Research sometimes means looking for one thing and finding another. Such was the case when biology professor Alice Gibb and her research team at Northern Arizona University witnessed a small amphibious fish, the mangrove rivulus, jump with apparent skill and purpose out of a small net and back into the water.
This was no random flop, like you might see from a trout that's just been landed. The rivulus seemed to know what it was doing.
They hadn't expected to see that behavior, even from a fish known to spend time out of the water. So before long, what began as a study on the evolution of feeding behavior was shifted to a study of how fish behave when stranded on land. And considering what is implied by the truism "like a fish out of water," the results came as another surprise.
Some fully aquatic fishes, as the author's video clips show, also can jump effectively on land even without specialized anatomical attributes. This has significant implications for evolutionary biology, Gibb said, because the finding implies that "the invasion of the land by vertebrates may have occurred much more frequently than has been previously thought."
The study is summarized in a paper, "Like a Fish out of Water: Terrestrial Jumping by Fully Aquatic Fishes," that appears online in the JEZ A: Ecological Genetics and Physiology.
Gibb said the study "supports a big-picture theory in evolution," which is that the nervous system, in its control of bones and muscles, can allow a new behavior to appear without necessarily bringing about a physical change.
In the case of aquatic fish, Gibb said, "This shows that you don't have to have legs or rigid pectoral fins to move around on land. So if you go back and look at the fossil record to try to say which fish could move around on land, you'd have a hard time knowing for sure."
The original feeding study began with guppies, then moved to a relative, the mangrove riv
|Contact: Eric Dieterle|
Northern Arizona University