IIRC some sharks grow up in their mom's belly and the first born will eat all its smaller siblings, egg or hatched, for nutrients. Also crustaceans react to dead bodies of their kind by engaging in a feeding frenzy unlike crows who react by cawing to warn others of a potential predator in the area. Animals just don't really share our values when it comes to corpses of our kind.
Also totally off topic but google "Siege of Suiyang"