Because dolphins take so long to mature, the mother and calf develop a close bond in order for the young to survive.
Dolphins live for several decades and take a long time to mature, requiring close parental care for the first few years. As soon as the calf is born it’s helped to the surface by another dolphin in order to takes its first breath and within minutes it’s swimming and breathing on its own. Calves are born with a flexible pectoral fin and flukes and aren’t strong enough to keep up with the pod as it moves. To ensure the calf doesn’t get left behind, it remains close to its mother, travelling in her slipstream.
Initially, like other mammals, calves gain nutrition from milk produced by their mother. This is around 33% fat, which helps the calf to develop a layer of blubber for insulation. Feeding underwater is challenging and a dolphin’s nipples are concealed behind mammary slits on its abdomen in order to maintain hydrodynamics. However, the mother is also able to actively squirt milk to her young. The calf begins feeding in the first 6 hours after birth, sessions are short so the calf feeds frequently, remaining close to its mother at all times. At around 4 months old, the infants teeth will start to grow, enabling it to begin eating fish, however, it continues to suckle for another 6 to 18 months. The mother and calf have a strong bond and even after weaning the 2 remain close for an average of 3 to 6 years. In some populations baby-sitting has been observed and if a mother need to leave the group to find food, another dolphin will take care of her calf. When they reach maturity, male dolphins often leave their family pod to travel alone or in small bachelor groups, while females often stay with their original family group.