Coping with the Cold
When it’s chilly, we pile on thick coats and wool socks to keep warm. But what do the creatures living on our beaches do to cope with the cold? Intertidal invertebrates like starfish and sea anemones can be exposed to very cold air during high tide. Between high and low tide, they experience large changes in ambient temperature and can even have their bodies frozen.
Intertidal invertebrates can either be freeze-tolerant or exhibit freeze-avoidance. Freeze-tolerant animals are able to withstand ice crystals growing inside their bodies and can remain undamaged when as much as 65 percent of their body water is frozen! Freeze-avoiders withstand cold temperatures by supercooling (cooling below freezing point without solidifying) the liquid in their bodies and using antifreeze compounds in their blood.
Viewer Tip: Up to 60 percent of the human body is made up of water — could you imagine that water becoming ice inside your body? Mammals don’t have these kinds of adaptations, so be sure to dress appropriately for chilly weather!
Season: Winter
(Sources: Willmer P, Stone G, Johnston I. 2005. Environmental Physiology of Animals, 2nd ed.; http://ga.water.usgs.gov/edu/propertyyou.html)
