Are there any ticklish animals?

We all know that most humans are ticklish; stroke their feet, underarms or behind the knees and you'll see squirming, laughter and movement. But are there any animals that are ticklish too, and can you tickle animals and see a similar response? And why are animals ticklish anyway?

Why are humans and some animals ticklish?

Ticklishness is a strange mixture of pleasure and pain – indeed, pain receptors in the skin are heavily involved in the sensation. The function – if there is one – is far from clear. One possibility is that it is a form of play-fighting between mutually trusting individuals.

Do animals laugh when being tickled? 

All of the great apes – orangutans, gorillas, chimpanzees and bonobos – respond to being tickled with a remarkably human-like laugh. Dogs, meerkats, penguins and many others also seem to enjoy it.

Rats giggle ultrasonically when tickled by humans but just like humans, they need to be in the right mood for it. In a relaxed setting, they will solicit the attentions of a tickler, but avoid it when they are anxious.

The fact that tickling is spread across so many different types of animal suggests that ticklishness may have ancient evolutionary roots.