Thursday, May 10, 2012, third entry – The Florida Tech Biological Oceanography students had a lab task when they returned from South Cove. They had to take turns exposing intertidal prey to different intertidal predators and record their responses. Have you ever seen an urchin stampede? They move incredibly slow on their purple tube feet. Their predator, the sunflower star Pycnopodia helianthoides, moves a little faster, but that doesn’t stop the urchins from trying to “run” for it when they sense chemically that the Sunflower Star is nearby.
Pycnopodia is one of the great feared predators of the rocky intertidal. It is enormous (up to a meter in diameter!) and has a ravenous appetite, eating molluscs, urchins, and even other sea stars and crabs. We only collected a medium to small one for our experiments – the big one is just too difficult to keep in the sea tables in the lab. The Florida Tech Biological Oceanography students also gauged the responses of snails, clams, shrimp, and limpets to the presence of Pycnopodia. Most did not give a dramatic response, but the snails seemed to turn and the clams attempted to flip away with their disproportionately large foot.
The Biological Oceanography students from Florida Tech seemed to enjoy exposing the prey to potential predators to gauge response, but they were compassionate and didn’t want to see actual death (“no-marine-invertebrates-were-harmed-in-the-conducting-of-these-experiements”).