Meet blue-ringed octopuses, members of the genus Hapalochlaena. They inhabit coral reefs in the Indian and Pacific oceans. Though they usually measure less than 8 in (20. 3 cm) at their largest, keep your distance: Blue-ringed octopuses are among the world’s deadliest cephalopods. Their venomous bite can paralyze, and even kill, a human. Photo: imogenisunderwater, CC BY-NC 4.0, iNaturalist















