Science: Fish landfalls have evolved independently at least 30 times

The Mauritian alticus monochrus happily broke free from the shackles of water, and it is definitely not the only one. Image credit: G. Cooke

350 million years ago, the first fish landed was not a fluke. According to a new study on the diversity of extant amphibian fish, our friends from the ocean have evolved the ability to make landfalls at least 30 times from ancient times to the present. Their work focuses on the factors that have contributed to the dramatic shift in fish habits, which may provide clues to the question of how fish first landed.

Sandy Kawano, a comparative biomechanicist from the National Institute for Mathematical and Biological Synthesis in Knoxville, Tennessee, who was not involved in the study, said, "Unexpectedly, these shifts may not be as difficult as previously speculated." ”

Terry Ord and Georgina Cooke of the University of NewSouth Wales in Kensington, Australia, delve into many scientific papers on successful fish landings for the study. This allows them to count the number of times modern fish adapt to life on shore and determine whether these terrestrial fish have something in common.

The duo found 130 species of fish with varying degrees of land activity, an Anguilla rostrata that swims between different ponds after rain, Taurulus bubalis, a colorful coastal fish that jumps out of the tide pool under hypoxic conditions, and Periophthalmus barbarous fish that crawls in mud pools with spherical eyes and arm-like fins.

Fish lineages are full of examples, with a June 2016 study published in Evolution that found that 33 families contained at least one species of fish attracted to the earth. From this, the authors say, there is reason to conclude that landing evolution has occurred at least so many times.

In order to construct a more complete family tree, the authors studied a group of coastal fish that are particularly fond of terrestrial life, the rayfish, in the field, which deserves our special attention. The team found that the rays had made at least three, and possibly even seven, successful landings. Pacific jumping fish (Alticus arnoldorum) are among the best, and as adults they have suction cup-like fins that help them hold their ground under the lapping of the waves, and they jump between rocks and mate. These rays are so disgusted with the water that if you go after them, "they'll flee deeper into the reef." Ord said.

In studying the fish, the two men discovered that two catfish species classified as "sea creatures" actually spend a considerable amount of time on land. Ord claims that if this phenomenon is also typical in other fish groups that the researchers found to have land-loving tendencies, the estimate of the number of terrestrial fish that have evolved may be much higher than 33.

Kawano praised the team's integration of data ranging from papers to field findings, and pointed to the ecological diversity of pro-land species.

However, the shift toward terrestriality seems to occur more during the intertidal zone: areas that are covered by water at high tide and exposed after low tide. Michel Laurin, a paleontologist at the French National Institute of Research (CNRS) from Paris, says the discovery may provide clues to our exploration of the habits of our ancestors. The old view, which is still supported by some, speculates that the adventures of the first terrestrial fish were from fresh water. Laurin says, however, "All recent discoveries suggest that our ancestors came from the sea. "We know that the intertidal zone looks like a base for landings today, and maybe hundreds of millions of years ago it was.

Original link:

Fish may have evolved to live on land more than 30 times

Excerpt from the original article:

The first fish that stepped onto land more than 350 million years ago wasn’t a fluke. Our ocean friends may have evolved the ability to come out of the water at least 30 times over the ages, according to a new study of the diversity of amphibious fish alive today. The work highlights the factors that foster extreme lifestyle changes—and may hint at how the very first fish took to land.