Whoever is writing the parenting books for Stegodyphus lineatus spiders should probably consider a career change. We’re all for dedicated mothering, but these arachnids are taking things a bit far (and making the hard work of mothers everywhere look insufficient). I imagine an excerpt from such a parenting book would go something like this:
A balanced diet is essential, regular servings of vomit will help your spiderlings grow up healthy and strong (if you’re the affectionate type, throw up on your face and watch your little angels jostle for a spot at the feeding!). But remember: face-vomit is not enough – allow your babies to pierce your abdomen and supplement their diet with a tasty blend of your own innards. Protein is vital.
A study published in the April Journal of Arachnology explains how the bodies of Stegodyphus lineatus moms slowly break down to become a nutritious meal to satisfy the voracious appetites of her young. The spiderlings begin their lives encased in what looks like a mini silk hockey puck at one end of the web. Mama spider fills the puck with about 80 yellowish eggs that she entombs in a spider-sized cave. When they hatch, she pierces the silk to set them free (although perhaps if she knew what she was in for, she’d leave them in there). After releasing her spawn she stops eating … for the rest of her life. Over the next two weeks or so, the doting mom regurgitates a transparent liquid made up of her final meals, mixed with a bit of her own guts for good measure.
And just to make things a touch weirder, she doesn’t politely regurgitate a meal at the spider dining-room table. Oh no. Instead, she lets the life-giving liquid spew out onto her face, turning her visage into an all-you-can-eat buffet for the pale-coloured youngsters (dining etiquette is not a big deal in spider circles).
While mama spider will regurgitate about 41 percent of her body mass to feed her hungry progeny, face vomit doesn’t quite fill the gap for the growing spiderlings ... so possibly at mom’s invitation, the babies take things a step further by piercing her abdomen and draining her innards over the course of a few hours. “She makes no attempt to escape,” says the study's author Mor Salomon.
Early on in the feeding “if you touch a leg, she will pull it back … she’s definitely alive,” says Salomon. But motherhood in this instance is fatal, and by the end of the ordeal the spider mom dies, leaving behind a measly five percent of her original body mass. Organs are dissolved in a systematic fashion as they become expendable. Her babies are a bit like tiny serial killers, strategically keeping their victim alive right until the bitter end. You go, little Hannibals.
Extreme maternal care like this is not uncommon – regurgitation and matriphagy (munching on mom) has been recorded in all spiders in the Eresidae family studied to date. According to another study by Salomon and Lubin, Stegodyphus dumicola hatchlings even chow down on non-breeding females, turning them into sacrificial aunts that help the little spiderlings on their way.
But what makes Stegodyphus lineatus moms extra special is that they begin preparing their morbid ‘baby formula’ before their eggs even hatch. The new study shows that the spider’s midgut starts breaking down while she guards her prospective brood, so by the time the youngsters burst forth from their silky hockey puck, she’s already packing a liquefied gut suitable for baby spider mouthparts. For the next two weeks, her body continues to break down in preparation for the ultimate sacrifice.
“This is the first demonstration of the mechanism underlying suicidal maternal care in an arthropod,” according to the study.
In a poetic twist, mom’s heart lasts right until the end. Talk about an apt metaphor for motherhood: she sacrifices nearly everything, leaving only her heart behind. You can’t make this stuff up.
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