i'm reading Cannibalism: A Perfectly Natural History right now. my own notes, so take with a grain of salt, some fava beans and a nice chianti.

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A N I M A L S ('conspecifics' = animals of the same species)

reasons:

• not recognising their conspecifics
• stressful environments, incl. lack of other food
• prioritizing fewer but strong over more but weaker offspring

types:

• filial cannibalism (eating one's own offspring)
  • producing eggs just for food (insects, fish)
  • eating eggs for food because there's so many anyway (fish)
  • eating eggs as food while protecting the eggs (fish)
• heterocannibalism (eating unrelated conspecifics)
• sibling cannibalism
  • in-utero ('intrauterine') (sand tiger sharks)
  • oophagy (eating siblings who are still in eggs)
  • sacrificing one offspring to feed the others (birds?)
• sacrificing oneself as food for one's young (black lace-weaver spider)
• sexual cannibalism (of the smaller partner, which in invertebrates is mostly the male)

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wip!

what is and isn't cannibalism depends on your definition. is scavenging cannibalism? is eating your placenta? breastfeeding? chewing your nails?