Developmental stages and growth rate of the mole Talpa occidentalis (Insectivora, Mammalia)

Abstract

Moles are the only fertile true hermaphrodites described up to now among mammals. This paper investigates the development and growth of the mole Talpa occidentalis. Fifteen developmental stages (8 prenatal and 7 postnatal) were established and 12 of them, ranging from early gestation to weaning, are described in detail. The growth of moles was shown to fit triphasic curves for both males and females. The coefficient of reproductive effort of females, defined as mass of the litter at weaning relative to maternal body mass, is inversely proportional to mass of the female, according to an exponential function. Compared with other insectivores with lower body mass (shrews), this coefficient in female moles (2.69) is significantly higher than expected (1.91), which implies that reproductive effort of moles is 36% greater. This study provides the chronological criteria (based on body mass, crown-rump length, and major external morphological features) needed for age determination of individual developing moles and thus represents a useful tool for further studies in these mammals.