3 November, 2018 - 08:00 (Research Matters)
Dolphins ‘see’ using sound, like bats. Each individual has a signature whistle that is unique to them, sort of like a name. They sleep with half their brain awake, and their eyes operate independently of each other. Oh, and they have an infanticidal streak.
Yes, despite their reputation for being playful, kind and peaceful creatures, bottlenose dolphins are also known to fatally injure newborn dolphin calves by ramming into them and flipping them out of the water. Though rare, there have been documented incidents of baby dolphins being attacked by males—a phenomenon observed even in other species like monkeys and lions.
The exact cause of this disturbing behaviour is not known, but it is thought to benefit those males who have not sired that particular offspring by reducing the female’s inter-birth period. After birth, mating does not occur as the female stops ovulating for the entire duration that her infant is dependent on her milk – a phenomenon known as lactational amenorrhea. Losing her calf prematurely brings her back into oestrus and makes her sexually receptive once again, which gives the males a chance at mating with her and siring their own offspring.
The mother protects the young one as much as she can, but is not always successful. A heart-wrenching sight usually observed after the deed, is the female carrying her dead or close-to-death calf near the surface of the water in an attempt to help it breathe.
This isn’t to say that dolphins are cruel, cold-hearted creatures—animals work on a different wavelength from humans. But, it makes you think of Flipper in a whole new light, doesn’t it?