Playful whales can use seaweed as a hat – or exfoliant. This "kelping" behaviour is more common than we realised

WA Western Whale Watch Australia, CC BY-NC-ND

If you’re a whale, there’s often not too much to see out in deeper water. Perhaps that’s why so many whales get playful with kelp and other seaweed.

Once might have been chance. But we’ve collected over 100 examples on social media of whales playing with seaweed, known as “kelping”. It’s not just one species –  gray whales, southern and northern right whales, and humpback whales all do it.