Predominantly marine, but may enter freshwater. Adults occur inshore in intertidal waters, under stones and in pools on sheltered rocky shores with much weed cover. They feed on crustaceans (larger amphipods, isopods, small crabs) and polychaetes; juveniles eat harpacticoid copepods, amphipods, polychaetes and mites (Ref. 4696). Oviparous (Ref. 205). Fusiform shaped eggs are found in patches of several thousand on undersurface of stones, shells, polychaete tubes or Ciona mantles (Ref. 4696).