Horseshoe crabs are popular for use as sand sifters. They spend most of their time bulldozing around in the sand just under the surface.They do come out of the sand occasionally and swim around the tank, but they prefer to be buried. They feed on detritus in the sand and on top of the sand, and will eat food that is presented to them, but I doubt they actually see the food. As far as I can tell, they don’t bother any other critters in the tank and nothing much seems to bother them. If you have carpet anemones you may want to
hold off buying these crabs because they will occasionally swim around in the tank and if they land on a carpet anemone, they will probably get eaten. The average size we sell is about 1. to 1.5″ in diameter, and although they can get real big in the wild, I doubt they will grow much more than 3″ in a home aquarium. The long tail on the horseshoe crabs is not poisonous, and the legs and small claws on the underside of the crab will not pinch you, so they are safe to handle.