Light Preference in Sea Stars

Our research project is finally underway! Isabel, Hannah, Lindsay and I are investigating light preference in Asterias rubens, or common sea stars. Over the past few days, we’ve been working on experimental setup and material collection, which includes finding Asterias rubens and Mytilus edulis, or mussels—sea stars’ preferred food source.

Last Saturday, we conducted our second transect study at Transect Site 19, an exposed intertidal zone that houses an abundance of mussels. Mytilus edulis are well suited to its high-stress environment, and use byssal threads to anchor themselves to rocks to protect against the increased wave action. After the study, we collected as many mussels as we could fit in Colton’s pockets and brought them back to the lab.

Unfortunately, we still only had 4 sea stars (the ones that were already in the sea table). We recruited our classmates to help us look for more during low tides, particularly in the lower intertidal zones and around/under Laminaria digitata (brown kelp). However, after a series of unsuccessful hunts for Asterias rubens, we were fortunate enough to get permission to use five of the sea stars in the neighboring lab classroom.

After naming each of our nine stars—Dwight, Guy, Billy, Charlie, Gerald, Jay, Rolf, Steve, and Stan—we measured their central disk and average arm size (for identification purposes), and placed them in a holding tank. (see Steve, Rolf, and Gerald below)

Control variables in our experiment include feeding times, number of trials, water quality, etc. In order to ensure consistent water conditions in both the sea stars’ natural habitat and our experimental tanks, we went to Smith’s Cove yesterday to test water salinity, pH, dissolved oxygen, and temperature. We will compare this data to the water quality measurements of the sea table to evaluate whether differences in water conditions may have an effect on our results.