In a species of marine isopods, males are polymorphic and exist in 3 forms, α, β, and γ of different sizes. Of the three, α males are the largest and most dominant; they mate with multiple females in a harem. The β males mimic the females and therefore manage to mate with some of the females in an α male’s harem. The γ form is much smaller and mimics the juvenile form, also allowing it to escape detection.