The legs are more adapted for swimming than walking and each has two branches. There is a long abdomen ending in a tail fan which stabilises the animal while it is swimming. The tail fan has a pair of statocysts, cavities containing a floating particle and acting as a balancing organ in much the way the cochlea does in the human ear. The young which hatch from it are miniatures of the adults. Ecology Opossum shrimps are active swimmers, swarming just above the sea-floor.
Most species are quite translucent except for small black chromatophores and the pair of black eyes.
Distribution Mysids in Australia are exclusively marine but freshwater species exist in North America. Many species can be seen in shallow water, especially among seagrass beds, but only three are photographed here.