Physiological responses of intertidal starfish when exposed at low tide

Physiological responses of the intertidal starfish Pisaster ochraceus (Brandt, 1835) to emersion at different temperatures.

Dr. Iain McGaw (Memorial University), Alex Clifford and Dr. Greg Goss (University of Alberta) investigated physiological responses of Pisaster ocraceus to emersion at range of air temperatures, followed immersion in ambient seawater temperatures to examine physiological processes that occur when sea stars are exposed to high air temperatures during low tide.

The authors report that although there were some disruptions to gas transfer and acid–base balance during emersion they were not extensive. These, coupled with behavioural selection of crevices and vertical rock faces to reduce exposure to the hot sun, suggest that for the most part P. ochraceus is not living close to it’s physiological limits during the 4–6 h of emersion it typically experiences in the intertidal zone.

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photo: J. Reynolds