Predator Avoidance Behaviors of Physella acuta

The senses of prey animals have been finely tuned by natural selection to detect potential predators before a predation attempt is begun. For aquatic invertebrates, chemosensation is the primary means by which predators are detected. However, in polluted waters, the chemosensory abilities of prey animals may be negatively impacted through interference. In such cases, prey animals may not be able to sense predators before a predation attempt. This study investigates predator avoidance behaviors of Physella acuta, a freshwater snail, exposed to two potential predators and scent of a distressed conspecific in both clean and polluted waters. Snails were observed in isolation for a period of thirty minutes. The first ten minutes allowed snails to acclimate to the new tank. In the second ten minutes we recorded the snail’s movement in the absence of predator information. Prior to the third ten minutes, we added scent of a predaceous giant water bug, crayfish, or water (control) and then continued recording snail behavior. We observed no significant difference in movement and behavior after the addition of giant water bug scent and water. However, there was significant decrease in movement after addition of crayfish scent, with some snails escaping to dry areas in the test tank. Tests in polluted water, where Physella acuta may be unable to use chemosensation (effectively), are forthcoming.