Female Spiders Offer Themselves as Sacrificial Food for Spiderlings

Khryss | Published 2017-09-29 22:57

"Eat me!" says the sacrificial spider to the babies.

Now to challenge the Jon Snow-Khaleesi Targaryen bond, here's another weird incest-ish happening. Our topic for today: baby spiders sucking the life out of grown-up female spiders, literally. (Wait, is that cannibalism?)

Good-hearted velvet spider aunties dutifully take care of their sister's eggs and then regurgitate food for hatchlings. Right after that, they offer themselves to these baby spiders and provide the perfect nutrition from their own juices. And take note, these spiderlings may be small but they don't have mercy--they'll suck their loving aunties dry!

“[The] spiders literally start feeding on the female while she is alive,” says Trine Bilde at Aarhus University in Denmark. Baby spiders dissolve her internal organs by injecting enzymes and then slurp the semi-digested fluids, leaving her with just the outer shell. “But there is no apparent aggression. It looks as if females are almost inviting spiderlings to feed on them.”

S. dumicola is a species of social spiders. They live together in large communal nests, of which they all cooperate on doing different tasks like capturing their meal, defending their territory, and taking care of the babies.

Its closely related species S. lineatus is known for their "alloparenting" on which mated females take care of other spiderlings as well as their own. The act of mating itself seemed to have caused this. However, they offer themselves as dinner to their own spiderlings only, a behavior known as matriphagy.

But when S. dumicola virgin females were observed, they also apparently performed all forms of alloparenting just like the mated ones. When two mated and three virgin females, along with some spiderlings were placed in one place, all females did the deed: they tended the eggs, regurgitated food and then sacrificed themselves as meals.

“The investment in these offspring is an investment in her lifetime reproductive success,” says Bilde. “The more gene copies she propagates to the next generation, the better, so providing your body as food is a sensible evolutionary solution.”

Damn, that's one heck of "tradition" right there. Female virgin sacrifice; huh, never gets old.


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