Watch: Whales 'kelping' off the eastern coast of the US
Whales enjoy throwing seaweed on their heads and holding it in their mouths as makeshift toothbrushes, new research from Australia suggests.
Scientists examined the behaviour - called kelping - by analysing aerial footage and social media posts of more than 160 whale interactions.
They found it may also be used to scrub off parasites and rub away dead skin.
The study has labelled the findings a "global phenomenon".
Drone footage captured a whale playing in a patch of seaweed off the eastern coast of the US.
