Mantis Shrimp
Squilla empusa is a species of mantis shrimp found in areas of the western Atlantic Ocean from the Gulf of Mexico to Cape Cod, from the intertidal zone down to about 500 ft. It excavates and occupies a deep U-shaped burrow in soft sediment, from which it emerges, mainly at night, to feed on fish and invertebrate prey. They grow to a length of 12", although I have only ever seen small ones in the bellies of striped bass.
Squilla empusa is mainly nocturnal and feeds on fish, shrimps, crabs, krill, worms, molluscs and other mantis shrimps. The raptorial claws are unfolded with great rapidity to spear, slash and immobilise the prey, which is brought back inside the burrow when caught. Take care in handling them, even a small one can draw blood.
Mantis shrimps are not true shrimps, they are not even related.