The Nopili rock-climbing goby is known to inch its way up waterfalls as tall as 100 metres by using a combination of two suckers; one of these is an oral sucker also used for feeding on algae.
Researchers from Clemson University filmed jaw muscle movement in these fish while climbing and eating, and found that the overall movements were similar during both activities.
They found that it is difficult to determine whether feeding movements were adapted for climbing, or vice versa with the current data, but the similarities are consistent with the idea that these fish have learned to use the same muscles to meet two very different needs of their unique lifestyle.
"We found it fascinating that this extreme behaviour of these fish, climbing waterfalls with their mouth, might have been coopted through evolution from a more basic behaviour like feeding," lead author on the study Richard Blob said.
"The first step in testing this was to measure whether the two behaviours really were as similar as they looked," Blob said.
The research published in the journal PLOS ONE.
