Spiders exhibit diverse and often surprising reproductive behaviors. While the idea of spiderlings consuming their mother may seem unusual, this act, known as matriphagy, is a strategy some species employ.
Matriphagy in Spiders
In some spider species, the young consume their mother, a behavior scientifically termed “matriphagy,” which translates to “mother-eating.” This process typically unfolds within the first few weeks after the spiderlings hatch. The mother often facilitates this consumption, sometimes allowing or encouraging her offspring to feed on her body. This act provides a direct and substantial nutritional source for the developing spiderlings.
Survival Benefits of Matriphagy
Consuming the mother provides significant evolutionary advantages for the spiderlings, contributing to their survival and development. This direct intake of maternal tissues offers a rich, immediate source of nutrients, leading to several benefits for the offspring. Spiderlings that engage in matriphagy often exhibit higher weights, faster molting times, and a larger body mass at the point of dispersal.
This enhanced nutritional start can also result in increased survival rates and the ability to capture larger prey items once they become independent. The mother’s self-sacrifice maximizes her reproductive success by ensuring the survival of her genes through stronger, better-equipped offspring. This behavior can also reduce competition among siblings for external food sources, as the mother’s body provides an abundant initial meal.
In some cases, such as with African social spiders, the mother actively invites her offspring to consume her, signaling her readiness through vibrations, which mimics a trapped insect. This final act of parental investment ensures the next generation has the best possible start in life, even at the cost of the mother’s own life.
Examples of Matriphagous Spiders
Matriphagy is observed across various spider species. The desert spider, Stegodyphus lineatus, is a well-documented example where the mother initially feeds her young by regurgitating bodily fluids. After one to two weeks, the spiderlings consume her entire body, leaving an empty exoskeleton.
The black lace-weaver (Amaurobius ferox) also practices matriphagy; the mother lays trophic (nutritional) eggs before signaling readiness for consumption via web vibrations. The crab spider Australomisidia ergandros employs a gradual process; its offspring consume the mother’s liquefied nutrients, or hemolymph, through her leg joints, causing her to shrink and become immobile. African social spiders (Stegodyphus dumicola and Stegodyphus mimosarum) are known for this behavior, with entire colonies consuming their mothers and other elderly relatives.
Variations in Spider Parental Care
While matriphagy represents an extreme form of parental investment, spiders employ many diverse strategies to ensure offspring survival. Many species exhibit different forms of parental care, ranging from simple egg protection to more involved provisioning. Some mothers guard their egg sacs until spiderlings emerge, protecting them from predators and environmental threats.
Other species carry their egg sacs, like wolf spiders who attach them to their spinnerets, or cellar spiders who carry them in their jaws. Once spiderlings hatch, some mothers continue care by carrying them on their backs or provisioning them with captured food. These varied approaches highlight spider adaptability, with each strategy maximizing reproductive success.