Small predatory fish tank

A science team in Australia has the first clear evidence that damsel fish can change the size of both a false eye and their real eye to maximize chances of survival.

Small prey fish can grow a bigger false eye on their rear fins as a way of distracting predators and dramatically boosting their chances of survival, new scientific research has found.

Researchers from Australia’s ARC Centre of Excellence for Coral Reef Studies (CoECRS) have made a world-first discovery that, when constantly threatened with being eaten, small damsel fish not only grow a larger false ‘eye spot’ near their tail – but also reduce the size of their real eyes.

tiny-fish-eyes

The result is a fish that looks like it is heading in the opposite direction – potentially confusing predatory fish with plans to gobble them up, says Oona Lönnstedt, a graduate student at CoECRS and James Cook University.

For decades scientists have debated whether false eyespots, or dark circular marks on less vulnerable regions of the bodies of prey animals, played an important role in protecting them from predators – or were simply a fortuitous evolutionary accident.

The CoECRS team has found the first clear evidence that fish can change the size of both the misleading spot and their real eye to maximize their chances of survival when under threat.

“It’s an amazing feat of cunning for a tiny fish, ” Ms Lonnstedt says. “Young damsel fish are pale yellow in colour and have this distinctive black circular ‘eye’ marking towards their tail, which fades as they mature. We figured it must serve an important purpose when they are young.”

“We found that when young damsel fish were placed in a specially built tank where they could see and smell predatory fish without being attacked, they automatically began to grow a bigger eye spot, and their real eye became relatively smaller, compared with damsels exposed only to herbivorous fish, or isolated ones.

“We believe this is the first study to document predator-induced changes in the size of eyes and eye-spots in prey animals.”


Warm water ocean fish becoming toxic

2010-04-13 09:09:57 by generalhospital

Fish Tale
NY Times By LISA SANDERS, M.D. Published: April 5, 2010
“…Ciguatera poisoning comes from eating fish that has been contaminated with a toxin produced by an organism that grows on reef algae in some infested tropical waters. Because the toxin is stored in fat, it’s concentration increases as it moves up the food chain from the little fish who eat the tainted algae to the larger, predatory fish, like shark, snapper, grouper and barracuda, and from there to the human consumer. Unlike most other causes of food poisoning, this toxin is colorless and odorless and isn’t destroyed by cooking


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