#fish science

In a study published earlier this month in the Proceedings of the Royal Society B, scientists from the University of Chicago have shown for the first time that pectoral fins in at least one species of fish possess neurons and cells that are extremely sensitive to touch. 

(A pictus catfish. Photo Credit: Adam Hardy, University of Chicago)

Of course, we are well aware of how sensitive and finely-tuned the human fingertip is, and how and even slight touches convey a great deal of information about our physical environment. It turns out that some fish use their pectoral fins in pretty much the same way.

The team studied the pictus catfish, a bottom-dweller from the Amazon River. Their question was simple: can fish feel things with their fins? Well, it looks like it!

Scientists used the flat end of a pin as well as a brush to stimulate the fish’s pectoral fins while measuring the resulting neural activity. They observed that not only the fish’s neurons responded to the touch, but they also conveyed information about the pressure being applied as well as the motion of the brush!

(A pictus catfish in motion. Gif source: ScienceLife University of Chicago)

There have been studies showing that fish possess the sense of proprioception, meaning they are aware of where their fins are relative to their bodies. This study however, is the first to show that fish fins can sense touch, and are able to sense light pressure and subtle motion, similar to mammalian skins.

“Like us, fish are able to feel the environment around them with their fins,“said  Melina Hale, another one of the authors. "Touch sensation may allow fish to live in dim environments, using touch to navigate when vision is limited.”

An analysis of the cellular structures of the fin revealed the presence of cells that closely resemble Merkel cells, which are associated with nerve endings in the skin of mammals and are essential for touch.

The team is currently conducting the same experiment with other species of fish (like flounders), but they are confident that such sensitivity to touch exists in other bottom-dweller fishes, and could be useful in nocturnal or deep-sea environments as well.