Colour, sunlight and internal temperatures in the land-snail Cepaea nemoralis (L.).

The literature on the effects of pigmentation on radiant energy absorption and temperature in poikilothermic animals is reviewed. Some of the difficulties encountered in studies of this type are described.Mercury-filled shells and live snails of different colours were exposed to sunlight. Darker-pigmented shells were almost always hotter than lighter shells. Large differences in pigmentation (yellow compared with brown, yellow unbanded compared with yellow banded) led to more pronounced differences in temperatures than did small differences in pigmentation (yellow compared with pink, pink compared with brown).