Effects of brain removal on integumental water permeability and ion content of the earthworm Lumbricus terrestris L

Abstract

The apparent integumental water permeability of nonhydrated Lumbricus terrestris is significantly greater than that of fully hydrated earthworms, which may act to reduce water losses in the soil. Apparent water permeability is significantly greater in decerebrate Lumbricus than in control worms. Hourly water exchange values ( K) are 2.28 for brainless and 1.71 for intact animals. Weight regulation in water and dehydration rates are the same in decerebrate and in control worms. However, when dehydrated and subsequently replaced in water, brainless animals have a 70% greater hydration rate and gain more weight than do control animals. Both total osmotic pressure and Cl − content of the coelomic fluid of fully hydrated earthworms are lower in brainless than in control animals. Brain removal tends to increase osmotic pressure in dehyrated Lumbricus, although not to a significant degree. Although the effects of brain removal suggest a neuroendocrine control of integumental water permeability in Lumbricus, the failure of reimplanted brains to have an effect leaves the hypothesis of such a control incompletely verified.