Water Exchange in the Mantle of A Terrestrial Snail During Periods of Reduced Evaporative Loss

Based on surface temperature, steady-state rates of evaporation of the mantle of inactive Otala lactea are very low even down to 1·5 % relative humidity. Mantle permeability is 0·016 mg/cm2/h per mmHg vapour pressure difference. Marked peaks in surface temperature following humidity change are interpreted as net gain or loss of water to the mantle. Smaller fluctuations in surface temperature are interpreted as limited mucusgland activity. The existence of a superficial hygroscopic layer overlying an impermeable barrier in the mantle is discussed.