The Cephalorhynchus dolphins are among the smallest dolphins. Indeed, in length, Hector's dolphins from New Zealand's South Island (maximum 145 cm; ca. 50 kg) and South American Commerson's dolphins (maximum 146 cm; ca. 45 kg) are the smallest of all dophins. Both Hector's and Commerson's dolphins have isolated populations in which individuals grow larger. In both Hector's and Commerson's dolphins females are 5-10% larger than males.