Growth, Metamorphosis, and Gape-limited Cannibalism and Predation on Tadpoles in Larvae of Salamanders Hynobius retardatus

Growth, metamorphosis, and gape-limited cannibalism and predation on tadpoles (Rana pirica) in larvae of salamanders (Hynobius retardatus) were investigated in laboratory. Larval period and the size at metamorphosis were correlated positively to one another in the salamanders. When embryos were exposed to low temperature, larval period were prolonged and the size at metamorphosis increased in the salamanders while larval period were extended and the size at metamorphosis decreased in the frogs. Salamander larvae reared in group had shorter larval period and smaller size at metamorphosis than those reared individually. Small salamander larvae were more vulnerable to cannibalism and mutilation than large ones. Tadpoles incurred high probability of predation and mutilation by salamander larvae even when the head widths of tadpoles attained the maximum sizes.