All in the Family: Why certain species cannibalise on their own

Other bird species, who indulge in this include egrets, blue-footed boobies and laughing kookaburras. Parent birds sometimes deliberately lay eggs in a staggered manner as an insurance policy – so that at least one chick in the clutch survives.

Group of seagulls perched on a rocky surface near the sea. (Source: Freepik)

A lovely pearl white crab spider, I was observing several years ago, on a kumquat bush fiercely guarded her egg case and cleverly ducked behind leaves when it rained. Eventually, the baby spiderlings emerged – tiny white specks scuttling up and down fine threads of silk. Up in the still crowded egg case, there was mayhem, as the spiderlings commenced dining on each other; there is one species of spider where, when food is short, the mother sacrifices her body to her progeny so that they can survive. Not the kind of family life one would like to have surely but a ticket to survival for the young.

But this was like a fairy tale when compared to what goes on in the paired uteri of the sand tiger shark. Here, the first embryos to be hatched in each of the uteri would cannibalise their sibling embryos once they reached a particular size in the uterus. It cut the competition and made them strong when they emerged in their shark-eat-shark world.

Spotted hyenas too have a pretty unpleasant family set up, where the eldest female bullies and bites her younger sisters into submission, or even kills them. Hyena clans are ruled by females and a male, no matter how ‘well born’, is kept at the bottom of the social hierarchy. The rationale is the survival of the fittest, especially when food is short and the parents are hard-pressed to feed a brood. In these conditions only the strongest (usually the first born) gets to eat; the others get eaten.

Fortunately, there are many happy and stable families in the animal kingdom too, where again, the rationale is survival. Elephants live in herds led by a wise old matriarch and her sisters, daughters and grand-daughters, having booted out their boorish teenage sons from the herd as soon as they turn obstreperous. Even when herds split up, separated family members will warmly meet and greet each other at waterholes, where they might gather to drink and bathe. Lions live in prides, where the ladies rule the roost (sisters usually) and will even suckle each other’s cubs which, of course, have a ball living together in one large rambunctious joint family. Shaggy-haired males in charge of security, territory, (and occasionally bringing a buffalo or elephant down) are usually brothers-in-arms and will form formidable (and affectionate) partnerships. Cheetahs too are famous for the coalitions they form – again a band of brothers, perhaps three or four strong – which make the hunting so much easier.

Wolves and African wild dogs live in family packs, led by an alpha pair, the only ones allowed to breed. The other members of the pack – usually related – help in bringing up and feeding the pups, (babysitting them if necessary) and hunting down prey, which is why African wild dogs, for example, have among the highest successful kill rate among predators. By itself, a wild dog could not, for example, take down a wildebeest but a pack of half-a-dozen easily could.

A rambunctious family life is vital for many species – the rough and tumble we see among lion cubs for instance, is not just play but training in stalking, pouncing and wrestling – in developing hunting techniques and skills so essential for survival. Even insects live in large families – the bees in a hive are sisters, and will work to keep the hive and larvae clean, cool, well-fed and defended from predators.

When it comes to choosing a queen, however, family life can become quite nasty. When the existing queen dies or abdicates (to form another hive elsewhere), special ‘princess’ larvae, brought up on extra-large helpings of royal jelly, will struggle to get out of their special cells, the one succeeding (and heiress to the throne) mercilessly killing all the other wannabe queens still in their cells. Furthermore, she will spread a special pheromone that will render all her sister bees disinterested in the handsome drones that hang around the hive, wanting to make out. Now that is a mean trick to pull, no matter what species you belong to.