There are several crustacean forms that are commonly called shrimp although they do not belong to the same order as the true shrimp, order Decapoda, which also includes the lobsters and crabs. Mysid shrimp are not true shrimps, although they look very similar. Mysid shrimp (Mysis littoralis) are members of the order Mysidacea. Often called opossum shrimps because they carry their young in an under-belly pouch, they are smaller in size than the true shrimp.
With their distinct set of antennae, mysids can be easily confused with krill, another shrimp-like creature. Mysids, however, inhabit a different space in the water column. At most times of the year, they are found in shallow, intertidal waters with mud bottoms or granular sediments and seaweeds. Krill are found in deeper waters, from the surface down to depths of about 275 meters
Mysid shrimps can often be found behind clumps of seaweed, hiding from the current. They can be difficult to spot (look for the eyes), and monitoring them is hard – but rewarding – work!