September 30, 2013
SMS Undergraduate Awarded NSF Travel Grant
Late last week third-year SMS undergraduate Tyler Carrier was awarded $1,000 travel by the National Science Foundation to attend and present at the North American Echinoderm Conference held at the University of Western Florida in June 2014. Tyler’s talk will be titled: Responses of Dendraster excentricus larvae when exposed to Pleurobrachia bachei.
Between fertilization and settlement, marine invertebrate larvae can be transported great distances and encounter predators resulting in high mortality. In East Sound, Orcas Island, WA abundances of Dendraster excentricus echinoplutei and ctenophore Pleurobrachia bachei are inversely correlated. To gain insight on how potential predators may affect larval behavior we examined (1) predation rates of P. bachei on 4-, 6-, and 8-armed echinoplutei with and without competing prey items, (2) vertical distribution in response to initial P. bachei exposure, and (3) influence of P. bachei concentration and larval density on cloning rates. Results indicate that P. bachei did not prey on 4-, 6-, and 8-armed echinoplutei and the presence of P. bachei did not influence vertical distribution, but induced three cloning mechanism (budding, paratomy, and autotomy). Likelihood of cloning significantly increased by 1.3-fold with each larvae added and significantly decreased by 5.2-fold without the presence of P. bachei. It is suggested that a mucopolysaccharide produced by specialized colloblasts and mucus sensory cells of P. bachei causes physiological stress. This stress may increase defensive chemicals produced by echinoplutei, sensed within an aggregation, and increase likelihood of inducing cloning.