Octopuses throw objects at one another, researchers observe

Scientists suggest octopuses propel material as part of den cleaning, but also in interactions and with purpose

They hunt alone, are prone to a scrap, and even cannibalise one another. And octopuses appear to have another antisocial arm to their behaviour: they hurl jet-propelled clouds of silt, algae and even shells.

Researchers studying Octopus tetricus, the common Sydney octopus, have filmed the cephalopods gathering debris in their front arms and web and jet-propelling it away from their body using water ejected from their siphon - the latter having been shifted between their rear arms for the purpose.