Always have a camera ready by the tank...
Last night as I was watching TV, there was some very loud "whacking" and I could see a blur of movement across the front of the tank.
It seems that one of the mantis found a crab and was in pursuit. I managed to snap a couple of photos of the brief battle, which was front/centre of the tank out on the open sand. The crab withstood only 3 blows. The mantis then grabbed his prey up and swam away back to his favourite hole.
Now I know what their primary food is. (This might be a good time to mention that I've also allowed the dozens of gorilla and other crabs to stay in the tank along with the mantis)
At the end, I shot a quick video. Unfortunately since the Sopranos was on TV, the background audio portion of the video is...well...not postable here....
__________________
400 gal reef. Established April, 2007. 3 Sequence Dart, RM12-4 skimmer, 2 x OM4Ways, Yellow Tang, Maroon Clown (pair), Blonde Naso Tang, Vlamingi Tang, Foxface Rabbit, Unicorn Tang, 2 Pakistani Butterflies and a few coral gobies
My Tank:
http://www.canreef.com/vbulletin/showthread.php?t=28436