Like sharks, stingrays are able to sense electric signals produced by other living creatures, so are able to detect crustaceans burrowed into the sand and dig them out. This stingray had just about had enough of my presenence at this point. You can see how he's raised his body up off the sand and has his tail flared up behind him reminding me of the barb on its end. Stingrays only use these barbs in self-defence, but I didn't want to disturb him any further and so left him alone to return to his hunting.
