A new study explains how tiny damsel fish managed to survive the wild by using false eyespots in which it shrinks its real eyes and grow bigger fake eyes to distract its predators.
Researchers from Australia's ARC Centre of Excellence for Coral Reef Studies (CoECRS) and James Cook University, headed by Oona Lönnstedt believe that their study is the first to provide evidence that fish do change the size of its real eyes and use "false eyespots" when faced under threat.
Scientists have long wondered on the purpose of the eyespots in the fish. They were wondering if these eyespots can be used as protection or just an evolution accident.
The researchers used the tiny damsel fish to get their answer. They placed somme of them inside a specially-built tank and studied its behavior and eye diameter for six weeks while exposing them to herbivores and predators.
Before the experiment, the team took the measurement of the eyespot and eyeball then compared it to the body length. They found out that the measurements remained the same during the weeks that there were no predator cues then began increasing when they started exposing the fish to predators. The overall behavior of the fish changed as well.
"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," Lönnstedt said to Nature World News.
Those whose eyespots have grown in size also showed five times higher survival chance than those who did not.
She added, "We think the eyespots not only cause the predator to attack the wrong end of the fish, enabling it to escape by accelerating in the opposite direction, but also reduce the risk of fatal injury to the head."
The full details of the study may be read from Scientific Reports.
Damsel fish are known for its bright colors. They may grow up to 14 inches long. While most of them can be found in the ocean particularly in the coral reefs, there were some of them inhabiting the fresh waters as well.
