African coelacanths are very old. Fossil evidence dates its genesis to about 400 million years ago, and scientists thought they were extinct until 1938, when the museum’s curator Marjorie Courtenay-Latimer one was spotted alive in a fishing net.
Found on the southeast coast of Africa, coelacanths they also live a long time – scientists have suspected about 50 years. But it shows that life expectancy has been hard. (Coelacanths are endangered and accustomed to deep water, so scientists can’t just put their creatures in a tank and start a stopwatch.) Now a French research team examining their scales with polarized light has determined that they could. live much, much longer. “We were amazed,” says Bruno Ernande, a marine ecologist who led the study. The estimated new life, he says, “was almost a century old.”
His team at the French Institute for the Exploitation of the Sea, or IFREMER, found not only that individuals can live up to almost 100, but also that they have gestation periods of at least five years, and cannot mature. sexually until they are at least 40. The results were published Thursday in Current biology. This slow-moving life highlights the importance of conservation efforts for this rare species, which is marked as “critically endangered” in the world. IUCN Red List. Only about 1,000 exist in the wild, and their long gestation and late maturity are bad news for their population’s resistance to contact with humans. “It’s even more dangerous than we thought before,” says Ernande.
“It will have huge consequences,” agrees Daniel Pauly, an ichthyologist at the University of British Columbia, who was not involved in the study. Pauly is the creator of FishBase, a database of biological and ecological information on tens of thousands of species. If a fish takes decades to generate, then slaughter eliminates its potential to replenish the population. “A fish that needs 50 years to reach maturity, as opposed to 10 years, is five times more likely to get in trouble,” he says.
The coelacanths are large scales that grow up to two inches long, and for decades ichthyologists have been debating how to read those scales for signs of age. In the 1970s, researchers noticed small calcified structures on them. They figured that the rings were age markers, like the rings of the tree. I disagree, however, on how to count them: Some have understood that each marking indicated a year; others believed that seasonal flips created two rings a year. At the time, the best fortune teller had placed her life expectancy at about 22 years. This conclusion, which meant that a 6-foot, 200-pound coelacanth was 17 years old, implied that they would grow very quickly: “They will grow faster as the tone, which is crazy,” says Pauly.
It’s crazy because they are animals with slow metabolisms, which should indicate slow growth. Coelacanth hemoglobin is adapted to that slow metabolism, which means they can’t take in enough oxygen to support a fast-growing fish. Some argue that their small gills are more evidence of oxygen limitations. They also live very passive lifestyles, resting most of the day in caves and gliding slowly through the twilight zone of the ocean, falling to 650 feet and below, when they deigned to move. “However, biological characteristics point to a slow-life fish,” says Ernande.
In addition, scientists who track the lives of individual celiacs have learned that 20 years is too low. In the 1980s, researchers began sending submarines and vehicles to remote operation to a cave that housed 300 to 400 celiacs. They returned to this place for more than 20 years. During each visit, they recognized individuals for their distinctive white marks. Only about three or four fish in this group die, and an equal number of nine will be born, each year. This observation has provided surprising evidence that coelacanths live a long life – even more than 100 years, this study argues.