[ASC-media] Media release: fish that live fast, die young
jca.media at starclass.com.au
Wed Sep 6 23:56:06 CEST 2006
Australian Research Council Centre of Excellence for Coral Reef Studies
September 7, 2006 - for Immediate Release
FISH THAT LIVE FAST, DIE YOUNG
Australia has just notched up a new world record - for the fastest-living fish on the planet.
The Australian coral reef pygmy goby (Eviota sigillata), which frequents the Great Barrier Reef as well as others in the Pacific and Indian oceans, enjoys barely three weeks' adult life before it meets its maker.
Researchers at the ARC Centre of Excellence for Coral Reef Studies and James Cook University (CoECRS) have received official notification from Guiness World Records Ltd that the little fish officially has the shortest lifespan of any creature with a backbone known to science.
"In total it lives for a maximum of 59 days," explains CoECRS Professor Dave Bellwood.
"Coral reef pygmy gobies spend their first three weeks as larvae in the open ocean before undergoing metamorphosis and returning to settle on the reef, where they mature within 1-2 weeks and have a maximum adult lifespan of just three and a half weeks."
Prof. Bellwood and colleague Martial Depczynski announced their discovery in a recent issue of the journal Current Biology, and have just received a certificate from Guinness World Records confirming the goby has the shortest life of any vertebrate.
"The rapid transition from larvae to settlement and then maturity is recorded in the earstones' (otoliths) of fishes by the deposition of periodic concentric rings," Prof Bellwood explains. "These provide not only a sensitive record of time but
also imprint the age at which important events take place. Each day, pygmy gobies lay down a new ring in their otoliths, much as a tree does for each year."
After settling on the reef the gobies take ten days to reach sexual maturity, leaving them barely three weeks of life left in which to enjoy it. The females produce just three clutches of eggs, totaling about 400, in a lifetime.
"Extremely short lifespans are of scientific interest because they mark current evolutionary boundaries and biological limits within which life's essential tasks must be successfully accomplished," Professor Bellwood explains.
However the pygmy goby is not merely a curiosity of nature. In a separate scientific publication, Prof Bellwood and colleagues describe how its rapid generational turnover can be used to monitor the state of recovery of reefs after they have been hit by coral bleaching, which is thought to be caused by global warming.
Despite their limited opportunity for reproduction the coral gobies are one of the most successful of reef fishes, having diversified into no fewer than 70 species spread across reefs in the Pacific and Indian Oceans.
With such a small number of eggs, the survival of the fry is of paramount importance, and the male goby stands guard, fanning the eggs with his fins while they are incubating.
With this strategy, the gobies can produce a new generation every 49 days - or up to 7.4 generations a year.
"For small species living in ecological settings where high mortality rates exist, evolution often favors a 'live fast, die young' stratagem where rapid growth and maturation are favored, as compensation for reduced life expectancy," he says.
The previous record-holder for the shortest life was a killifish which lives in seasonal rain pools in equatorial Africa and must complete its reproductive cycle before the pools evaporate.
"Coral reefs have the richest array of vertebrates of any ecosystem on the planet," Prof. Bellwood says. "More than 4000 species have been logged so far and reveal many of the extremes in biology and evolution."
"To complete all the necessary life tasks within a mere eight weeks is a considerable evolutionary achievement for a vertebrate. By accelerating life's key events, the goby is a living example of the extreme adaptability of the vertebrate life cycle.
"It also highlights the potential for coral reef ecosystems to reveal further marvels in biology."
Prof. David Bellwood, CoECRS and James Cook U, 07 4781 4447
Email: David.Bellwood at jcu.edu.au
Jim O'Brien, James Cook University Media Office, 07 4781 4822
Jenny Lappin, CoECRS, 07 4781 4222
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