Air-breathing fish that can hop and walk across the floor on their fins* suggest that walking may have started underwater before such animals began migrating to land, scientists found.

    The distant ancestors of humans and all mammals, reptiles*, birds, amphibians* and other four-limbed animals, or tetrapods*, are fish that eventually developed the ability to breathe on land.

    One of the few living fish related to these ancient land-dwellers are air-breathers known as lungfish, which are found today in Africa, South America and Australia.

    Now scientists find that an African lungfish can lift its body clear off the floor and push itself forward using scrawny* “limbs,” abilities previously thought to have originated in early tetrapods.

    “This shows us — pardon the pun — the steps that are involved in the origin of walking,” said researcher Neil Shubin at the University of Chicago. “What we’re seeing in lungfish is a very nice example of how bottom-walking in fish living in water can easily come about in a very tetrapod-like pattern.”

    The lungfish in question has an eel-like body and a pair of flimsy* hind fins.

    “If you showed me the skeleton of this creature and asked me to make a bet on whether it walks or not, I would have bet it couldn’t,” Shubin said. “Their fins seem like the furthest thing from walking appendages* possible.”

    The lungfish’s history makes them popular pets among paleontologists*, and rumors circulated among scientists for years about walking behavior seen in these strange fish.

    To uncover the truth behind these stories, the researchers designed a special fish tank in which they could record a lungfish’s motions on camera from the side and below for in-depth analysis.

    Their videos revealed the lungfish commonly used its hind or pelvic limbs to “bound,” moving both limbs at once like one would hop, and to “walk,” alternating* limb motions.

    The forelimbs look similar to the hind limbs, but were not used in such bounding and walking movements.

    This discovery might redraw the evolutionary route scientists think life took from water to land. Many of the steps needed to adapt to surface-dwelling could have happened millions of years before early tetrapods developed limbs with digits* and took their first steps on shore. (SD-Agencies)