Student Research Projects

Behavioral Responses of Neotropical Harvestmen to Invertebrate Predators

Student Dayna Cook and Adam Smith
Faculty Mentor(s)
Department Biology
Course BIO 489: Research in the Natural Sciences


Descriptions of defensive behaviors employed by Neotropical harvestmen are rarely based upon direct observations of encounters between harvestmen and syntopic invertebrate predators. In this study, we investigated the defensive behaviors exhibited by five species of harvestmen in interactions with spiders (Cupiennius coccineus), amblypygyids (Phrynus pseudoparvulus), onychophorans (Epiperipatus sp.), and centipedes (Scolopendra sp.). As a control, we also observed interactions between harvestmen and the millipede Nyssodesmus python. Ctenid spiders were the most successful predators, consuming 11 harvestmen (out of 64 trials) including representatives of three species and two families (Cosmetidae and Sclerosomatidae). In the presence of arthropod predators, the most frequent defensive behavior exhibited by harvestmen was fleeing. Other defensive behaviors included aggression (leg swatting), bobbing, leg autotomy, lying flat, and thanatosis. Prionostemma sp. Exhibited the most variability with respect to secondary defensive behaviors.