A harlequin shrimp.  The shrimp has specialized arms with injectors

to inject paralyzing venom into its prey (starfish).

(Beang-a-bang, Pantar Island, Indonesia)

arthropod; crustacean; decapod; shrimp; harlequin shrimp; Arthropoda; subP Crustacea; Malacostraca; Decapoda; subOrder Pleocyemata; infraOrder Caridea; superFamily Palaemonidae; Hymenoceridae; Hymenocera elegans, South Pacific