A fish swims in the deep ocean called the coelacanth with odd lobe-shaped fins that grows to extremely large proportions. Coelacanths can reach lengths of up to six feet and weigh about 200 pounds, making them about the size of a human male. Researchers have recently discovered that coelacanths can live for up to five times longer than previously expected.
The oldest specimen researchers have discovered was 84 years old. The team also discovered that coelacanths live life extremely slowly in many ways, including not reaching maturity until around the age of 55. The sea creature also gestates its offspring for five years. Researchers conducting the new study say the most important finding is that the coelacanth’s age had been underestimated by a factor of five.
Researchers reevaluated body growth for the creature with the new age date and found it is one of the slowest growing among fish of similar size. Scientists also looked at other life history traits showing that coelacanth’s life history is one of the slowest of all fish. Previously, the age of coelacanths was estimated by observing growth rings on their scales (seen in the photo above). Counting the growth rings led to the understanding that the fish didn’t live more than 20 years, which would make the creatures one of the fastest-growing fish, given their large size.
That quick growth didn’t mesh with the other known biological and ecological features of the fish, including a slow metabolism and low fecundity. It’s also more typical for fish that live in deep water to grow slowly and have slow life histories. In the study, researchers investigated 27 specimens that are part of the French National Museum of National History, which holds one of the largest collections of coelacanth specimens.
Previous studies relied on visibly calcified structures called micro-circuli to age the fish in a manner similar to counting growth rings on a tree. The new approach pioneered by the research team allows them to pick up on much smaller and almost imperceptible circuli on their scales. The findings suggest the coelacanths specimens are about five times older than previously believed.