The Deep FOCE (dpFOCE) system performed in situ experiments in Fall 2011, including deep sea ocean chemistry and biology perturbation experiments. The effects of reduced pH on the feeding behavior of deep sea urchins (Strongylocentrotus fragilis) was evaluated under low pH (ΔpH= -0.3 units) and ambient conditions. Echinoderms are important components of benthic marine ecosystems, occupying roles as predators, grazers, detritivores, and filter feeders, as well as prey for higher trophic levels. They also reshape and reprocess benthic sediments. Echinoderms are thought to be highly sensitive to ocean acidification. Several reports have noted impacts of high CO2 levels on urchins, affecting rates of growth, survival, calcification, and mortality. dpFOCE is an ideal platform to explore long term, less-studied sub-lethal effects that may present as changes in normal movement, posture and feeding rates.