Discovering fish is evolving to prepare water to live on shore

You may not know, but some fish species are now evolving to live on the ground, and a new study has shown that they have migrated to hide from aquatic predators.

It is really a big challenge for a small fish to move from the familiar water environment to the dry ground. The first land-based organisms evolved about 390 million years ago, but there is still controversy surrounding why they decided to migrate to the mainland.

It is possible that they find better food sources on the ground, or escape unpredictable fluctuations of water quality, or simply jump ashore to avoid underwater predators. A recent study has shown that the final cause is completely grounded.

Biologists have found four fish species of the blenny family (a small tropical fish) that independently develop a "terrestrial lifestyle" , which means they divide the time of day for living underwater and living. land.

They fish blenny.

These species are found in tropical waters near Rarotonga, the largest island in the Cook Islands in the South Pacific. This is one of the few places in the world where more than one fish can live on land for a considerable period of time.

"Our study in Rarotonga is the first survey of the causes of fish moving to land," said ecologist and evolutionist Terry Ord from the University of New South Wales in Australia.

Researchers tracked three species of the blenny family to gather clues about what forced them to live on land. These fish swim around rocky rapids at low tide, but will move upwards at high tide. Even the amphibians of the blenny family still need water to breathe. When they jump on the coastal rocks, they still keep the fin moisture enough by taking water from the rocks.

They blenny have a lot of enemies in the water. They can be bait for species that live in coral reefs such as flounder, grouper, tuna and eel . Researchers find countless carnivores when the tide changes, and when water The tide is also when the blenny fish jumps onto the rocky shore.

"Life on the rocks is less dangerous for blenny fish, the worry comes mainly from birds , " Ord said.

Next, the team needs to test the hypothesis that fewer birds threaten to blenny fish than water predators. Scientists have counted the frequency of attacks on where blenny fish resided. They created 249 fake plastic blenny fish, then dispersed them both underwater and on land during high tide. As a result, terrestrial fake blenny is much less attacked, with only a few birds being attacked by birds.

Fish that evolved to live on land are more common than you think.

This is absolutely not surprising, because the islands in the South Pacific often have few terrestrial predators, which is really attractive for blenny fish.

"If you never look over the fence, you'll never know the grass is greener," Ord said. "However, if you are forced to the other side to escape something, you may realize that it has certain benefits, so you want to stay and adapt."

Ord's previous research and colleagues Georgina Cooke showed that fish evolving to live on land is more common than you think.

"A fish out of the water environment seems unusual, but the truth is that it is a fairly common phenomenon," Ord said last year. " Behavior in terrestrial life, when living underwater, has evolved over and over again to create a diversity of fish species today, and living on land is not as difficult as we thought."