The body of sea stars helps buffer thermal variations experienced in low tide by taking up and storing cold sea water during high tide.

"One starfish has a remarkable strategy to avoid overheating in the sun, scientists have discovered.

"The starfish pumps itself up with cold seawater to lower its body temperature when exposed to the sun at low tide.

"It is equivalent to a person drinking seven litres of water before heading into the midday sun, scientists say" (Bourton 2009)


"The body temperature of ectotherms is influenced by the interaction of abiotic conditions, morphology, and behavior. Although organisms living in different thermal habitats may exhibit morphological plasticity or move from unfavorable locations, there are few examples of animals adjusting their thermal properties in response to short-term changes in local conditions. Here, we show that the intertidal sea star Pisaster ochraceus modulates its thermal inertia in response to prior thermal exposure. After exposure to high body temperature at low tide, sea stars increase the amount of colder-than-air fluid in their coelomic cavity when submerged during high tide, resulting in a lower body temperature during the subsequent low tide. Moreover, this buffering capacity is more effective when seawater is cold during the previous high tide. This ability to modify the volume of coelomic fluid provides sea stars with a novel thermoregulatory 'backup' when faced with prolonged exposure to elevated aerial temperatures." (Pincebourde et al. 2009:890)

Starfish 'pump up' to cool down

Journal article
An Intertidal Sea Star Adjusts Thermal Inertia to Avoid Extreme Body TemperaturesThe American NaturalistFebruary 23, 2017
Sylvain Pincebourde, Eric Sanford, Brian Helmuth