Casey Gilman

It's late and you're stuck in the office. Suddenly, the power goes out and you're plunged into darkness. How do you navigate in this low-light environment? The reflex response is to stick out your hands and feel your way around. The bumpy edge of your keyboard, the smooth surface of your desk, the cool roundness of the door knob: our fingertips can convey a lot of information about our surroundings. Turns out, we may have our fish cousins to thank for this fine-tuned sense of touch. Fish may not have fingers, but they certainly aren't without feeling! It's no surprise that fins transmit information like movement and position relative to the body (i.e. proprioception) back to the fish brain. However, Adam Hardy and colleagues from the University of Chicago, USA, wanted to see whether more detailed information about the environment could be sensed by fleshy fin membranes. The difficulty in addressing this question lies in the principal role of most fish fins, which is to get around. As touch is distinct from the proprioception experienced when swimming, the researchers needed a fish in which they could easily distinguish between these two senses. Their best bet was to find a species that might rely on a heightened sense of touch to survive, but which doesn't use all of its fins to swim. Luckily, they came across the pictus catfish, Pimelodus pictus. This bottomdweller spends its life lurking in the murky Amazon River. The catfish possesses a serrated spine along the front edge of its pectoral, or 'arm', fins, which Outside JEB is a monthly feature that reports the most exciting developments in experimental biology. Articles that have been selected and written by a team of active research scientists highlight the papers that JEB readers can't afford to miss.