunned when a second population was found thousands of miles away. The discovery of this second species, the Indonesian coelacanth, reshaped our understanding of this ancient lineage.
A Surprise Discovery in a Fish Market
The existence of an Indonesian coelacanth was revealed through a chance encounter in 1997. Marine biologist Mark Erdmann and his wife, Arnaz, were on their honeymoon in North Sulawesi, Indonesia, when they spotted an unusual fish in a local market. Erdmann recognized its distinctive, three-lobed tail and limb-like fins as a coelacanth, known to locals as “raja laut,” or “king of the sea.” The encounter sparked a dedicated search for another specimen after he managed to take a few photographs before it was sold.
Erdmann worked with local fishermen, hoping to find definitive proof of a population far from its only known habitat. Ten months later, in July 1998, a fisherman named Om Lameh Sonatham caught a second specimen. This fish survived for several hours, allowing for documentation of its coloration and fin movements while alive. The preserved specimen was sent to the Indonesian Institute of Sciences, and DNA analysis confirmed it was genetically distinct from the African population, leading to its classification as a new species: Latimeria menadoensis.
Characteristics of the Indonesian Species
The most apparent difference between the Indonesian coelacanth and its African relative is its color. While Latimeria chalumnae is a deep, cobalt blue, Latimeria menadoensis has a brownish-gray skin, which may serve as camouflage in its volcanic habitat. Both species possess fleshy, lobed fins that move in an alternating pattern, resembling how a tetrapod walks. This form of locomotion is a window into the evolutionary transition from aquatic fins to terrestrial limbs.
The Indonesian coelacanth can grow large, with some specimens reaching nearly two meters in length and weighing over 90 kilograms, although males are smaller. Its body is covered in thick, protective scales that exude oil and mucus. Internally, the fish has a hinged skull that allows it to open its mouth wide to consume large prey and a hollow, fluid-filled notochord instead of a conventional backbone. These characteristics have remained unchanged for millions of years.
Deep-Sea Habitat and Lifestyle
The Indonesian coelacanth inhabits deep waters off North Sulawesi and other parts of Indonesia, most commonly at depths between 150 and 200 meters, though sightings are recorded as deep as 700 meters. The fish resides in the ocean’s “twilight zone,” preferring the steep, rocky slopes and underwater caves formed by ancient volcanic activity. These caves provide shelter during the day, as its eyes are highly sensitive to light.
This deep-sea dweller is a nocturnal predator. After spending daylight hours in caves, it emerges at night to hunt. It employs a “drift-hunting” technique, using its fins to ride deep-ocean currents with minimal effort, ambushing prey like squid, cuttlefish, and small sharks. This energy-conserving strategy is suited to its low-metabolism lifestyle in the cold, dark depths.
Conservation Challenges
The Indonesian coelacanth is not targeted by fishermen, as its oily flesh is unpalatable and can cause illness. The primary threat is accidental bycatch from deep-set gillnets intended for sharks. Because these fish inhabit specific deep-sea caves and have a limited population, infrequent accidental catches can significantly impact their numbers. The International Union for Conservation of Nature (IUCN) lists Latimeria menadoensis as a Vulnerable species.
Following its discovery, the Indonesian government granted the species protected status. Conservation efforts focus on raising local awareness and making the coelacanth a “flagship species” for marine parks like the Bunaken National Marine Park. Protecting this fish requires a collaborative approach, emphasizing sustainable fishing practices and preserving the deep-reef ecosystems it calls home.