Goby fins are as touch sensitive as human fingertips

Nov. 3 (UPI) -- Primate fingertips are incredibly touch sensitive. According to a new study published in the Journal of Experimental Biology, the fins of gobies are too.

From the moment of birth, humans start grabbing and touching. The ability to experience and manipulate the world through touch is one of the qualities that make humans and their closest primate relatives unique.

It turns out, however, that some fish are also quite touch sensitive.

"A whole host of fishes contact the bottom of bodies of water, plants or other animals using their fins," lead study author Adam Hardy, biology graduate student at the University of Chicago, said in a news release.

For the study, researchers chose to examine the touch sensitivity of the round goby, Neogobius melanostomus.

"Round gobies were a great choice for these experiments given that they are a bottom-dwelling fish that love to perch on rocks and other materials," said Hardy.

During the summer, Hardy biked from the lab to Lake Michigan to catch round gobies, an invasive species in the Great Lakes, for the study.

"It's always a good day when you can go fishing for work," he said.

Back in the lab, Hardy observed the fish as they splayed their fins flat -- like the palm of a hand -- across different materials in the fish tanks he had placed them in.

Hardy used a short horizontal bar to measure the electrical signals in nerve endings positioned along the fins of the round gobies. As he moved the bar along the fin rays, toward the fin tips, the electrical signals spiked, suggesting the fins were touch sensitive.

To see if goby fins were sensitive enough to detect differences in the texture of types of gravel beds, Hardy rolled a wheel with differently spaced ridges along the fins of the captured fish. The electrical signals proved the nerve endings sensed each ridge.

"They matched the pattern of the ridges moving across the skin even as the speed of the wheel increased," Hard said.

The electrical signals proved the fins of gobies are as touch sensitive as the fingertips of primates.

"Primates are often held up as the gold standard in tactile sensitivity, so it was really exciting to see that fish fins exhibit a similar tactile response," Hardy said. "This primate hand-like touch also suggests that the ability to detect surface differences via touch has been around a lot longer than we previously thought."