Hawaii's unique freshwater goby fish, Sicydium stimpsoni, use the suction power in their mouths to climb the cliffs behind waterfalls up to 100 meters high..
Still images of S. stimpsoni in (a) ventral and (b) lateral views
Researchers at Cornell University have determined that these tiny waterfall-climbing fish known as O'opu Nopili use the same set of muscles for both climbing and eating.The O'opu Nopili rock-climbing goby is known to inch its way up waterfalls as tall as 100 meters by using a combination of two suckers; one of these is an oral sucker also used for feeding on algae.
In their study, the Cornell researchers filmed jaw muscle movement in the fish while climbing and eating, and found that the overall movements were similar during both activities. While it is difficult to determine whether feeding movements were adapted for climbing, or vice versa, 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 behavior of these fish, climbing waterfalls with their mouth, might have been co-opted through evolution from a more basic behavior like feeding," says Richard Blob, lead author on the study.
