|Scorpions - everyone's favourite!|
|In normal light...|
|And fluorescing under ultra-violet|
I'm not sure all the details are quite worked out yet, but I can see that there's some sense to this, and it's the best answer I've seen yet!
|Eight legs in a circle are perfect for vibration detection|
And the other useful trick they have for helping hunt is a phenomenal ability to sense and locate vibrations. As you have no doubt noticed, it's possible for us to hear something and look in the right direction to see what caused it - we do that by measuring the difference in time it takes for the sound waves to reach our left and right ears, but we're not very good at it really. Owls have perfected the ability and can use these aural queues alone to hunt in total darkness. But for scorpions it's the legs that do the job - and they've got eight to use to give extremely precise distance and direction sensitivity. It's estimated that using very sensitive hairs on the legs they can pick up a vibration of less than one millionth of a millimetre and use the difference in timing it takes for a vibration to travel from one leg to another to pinpoint the source so they can turn and run exactly the right distance and direction to catch their prey, despite very poor vision. Now that is truly awesome!
Gaffin, D., Bumm, L., Taylor, M., Popokina, N., & Mann, S. (2012). Scorpion fluorescence and reaction to light Animal Behaviour, 83 (2), 429-436 DOI: 10.1016/j.anbehav.2011.11.014