How do salamanders fertilize their eggs internally?

Most salamanders achieve internal fertilization without the use of intromittent (copulatory) organs. Instead, the male produces a spermatophore—a specialized sperm case consisting of a gelatinous base topped with a sperm cap.123

During courtship, the male deposits one or more of these spermatophores onto the ground or another surface. The female then moves over the spermatophore and takes the sperm mass into her cloaca. Once inside, the sperm may be used to fertilize eggs shortly after mating, or it may be stored within the female's body for several months before fertilization occurs.31

It is important to note that this process of internal fertilization is not universal among all salamanders. Members of the suborder Cryptobranchoidea utilize external fertilization, where the male sheds milt over eggs deposited by the female.23