Predator Induced Plasticity in Barnacle Shell Morphology
Department of Biology (Contributor), Jarrett, Jeremiah N. (Contributor), Leone, Stacy E. (Creator)
Organisms employ inducible defenses to prevent predation. This occurs when the organism recognizes an environmental cue that leads to the expression of the defensive trait. In marine systems this cue is often chemical in nature. Several marine invertebrates have been shown to use inducible defenses, including: bryozoans, mussels, snails, and barnacles (Harvell 1984, Lively 1986, Trussell 1996, Leonard et al. 1999, Dalziel and Boulding 2005, Jarrett 2008). The purpose of this study was to determine if the cue from exposure to Mexacanthina lugubris, a predatory snail, causes the narrow operculum morphology in the barnacle Chthamalus fissus. Rocks containing juveniles of the species C. fissus were collected in La Jolla, CA. In the laboratory the barnacles were assigned to one of three treatments: M. lugubris (predator), Tegula funebralis (herbivore), or control. The barnacles in the predator and herbivore treatment were exposed to cues from the snails for 28 days over a 35 day period. The barnacles in the control treatment were exposed to the same conditions without the presence of any snails. Digital photographs of the barnacles were taken on 1 August 2007 and 23 January 2008. Measurements of operculum width, operculum length, and basal diameter were taken using Sigma Scan Pro 5TM software and compared among the treatments. Over the course of the experiment, barnacles that were exposed to M. lugubris developed significantly narrower opercula than barnacles in the T. funebralis and control treatments. This indicates that the narrow operculum morphology seen in C. fissus is an inducible defense triggered by a cue from its predator, M. lugubris. Future studies are needed to determine the cost of employing the narrow morphology, to investigate the nature of the cue and the effects of damaged conspecifics on the development of the narrow morphology, and to determine how genetic variation in populations of barnacles influences their ability to respond to invasive predators
Downloadable Archival Material, English, 2008
Central Connecticut State University, 2008