Squid that are sensitized to pain by injury are quicker to flee from predators, showing an adaptive benefit to injury and pain.

Robyn Crook and Edgar Walters of the University of Texas Medical School at Houston and their colleagues took several squid (Doryteuthis pealeii; pictured) and inflicted a minor injury on one arm of each animal. When exposed to black sea bass, the previously injured squid fled or hid from these predators earlier than uninjured animals. But squid that were treated with anaesthetics before the injury, and so did not develop neural sensitization, failed to change their behaviour. As a result, these animals were less likely to survive encounters with the predator than injured individuals that were not anaesthetized. This is the first experimental evidence that pain-like neural sensitization is an adaptive response to injury, the authors say.

Credit: Roger T. Hanlon

Curr. Biol. http://doi.org/sp8 (2014)