Reef Fish Lives Fast, Dies Young, ABC.net.au, 09/08/06
By Stephen Pincock
Source: ABC Science Online
Life on the Great Barrier Reef is fast and furious for the coral reef pygmy goby, the world's shortest-living fish whose entire existence lasts no longer than two months.
The coral reef pygmy goby, Eviota sigillata, swims its way into the record books (Image: JE Randall)
The pygmy goby's record-breaking status was confirmed this week by Guinness World Records. Not only is it the fastest living fish, it has the shortest life span of any creature with a backbone known to science.
The tiny fish spend their first three weeks as larvae in the open ocean before they settle on the reef.
They then mature within two weeks and have a maximum adult lifespan of just three and a half weeks, says Professor David Bellwood from James Cook University and ARC Centre of Excellence for Coral Reef Studies.
In total, they live 59 days, "and that's the maximum", Bellwood says.
"It's like taking a 90 year old woman and saying that's how long humans live. Most of them don't make it there."
Bellwood and his colleague Martial Depczynski first reported the goby's remarkable life span in the journal Current Biology last year, and then submitted it to Guiness for world record scrutiny.
They figured out the life span of the fish by examining small bones in their ears called otoliths, which grow as they age.
"Each day, pygmy gobies lay down a new ring in their otoliths, much as a tree does for each year," Bellwood says.
The results were a complete surprise.
"We were just stunned," Bellwood says. "We thought at first it must have been a mistake, but we went back again and again and confirmed it."
Pygmy gobies (Eviota sigillata) are found on the Great Barrier Reef and other reefs in the Pacific and Indian oceans.
During their three-weeks of sexual maturity, the fish produce just three clutches of eggs. To help ensure they survive, the male goby stands guard, fanning the eggs with his fins while they are incubating.
The fast and furious lifestyle of the fish is probably an evolutionary response to the fact that they have so many predators on the reef, the scientists say.
For small species living in places where their life expectancy is low, evolution often favours a 'live fast, die young' strategy.
"It's just a case of reproduce like mad before you die," says Bellwood.