Integument permeability of crabs and adaptation to land

1. 1. Most of the evaporative water loss of land and aquatic crabs occurs through the shell. Applications of petroleum jelly to the integument usually reduced evaporation over 50 per cent. Losses from dead crabs were virtually the same as living crabs. 2. 2. The permeability of pieces of shell from eight species were correlated with the crab's habitats; terrestrial forms were least permeable while aquatic species were most permeable to water.