@Profit5500, most people are not bitten by a crab. The crab has strong pinchers at the end of its claw-arms, and they grab you with the pinchers. Since it is a tight pinch, and hard to get them to let go again, even a small crab pinching you is quite painful. I have never tried the crab cages, but on the Washington coast; people fish for crabs this way, and I have seen the crab pots with crabs in them that other people have caught.
I have had crabs bite on my bait when I was ocean-fishing from the dock; but as I got them to the top of the water, they dropped off before I could get the fish net over the crab. When we had our cafe in Idaho, we served fresh craw fish, which my husband would order live, and then cook. I usually kept a few of the largest and friskiest ones for people to look at, and sometimes we would take one out and let it walk around on the table, which always made the kids squeal and scream.