Franco Andreone, Wikimedia Commons // CC BY-SA 2.5

There are many animal moms that go above and beyond to give their children a leg (or wing or fin or tentacle) up in the world. A few mothers take that devotion to their family to a grisly extreme and allow themselves to become baby food.  

Among these are the caecilians, a group of wormlike, legless amphibians that live underground in the tropics. Some species give birth to live young, while others are hatched from eggs. In both groups, there are babies that come into the world with a set of blunt teeth built for scraping, which they put to use on their mothers. Scientists have found three different species where young caecilians get their first meal by stripping the skin off of their mothers’ backs with these specialized baby teeth. 

Shortly after they’re born, the little caecillians wriggle over mom and use their jaws to peel off a layer of fatty, nutrient-rich flesh. She doesn’t appear to mind, though. The scientists who discovered the flesh-eating behavior says the mothers stay pretty calm while they’re being flayed and don’t suffer any permanent harm—once the outer layer of skin is devoured, another takes its place. 

Other animal moms don’t have it so easy, and give a little bit more of themselves to their kids. Several spiders practice matriphagy and consume their mothers, which entomologist Mor Salomon—in wonderfully scientific deadpan—calls “an extreme form of maternal investment and an irreversible dead-end for the mother that precludes the possibility of future reproduction.”

One of these spiders is Stegodyphus lineatus, found in the Mediterranean and Middle East. Once a female’s 80 or so eggs hatch, she stops tending her web and eating, and devotes all her time to feeding her newborns. She pukes up a fluid made from what’s left of her last few meals and some of her own guts, which started breaking down while she guarded the eggs and built up as liquefied tissue in her abdomen. 

As the days go on and the spiderlings eat, mom’s innards continue to liquefy, and more of her guts and other organs like the ovaries dissolve as they become expendable. A little less than half of her body mass gets turned into food like this. 

After two weeks, mom has fed the children what she can and the well runs dry. The spiderlings then pierce her abdomen with their mouthparts and drain her of the rest of her body fluids. They’ll spend another two weeks at the nest with mom’s empty exoskeleton before going their own way. 

This kind of suicidal child care seems like a lot to ask, even of a devoted mother. Amazingly, though, there are some spiders that will serve themselves up as a meal even to kids that aren’t their own. A related species, Stegodyphus dumicola, is social and practices cooperative breeding. Females who don’t reproduce will help breeding spiders guard their eggs, feed their children through regurgitation and eventually allow themselves to be consumed.