Eva Crossan of Stirling asks :-

What animal wags its tail the fastest?

Ngaio Beausoleil, Vaughan Seed, and Christine Thomson, of the Institute of Veterinary, Biomedical and Animal Sciences, Massey University, responded.

The word ‘wag’ means a rocking movement of the tail. But which animal is the fastest tail wagger? Is it the dog saying ‘I’m happy to see you’, or the swordfish which by using tail movement for propulsion, can reach a top speed of 120 km/hr? Or is it the duck wagging its tail to attract attention of other ducks, before it sends them an important message? Perhaps the horse is the winner when it swishes its tail to brush away flies. Or is it the hippopotamus, which wags its tails to spread faeces and mark its territory.

Maybe the fastest tail wag belongs to the lobster, which when faced with a threatening situation, curls its tail under its body, propelling it backwards in less than 1/200th of a second.

Other animals move their tails rapidly to issue a threat, (beavers slap their tails on the water) to solicit a mate (male armadillos and hummingbirds) or to give information about the sender’s social, sexual or emotional status (dogs).

However, despite extensive searching, we could not find any scientific papers comparing the speed at which various animals wag their tails. Perhaps you can do a mini-study to work out which dog wags its tail the fastest? You may need to distinguish whether you wish to have the maximum speed at which the end of the tail is moving or do you want to study the shortest time of one oscillation of the tail.