Matriphagy

Matriphagy is the consumption of the mother by her offspring. The behavior generally takes place within the first few weeks of life and has been documented in some species of insects, nematode worms, pseudoscorpions, and other arachnids as well as in caecilian amphibians.

The specifics of how matriphagy occurs varies among different species. However, the process is best described in the Desert spider, Stegodyphus lineatus, where the mother harbors nutritional resources for her young through food consumption. The mother can regurgitate small portions of food for her growing offspring, but between 1–2 weeks after hatching the progeny capitalize on this food source by eating her alive. Typically, offspring only feed on their biological mother as opposed to other females in the population. In other arachnid species, matriphagy occurs after the ingestion of nutritional eggs known as trophic eggs (e.g. Black lace-weaver Amaurobius ferox, Crab spider Australomisidia ergandros). It involves different techniques for killing the mother, such as transfer of poison via biting and sucking to cause a quick death (e.g. Black lace-weaver) or continuous sucking of the hemolymph, resulting in a more gradual death (e.g. Crab spider). The behavior is less well described but follows a similar pattern in species such as the Hump earwig, pseudoscorpions, and caecilians.

Spiders that engage in matriphagy produce offspring with higher weights, shorter and earlier moulting time, larger body mass at dispersal, and higher survival rates than clutches deprived of matriphagy. In some species, matriphagous offspring were also more successful at capturing large prey items and had a higher survival rate at dispersal. These benefits to offspring outweigh the cost of survival to the mothers and help ensure that her genetic traits are passed to the next generation, thus perpetuating the behavior.

Overall, matriphagy is an extreme form of parental care but is highly related to extended care in the Funnel-web spider, parental investment in caecilians, and gerontophagy in social spiders. The uniqueness of this phenomenon has led to several expanded analogies in human culture and contributed to the pervasive fear of spiders throughout society.