How Fish Evolved to Climb Waterfalls With Their Mouths
Hawaiian fish uses same mechanism to climb and eat, study says.
The inch-long (2.5 centimeter) fish uses suckers in its mouth and belly to move up steep cliffs in its rugged Hawaiian habitat. (Related "pictures: "'Walking' Fish a Model of Evolution in Action.")
Because its freshwater habitat is easily disturbed—by a big storm, for instance—the fish often crawl up waterfalls to return upstream.
But how this odd creature evolved to trek vertical distances of up to a hundred feet (30 meters)—the energetic equivalent of a person running a marathon—was unknown, said Richard Blob, an evolutionary biologist at Clemson University.
Now, a new paper by Blob and colleagues in the journal PLOS ONE shows that the fish uses the same movements to climb as it does to eat algae.