Nature
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Raising offspring is expensive. It costs you time, it costs you money, and for some species: it costs you your life. This is the grisly fate of the African social spider, Stegodyphus dumicola, a dedicated mother who can only become a mother once. Why? Because her babies will eat her.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.This is what’s known as matriphagy, a form of parental cannibalism that can occur before or after birth when the parent is already dead... or still alive. It’s mostly seen in invertebrates, but the African social spider is a particularly infamous example because of the way the mother actively invites her offspring to eat her.
Now, the entire process of matriphagy in African social spiders had been caught on camera for the first time, and features in a new series from BBC Factual and Sir David Attenborough: Parenthood. Documenting the highs and lows of raising offspring, the series dives into the incredible ways different species have adapted to ensure the next generation survives long enough to carry on their legacy (including crabs 'cloning' anemones so they always have two boxing gloves to protect their kids with). As bum deals go in parenting, however, matriphagy has got to be right up there.
African social spider babies aren’t especially scary to look at, at just a few millimeters long, but what they lack in size, they make up for in numbers. However, the female African social spider isn’t overcome by her offspring when the time comes to be dinner. Oh no, she offers herself up willingly.
As parenthood takes its toll, the mother spider becomes increasingly sluggish and her labored movements begin to shake the web she shares with her many hungry offspring. The movement mimics that of a trapped insect, and her babies descend on what they have come to learn signals dinner. This time, the dish of the day is their own mother, and they dine out on her tissues, bringing her short life to an end.
The babies won’t be on their own, however. As their name suggests, African social spiders live in groups, and only around 40 percent of the females will ever reproduce. The remaining “virgin females” are heavily involved in the parental care of their sisters’ offspring.
Wondering why (god, why)? Understandable, but the brutal approach to parenthood does appear to have some benefits. Matriphagy boosts the offspring's weight and means they don't have to cannibalize their siblings to survive, which is handy for a social species. Furthermore, some matriphagous offspring can take down bigger prey than hatchlings that don't eat their moms, so it may also make them better hunters. Must make for some awkward chats at the dinner table, but hey – it's one way to put food on the table.
Hungry for more curious approaches to parenting? Parenthood premieres on Sunday, August 3 at 7.20 pm BST on BBC One. All episodes will be available on BBC iPlayer.
