Abstract1_4 (Hasumi)

Hasumi, M., and H. Iwasawa: Wandering behavior and cutaneous changes in winter-dormant male salamanders (Hynobius nigrescens). Herpetologica (USA, International) 48(3): 279-287, September 1992. Stable URL

Abstract: Frequent wandering of prebreeding male Hynobius nigrescens was monitored experimentally; salamanders moved in and out of the water many times regardless of the type of treatment (i.e., saline or prolactin), suggesting flaws in the theory of water drive. The number of submerged animals in the saline-injected group varied in approximate coincidence with the air temperature. Prolactin (PRL)-injected animals remained submerged longer than saline-injected ones, exhibiting a preference for an aquatic habitat but not a movement into the water. Cornified epidermis and dermal mucous glands filled with mucus were the characteristics of winter-dormant, terrestrial phase animals, but in all of the PRL-injected animals, the cornified epidermis disappeared and mucous glands were empty regardless of habitat (i.e., terrestrial or aquatic). The hypodermic connective tissue was dense in both hibernating animals and PRL-injected animals kept in a terrestrial habitat, which were free of water, but loose in some of the individuals in an aquatic environment. These results of cutaneous changes do not support the hypothesis presented by Moriya that PRL induces a remarkable enlargement of hypodermic tissue, causing the animals to migrate from land to water.