Developmental Effects of Predator Cues on Dendraster excentricus Larvae: The Effects of Pugettia producta Effluent and Crustacean Dominant Plankton Effluent

Abstract

Previous findings supporting increased cloning in Dendraster excentricus (D. excentricus) larvae as a response to predator cues, in particular fish slime. Such findings report a “visual predator hypothesis”, suggesting that the larvae clone in order to become smaller and thereby avoid visual predators and possibly even non-visual predators. The experiment reported here builds upon earlier findings by studying the exposure of D. excentricus larvae to a kelp crab effluent (using Pugettia producta) and a crustacean dominant plankton effluent. Individual larvae were exposed to one of three treatments: the kelp crab effluent, plankton effluent, or filtered sea water, for approximately 66 hours. After this period, number of clones, number of larval arms, and the rudiment stage of each larvae was determined. Linear modeling showed significant results when comparing the kelp crab treatment to the control for cloning (p=0.024) and rudiment stage (p=0.032); they also displayed significant differences for larval arm stage when comparing both the kelp crab effluent treatment (p= <0.001) and plankton effluent treatment (p<0.001) to the control. These findings may support the visual predator theory, depending on whether D. excentricus larvae are able to differentiate predator cues, and, if so, to what specificity.