Coelacanths Can Live Past 100, Don't Show Age?
Two-decade study unlocks secrets of "living fossil" fish.
Not only is the coelacanth one of the world's oldest fish species, but the individual fish may also be long-lived.
A new study suggests the ancient fish can live up to a hundred years and even longer.
Until 1938, when a coelacanth (pronounced SEE-la-kanth) was found off Africa's coast, scientists had believed the fish went extinct 65 million years ago with a related lineage of prehistoric fishes. (See more coelacanth pictures.)
After the coelacanth's rediscovery, a number of populations were uncovered in parts of the western Indian Ocean and in the western Pacific Ocean. Whether these populations were interconnected was a mystery.
"People kept catching these fish, but that didn't tell us anything about their population, how numerous they were, or if they were maybe simply strays from different parts of the ocean," said study leader Hans Fricke, an ethologist—or expert in animal behavior—formerly of the Max Planck Institute in Bremen, Germany.
(Related picture: "'Extinct' Coelacanth Hooked in Asia.")
Coelacanths Studied via Submersible
This lack of reliable data led Fricke and colleagues to begin a 21-year study of a coelacanth population found near the Comoros, a group of islands between the Seychelles and Madagascar.
Because the fish live at depths of about 525 to 650 feet (160 to 200 meters), sending divers down to observe the fish was out of the question.
Instead, the team used submersibles to photograph, videotape, and study the fish. Because coelacanths have unique white markings on their sides, the team was able to identify more than 140 individuals during hundreds of submersible trips.
But the team couldn't find any youngsters in the population of 300 to 400 coelacanths.
There's also little known about how the fish are born, noted Fricke, whose study appeared recently in the journal Marine Biology.
"We darted a pregnant female with a pinger [a type of tracking device] and followed her descent into the deep, so we think mothers may be going to great depths to give birth," he speculated.
Even stranger, only three or four coelacanths seemed to die each year, and their places in the population were taken by three or four new adults that would just mysteriously show up from nowhere.
Because roughly 4.4 percent of a given population of coelacanths appear to die each year—a figure at the lower end of observed mortality rates among fish—Fricke estimated that coelacanths have a longevity of about 103. Other fish, such as deepwater rockfishes of the genus Sebastes, have similar death rates and live for about a hundred years.
With so few deaths and so few replacements in the population, Fricke argues that the evidence is clear that these fish are very long-lived.
(See "405-Year-Old Clam Called Longest-Lived Animal.")
Youthful-Looking Fish Hard to Age
Even so, the fish don't show the ravages of time, which makes determining their age very hard.
What's more, normal methods for measuring fish ages, such as measuring growth rings on their scales, aren't possible with coelacanths. That's because coelacanth scales don't seem to change over time like other fish, Fricke said.
"We photographed some adults that arrived at the colony in 1989, and they did not grow at all. You just can't look at a coelacanth and speculate about age."
Related Topics
You May Also Like
Go Further
Animals
- What La Palma's 'lava tubes' tell us about life on other planetsWhat La Palma's 'lava tubes' tell us about life on other planets
- This fungus turns cicadas into zombies who procreate—then dieThis fungus turns cicadas into zombies who procreate—then die
- How can we protect grizzlies from their biggest threat—trains?How can we protect grizzlies from their biggest threat—trains?
- This ‘saber-toothed’ salmon wasn’t quite what we thoughtThis ‘saber-toothed’ salmon wasn’t quite what we thought
- Why this rhino-zebra friendship makes perfect senseWhy this rhino-zebra friendship makes perfect sense
Environment
- What La Palma's 'lava tubes' tell us about life on other planetsWhat La Palma's 'lava tubes' tell us about life on other planets
- How fungi form ‘fairy rings’ and inspire superstitionsHow fungi form ‘fairy rings’ and inspire superstitions
- Your favorite foods may not taste the same in the future. Here's why.Your favorite foods may not taste the same in the future. Here's why.
- Are the Great Lakes the key to solving America’s emissions conundrum?Are the Great Lakes the key to solving America’s emissions conundrum?
- The world’s historic sites face climate change. Can Petra lead the way?The world’s historic sites face climate change. Can Petra lead the way?
History & Culture
- Hawaii's Lei Day is about so much more than flowersHawaii's Lei Day is about so much more than flowers
- When treasure hunters find artifacts, who gets to keep them?When treasure hunters find artifacts, who gets to keep them?
- Meet the original members of the tortured poets departmentMeet the original members of the tortured poets department
- When America's first ladies brought séances to the White HouseWhen America's first ladies brought séances to the White House
Science
- Should you be concerned about bird flu in your milk?Should you be concerned about bird flu in your milk?
- Here's how astronomers found one of the rarest phenomenons in spaceHere's how astronomers found one of the rarest phenomenons in space
Travel
- Are Italy's 'problem bears' a danger to travellers?Are Italy's 'problem bears' a danger to travellers?
- How to navigate Nantes’ arts and culture scene
- Paid Content
How to navigate Nantes’ arts and culture scene - This striking city is home to some of Spain's most stylish hotelsThis striking city is home to some of Spain's most stylish hotels
- Photo story: a water-borne adventure into fragile AntarcticaPhoto story: a water-borne adventure into fragile Antarctica