The Mole Crab or Sand Bug Emerita talpoida lives on ( or rather in ) ocean beaches, burrowing in the surf zone, and at times free swimming. It is totally harmless and grows to 1.5". These odd and somewhat comical little creatures seem to do everything in reverse - they dig backwards, walk backwards, and swim backwards. Fishermen dig them up for bait.
Sand Bugs filter feed with their long feathery antennas, which are withdrawn into protective sheaths when not in use. Not the long eye stalks that allow the animal to remain completely buried, and the short powerful limbs. They are unable to walk in any conventional sense, but are powerful diggers, and also surprisingly swift ( if somewhat random ) swimmers.
Here is an assortment of large sharks that can be found in New Jersey waters, by no means all of them. These are more likely to be found offshore in oceanic waters. Sharks are seldom a danger to divers, they seem to be put off by the noise and bubbles. Nonetheless, all should be treated with caution.
Realistically, sharks in our waters are not a great concern. In over 350 northeast ocean dives, I have seen sharks on only several occasions ( not counting harmless little Dogfishes ) and only once while in the water. That one was in the Mud Hole, on the Arundo, to be precise. It was a Blue, or possibly a Mako, and wanted nothing to do with me, which was a relief since I had half an hour of deco left to do at the time! That would have left me very bent otherwise.
Note the difference between the toothless Basking Shark at left and the very not toothless Great White Shark at right.
If you think about it, humans must taste terrible to sharks, and scuba divers especially - with rubber suits and big metal tanks. Many shark attacks occur in murky water where the shark is not sure what it is attacking. Some attacks have been the result of the shark being stepped on in shallow water. Most shark attacks on humans are abortive, the shark taking only one exploratory bite, then realizing its mistake and breaking off the attack. Unfortunately, with a large shark, one bite and you're dead. Many predators, from bears to tigers, will prey on humans when sickness, injury, or old age make them unable to catch their normal prey. Sharks are probably no different.
