New research published in the open access peer reviewed journal Public Library of Science on Jan. 4, 2013, is the first examination of the common mechanism of feeding and climbing exhibited in the Hawaiian waterfall-climbing fish Sicyopterus stimpsoni.
Sicyopterus stimpsoni are known to climb waterfalls as high as 300 feet and more.
A combination of suckers in the mouth and a ventral sucker, common to all gobies, formed from the fusion of the pelvic fins.
The eggs of the fish develop in the ocean and the young fish are constrained by a change in feeding to a preference for algae to scale the heights of waterfalls.
The researchers examined the feeding behavior and the climbing behavior and noted physical and kinetic differences in feeding and climbing were small. The unique ability is considered to be a demonstration of the evolutionary adaptation called exaptation. The researchers cannot specifically determine which behavior came first.
In exaptation one trait evolves to provide for a single function and then may be co-opted to accommodate a different or secondary function when the animal experiences a change in habitat.
One potential source of the dual function of climbing and algae eating may have been the volatile nature of the volcanic islands that Sicyopterus stimpsoni inhabits.
Heiko L. Schoenfuss, Aquatic Toxicology Laboratory, Saint Cloud State University, St. Cloud, Minnesota, United States of America, Joshua A. Cullen, Takashi Maie, Richard W. Blob*, Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
Citation: Cullen JA, Maie T, Schoenfuss HL, Blob RW (2013) Evolutionary Novelty versus Exaptation: Oral Kinematics in Feeding versus Climbing in the Waterfall-Climbing Hawaiian Goby Sicyopterus stimpsoni. PLoS ONE 8(1): e53274. doi:10.1371/journal.pone.0053274