GOAD, A.J.*; EARLY, M.D.; SZYMIK, B.G.; PIRTLE, T.J.; Abilene Christian University; Abilene Christian University; Arizona State University; Abilene Christian University: Kinematic Analysis of Hermissenda Cerata Movement During Defensive Behavior

Aeolid nudibranch mulluscs have the unique ability to utilize the nematocysts from their cnidarian prey as a defensive mechanism. We observed that the aeolids, Hermissenda crassicornis and Flabellina trilineata direct the distal tips of their cerata toward noxious stimuli in a way that suggests that ceras movement is involved in defensive behavior. We used Hermissenda crassicornis because of their larger size as an experimental model to track the movement of individual cerata from three different animals and kinematically quantify the behavior. We glued Hermissenda to a Petri dish to immobilize the animal. The tethered Hermissenda were then placed in an aquarium having a visible calibrated grid on the bottom. We collected videographic data of the behavior evoked by applying calibrated filaments that deliver a known amount of force to the anterior of the animal. Two dimensional analyses of the data comparing the movement of the cerata relative to a defined region of the head suggest that the cerata movement occur in response to tactile stimuli and are directed toward the stimulus.