Predation has been hypothesized to play a key role in the evolutionary and ecological history of crinoids. Whereas evidence of predation on crinoids in the form of injuries can be common, quantifying predation intensity, which is critical for properly evaluating such hypotheses, has proven challenging. Here, we used a longitudinal approach to quantify predation intensity on the extant, deep-water, stalked crinoid, Democrinus sp. The quantitative estimates are based on data collected from a manned submersible during expeditions conducted over a 3-yr span. These results indicate that this deep-water crinoid is subject to much lower predation intensity than are crinoids living in shallow water, consistent with (1) an inverse relationship between predation intensity and depth, and (2) the hypothesis that for stalked crinoids, which are unable to handle high predation intensity, deep water is a refugium.
Facilitation cascades create a predation refuge for biodiversity in a novel connected habitat
