Could Walking Fish Hold Key to Evolution?

Could an unusual fish that walks hold secrets to evolution of animals, including humans?

Ancient fish first came onto land around 400 million years ago. These tetrapods had four legs, and were distant ancestors to all land animals alive today, including human beings.

The species that first made its way onto dry land went extinct long ago, making live specimens unavailable for study. In their place, researchers studied the bichir, an African fish that breathes air and propels itself with stubby fins.

Biologists raised juvenile members of the species on “dry land.” To keep the animals a live, a small amount of water was provided in the bottom of an aquarium. A mister kept the artificial environment moist. They then compared development of the fish to those that grew up in water.

The McGill University researchers found the animals raised out of water developed in a significantly different manner than normal. Their fins grew closer to their bodies. They were able to scurry along on land much faster than their water-borne cousins. Their tails also moved less than normal.

Emily Standen, a researcher on the study, stated, “I’m very surprised the fish survived so well on land. That was an initial gamble with this experiment — could the fish even be raised on land?”

At the time fish came on land, there was a great deal of biodiversity among marine life. This could have led to great competition of fish, driving some onto the land.

If the first few generations of fish coming up on shore showed similar development, these traits may have been passed on to offspring.

Standen and her team will next study the fish as they live through several generations, to examine how the ability to walk in land may be passed to descendants.