About the offspring of Orcas
by firmm Team
Text: Brigitte, Photos: firmm
On the 6th of August we had enough time to observe the female Orca Lucia and her two cubs: Lucia caught a tuna, which she passed on to her daughter Estrella, who is about 3 years old. She, in turn, was probably instructed to show little Manuela, who is apparently only a few months old, how to eat tuna. It was wonderful to observe how Estrella actively dedicated herself to this task. In the month of August, we saw 4-5 adult Orcas with three calves (including Estrella) and a newborn (Manuela) on numerous trips.
Orca females become sexually mature at about 13 years of age. They have a calf every 3-12 years and nurse it for up to 18 months. Orca mothers have two milk teats hidden in skin folds. If the baby touches the teats with its mouth, milk is squeezed out. The milk has a very high fat content so that it does not dissolve in water. From the 18th month on, the little Orca starts to catch its own prey. It is still assisted, and the adults share their prey with it, or sometimes help by bringing live prey to the offspring.
The little ones keep their mothers constantly on the go in the first few months. Whale babies hardly sleep in the first month after birth, and so their mothers can’t either. Scientists at the University of California write that, surprisingly, the calves do not seem to need sleep for their development. Only after about half a year do the young animals rest for about as long as adult Orcas, which is about five to eight hours a day. For their mothers, this is certainly an exhausting time. For the young ones, however, this phase without sleep is very important for various reasons: they have to surface more often to breathe in; they are not so easily attacked by predators; the movement helps them to maintain their body temperature until they have developed the blubber, the layer of fat which is several centimetres thick.
Between mothers and their offspring exists a very close relationship. Researchers have often observed that mothers did not want to part with their dead young. One Orca mother in Canada didn’t let go of her baby for 17 days and carried it with her to keep it from sinking into the sea.
Orca groups are matriarchal. There is the female leader together with her offspring. The sons stay together with the mother all their lives. They only leave the group to mate and then return. Their offspring grow up accordingly in another group. The calves of the daughters remain in the group and are cared for by the females together. Other female Orcas also often play "babysitter". The babies learn from the adult whales by observing and imitating them. The knowledge is passed on from generation to generation. The whole group benefits from the experience and knowledge of the older females. They play important roles in foraging, know the best hunting grounds. Orcas around the world have different behaviours, prey and hunting methods. Grandmothers play an important role in passing on this complex culture. Female Orcas become infertile at around 40 years of age but live up to 90 years. Research teams from various universities in England suggest that Orcas have the longest non-human menopause. But why? The researchers think that the older ones probably succumb to their daughters and granddaughters in the reproductive competition and therefore go into menopause. If they no longer have offspring of their own, they can take care of their daughters' offspring and help provide them with food. This seems to be a significant contribution to the reproductive success of the species.