(Photo: Wikimedia Commons)
Researchers from the University of Chicago found that the fins of round gobies can detect textures with a sensitivity similar to that of the fingertips of monkeys.
The details of the study were published in the Journal of Experimental Biology.
We know very little about the sense of touch of aquatic animals, but for fish, fins are more than motor structures. It is becoming increasingly clear that fins play an important sensory role.
The similarities between distant species suggest a common ancestor that possessed the ability to sense physical forces. It probably had limbs that eventually evolved into fins, arms, and legs.
The researches measured nerve activity in the fins of round gobies (Neogobius melanostomus) with the intention to know if the fish could sense texture with their fins.
In nature, round gobies move the underside and rest there on their large pectoral fins.
The researchers sacrificed 6 gobies and worked with their fins.
They registered electrical spikes in their nerves as a bumpy plastic ring attached to a motor rolled slightly above each fin.
A saline solution kept the nerves working as they would if they were in a live fish.
Different spaces provided information on the range of roughness that the fins could detect.
The narrower spaces mimicked the texture of coarse sand and the larger openings produced a roughness on the scale of pebbles.
The periodic patterns of the neural spikes corresponded to the spacing of the ridges.
The more widely spaced ridges produced more frequent sets of peaks, while the larger gaps produced less frequent bursts of electrical activity.
These signals also varied with the speed of the rotating ring. Together, these results suggest that goby fins respond to the different textures they encounter.
These peak patterns were similar to those recorded by other researchers in monkey finger tests.
The scientist hope to develop better robots. The discoveries could lead to swimming robot designs that detect underwater objects and can explore hard-to-reach areas.
Sources:
- NewScientist: https://www.newscientist.com/article/2258760-some-fish-fins-are-as-sensitive-to-touch-as-human-fingertips/
- Journal of Experimental Biology: https://jeb.biologists.org/content/223/21/jeb227280