A species of plec has been filmed using its powerful suckermouth to climb the sheer wall of a cave.
Researchers discovered a number of the plecs, determined to be Chaetostoma microps, climbing a steep flowstone waterfall in a cave in Ecuador, with some individuals at a height of almost 3m above the floor of the cave (scroll down for video). Loricariids and other fish have been known to climb rocks and waterfalls on surface streams but this is the first documented observation of any loricariid climbing in a cave — and the species concerned had only ever been recorded in waters above ground up until this point.
"It's not too surprising to find another catfish that climbs rocks. What is surprising is the environment that they are doing it in," Geoff Hoese, lead author of the study, told BBC News.
He added that there were some possible physical differences between the cave form and the surface dwelling form of C. microps, but that it was too early to speculate due to insufficient data at this point.
"But it's nice to think that we may be watching a small but significant evolutionary step as a species moves from one niche to another," he added.
As Chaetostoma have been shown to be more algivorous (Lujan et al. 2012), it seems unlikely that they inhabit the caves for extensive periods. However, flowstone features and rocks in cave streams may host microbial films that could be grazed, providing some nutrition.
The findings were published in the journal Subterranean Biology.
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