This Once Thought 'Living Fossil' Fish Can Be Found in the Celebes Sea

Very, very few “living fossils” survive to this day. A living fossil is a surviving species that cosmetically resembles related species known only from the fossil record. The coelacanth (pronounced SEE-la-canth), a fish thought to have gone extinct along with the dinosaurs 66 million years ago, was once thought to be a living fossil. A live coelacanth was first caught in 1938 off South Africa’s eastern coast. Many years later in 1998, a separate population was discovered in the Celebes Sea. 

Coelacanths belong to a really old species of fish whose earliest fossil records date back to 400 million years ago—predating dinosaurs by 170 million years. 

In a study published in 2021, scientists were surprised when they learned that the coelacanth could be one of the earth’s longest-living animals. They don’t reach sexual maturity until 55 years, and their gestation period or the time between conception and birth takes up to a hundred years. No animal is known to have that span of gestation period, and you thought elephants’ two-year pregnancies were long. Only the Greenland shark has a longer lifespan of 400 years. 

Where do coelacanths live?

Coelacanths are found in only two major places in the world: The east African coast and the Celebes Sea in Indonesia. They live in depths reaching 800 meters or nearly one kilometer and prefer warm waters. 

Although the two places could host two closely related species of coelacanths. First described in Nature in 1939, the coelacanth is thought to inhabit only the waters of eastern Africa. But in 1998, an Indonesian fisherman surprised scientists after he found a strange fish while sailing in the Celebes Sea. 

“The discovery of a second population gives the problem a badly needed dose of perspective. The researchers think that the Indonesian coelacanths probably belong to Latimeria chalumnae, but have certain differences: the Comoro coelacanth is blue-grey in color, the Indonesian version is more of a brown shade, with golden flecks,” reads the 1998 report on Nature. 

The Celebes Sea is in the heart of the Coral Triangle, a region with the world’s highest concentration of marine biodiversity. The Philippines is part of the Coral Triangle. Of all the known marine species in the world, 70 percent are found in the Philippines. 

In 2013, a research group published a genome sequencing of the coelacanth and discovered that the fish is still evolving today. The reason why the fish hasn’t changed appearance for 400 million years is that there was no evolutionary pressure exerted on the fish. In other words, it was so comfortable with its environment that it didn’t need to evolve. “A static habitat and a lack of predation over evolutionary timescales could be contributing factors to a lower need for adaptation,” wrote the authors of the study.