The effect of ambient light on blind cave crayfish: Social interactions

This study investigated the social behaviors of blind cave-adapted crayfish and compared them to the behaviors of sighted crayfish. Because blind cave crayfish display phototactic behavior, presumably mediated by the caudal photoreceptors in the sixth abdominal ganglion, we tested whether light, a disturbance in the crayfish's normal cave environment, altered their normal social behaviors. Observations were made in infrared or dim-white light to quantify social interactions. Exposure to white light reduced the amount of interaction time as compared to infrared light. The results revealed that blind crayfish did not exhibit behaviors usually associated with visual displays and posturing (i.e., the raised meral spread was absent). Same-sized individuals, previously housed in isolated conditions for two weeks, were paired. Both individuals tended to tail flip or move apart immediately after initial antennae contact. This is the same behavior observed within the natural cave environment. After repeated interactions between them, the rapid tail flip behavior became less frequent, while avoidance became an automatic reaction. Ethograms were constructed to determine the differences in the observed behaviors between the aggressive and submissive cave crayfish.