April 25, 2005— "Live fast, die young" holds true for the coral-reef pygmy goby Eviota sigillata, which has just been identified as the shortest-living vertebrate.

With a maximum lifespan of 59 days, the tiny goby won the dubious title over an African fish called Nothobranchius furzeri that dies of old age after two and one half months of life.

From birth to death, the new record holder lives a frantic existence in order to keep its species from going extinct. One reason is that the fish are tempting treats for predators.

"These pygmy gobies are tiny (about a half-inch long) and so just about anything larger and carnivorous will take them," said lead researcher Martial Depczynski of the Center for Coral Reef Biodiversity at James Cook University in Queensland, Australia. "Predators might include dotty backs, cods, lizardfish, coral trout, moray eels, cardinalfishes, probably all take them. I call them the fun size 'Mars bars' of the reef. Little protein snacks!"

Depczynski and colleague David Bellwood found an unusual way to measure the fast-living fish.

They collected 319 specimens at Lizard Island on the Great Barrier Reef in Australia. For each specimen, they recorded the number of concentric mineral rings that appeared on their otoliths, or ear stones. Like growth rings on a tree, these markings delineate the passage of time and imprint events related to aging.

The findings are published in the latest Current Biology.

They later tagged 146 small reef fishes from a range of species to compare data.

The researchers found that female coral reef pygmy gobies lay three clutches of eggs for a total of around 400 eggs.

Before the eggs hatch, the male frantically fans the eggs to provide them with extra oxygen. He also makes a brave, yet often unsuccessful, attempt to guard the eggs from noshers.

Once hatched, the baby fish are larvae that remain in the larval state in the open ocean for three weeks, which is around half of their maximum lifespan. During this period, only 25 percent or so escape being picked off as snacks.

Survivors locate and settle upon a coral reef, where they grow, hurry to mate, and the whole cycle starts all over again.

"The evolution of this particular species may seem bizarre, but it really seems to work," Depczynski told Discovery News. "They are terrifically abundant on the coral reefs where I do my work, in fact ranking number one for small cryptic species at Lizard Island."

Such a chased-after meal would appear to be timid, but the coral pygmy gobies themselves are predators that feed on mini crustaceans they find on the floor of the reef. They also eat dead organic reef matter.

The gobies do not age as humans do.

"I doubt they ever get to 'old age' and 'retirement' in any human sense," Depczynski explained.

"For example, they are still reproductively capable and active at 59 days. In the absence of predation they would age like any vertebrate animal, although science still doesn't yet fully know why vertebrates (including humans) actually age, despite there being many tractable and realistic theories from spontaneous mutations in cells, damage from free radicals, weakened defense systems, to simple wear and tear."

He added, "Perhaps the pygmy goby may someday play a part in uncovering this mystery of how and why we age."

The previous shortest-lived vertebrate also may be studied to reveal more about aging, as suggested by neuroscientist Alessandro Cellerino of the Italian National Research Council's Institute of Neuroscience and Stefano Valdesalici of the Italian Killifish Association.

Two years ago, Cellerino and Valdesalici discovered that the small, green-hued Nothobranchius furzeri's life expectancy is limited by climate patterns.

"To survive the dry season, fishes of the genus Nothobranchius lay eggs that remain encased in the bottom mud until the next seasonal rains," they wrote in a Biology Letters paper.

"We found that these small fishes, even when reared in the laboratory, complete their life cycle in two months and a half and then die due to senescence."

Since old age does not account for the goby's demise, Depczynski and Bellwood think the coral reefs might hold the answers.

Depczynski said the reefs support a huge diversity of vertebrate species, with over 4,000 alone in the Indo-Pacific. The reefs are home to other life extremes, such as the smallest and earliest-maturing vertebrates, perhaps because the reefs can provide relatively stable temperatures and habitats over long periods.

Depczynski suggested that the coral reefs could yield more fishy extremes in future.

He said, "I'd like to drive home that we really know very little about the life histories, life cycles, and life styles of coral reef fishes, and that the potential of these to uncover more surprises in biology and evolution are very high."