Cold has long been regarded as inimicable to life. From the speculations of the earliest geographers and explorers to the azoic hypothesis of Edward Forbes, it was widely believed that the frozen polar regions and the cold, dark depths of the ocean would be essentially devoid of life. Even today, the richness of some polar marine invertebrate assemblages comes as a surprise to many. The tropics are still regarded as a less demanding environment, at least for marine organisms, and many palaeoecologists continue to refer to a cooling of the climate as ‘deterioration’ and a warming as ‘amelioration’.

The first physiologists to study polar marine organisms naturally turned their attention to the key areas of how teleost fish avoided freezing when living in waters significantly colder than the equilibrium freezing point of their body fluids, and how marine ectotherms managed to sustain metabolic activity at low temperatures (Scholander et ai, 1953; Wohlschlag, 1960). In the marine environment, the avoidance of freezing is a peculiarly polar problem, and the essential mechanism was first elucidated in Antarctic fish by DeVries (DeVries & Wohlschlag, 1969; DeVries, 1971). Subsequent work on Arctic fish showed that most northern taxa utilised antifreeze proteins in contrast to the antifreeze glycoproteins of Antarctic notothenioids and the true cods (gadoids), thereby revealing an intriguing case of parallel evolution (Scott, Fletcher & Davies, 1986; Eastman, 1993).

In the terrestrial environment, exposure to freezing temperatures is a widespread environmental challenge. In contrast, for marine organisms freezing is essentially a problem only for polar teleost fish, intertidal organisms and those high latitude benthic invertebrates which become encased in anchorice.