Read More: Mysterious Universe
Why did some fish flip out of the water 400 million years ago and evolve into land creatures? We may soon find out … with our own eyes. Researchers in Australia have discovered several species of tropical fish that seem able to survive out of water for long periods of time and do it by choice, particularly during high tide. This can’t be good. Our study of blennies on Rarotonga is the first to examine the pressures driving fish out of the water. Evolutionary ecologist Terry Ord from the University of New South Wales seems to agree that this can’t be good. He’s the co-author of a study in The American Naturalist which details a research project on four species of blennies, an odd-looking eel-like fish that typically spends most of its time on the sea floor. However, the blennies around Rarotonga, the largest of the Cook Islands in the South Pacific Ocean, have been found far above the sea bed — on land, and particularly during high tide. While these blennies still breathe through their gills, they mange to get oxygen on land from ocean spray and small puddles. Why high tide? As the tide came in and the rock shelf became submerged, most of the blennies moved to higher ground, above the high tide mark, apparently to avoid being eaten by the aquatic predators coming in with the rising water. These smart fish are getting out of the water to escape the flounders, groupers, wrasses and moray eels that feed on them. This is not a random occurrence but one that has been observed regularly at high tide. But is the seaweed truly greener on the other side of the water? Aren’t there predators on land that might like a blenny and chips minus the chips?