Common dolphins have also been known to dive below schools and drive them to the surface. They push their prey completely out of the water and catch them in midair. Reproduction Common dolphins are viviparous, as are all mammals except monotremes. Females normally give birth to one baby at a time, but have been found to carry twins or triplets. Gestation usually lasts 10 to 12 months.
Babies immediately become a part of the family group.
The calf stays close to its mother and never wanders more than a few feet away. The calf feeds on milk from the teats of its mother. Unlike human babies, however, dolphins do not have the lips needed to suck the teats. Also they could not breathe under water if they were able to suck. To solve these problems, the mother squirts milk into her offspring's mouth by contracting muscles.