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Fluctuating temperatures and temperature acclimation are key components of an organism’s environment and its ability to move within it. Effects of temperature on gait were studied in the sea star Asterias forbesi, which live in intertidal and subtidal habitats where they are exposed to substantial temperature fluctuations due to tidal cycles, seasonal variation and climate change. A novel oscillatory gait for sea stars was discovered in 2012 and has only been studied at one temperature (13°C) for A. forbesi. A. forbesi from the Gulf of Maine were acclimated for a minimum of two weeks to one of three temperatures – 8°C, 13°C, 18°C – and for each acclimation group, locomotion and righting response were studied at the same three experimental temperatures. The speed, speed amplitude and frequency of the gait were lower at the 8°C experimental temperature compared to the other two temperatures, and were associated with less frequent use of the oscillatory gait. However, 13°C and 18°C experimental temperatures did not have a significantly different effect on the sea star’s gait. A decrease in temperature sensitivity as temperature rises has been well-studied in a variety of marine ectotherms, especially those that live in the intertidal. A subtle influence of acclimation temperature was detected in our study, where 18°C-acclimated sea stars experienced lower frequency across experimental temperatures and greater lengthening in righting time at colder experimental temperatures. Data from a wider range of experimental temperatures would be necessary to confirm the extent to which A. forbesi exhibit temperature-independence at higher temperatures in their thermal range, as well as identifying the thermal upper limit beyond which locomotion becomes suboptimal. The results of this study have interesting ecological implications for the sea stars’ ability to employ this newly-discovered gait in their natural environment, across a range of seasons and temperatures.
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