A cellar spider carrying her eggs - some of which seem to be fully formed.

A good question. Cellar spiders [Pholcus phalangioides] do exhibit some cannibalistic behavior, but eating their mothers is not typical. Instead, these spiders are known to be opportunistic predators, often feeding on a variety of small insects and other spiders. Cannibalism among siblings can occur, particularly if food is scarce, but the specific behavior of spiderlings consuming their mother is not characteristic of this species.