Deep-water decapod (Sergestes larva, decapod crustacean). The larval crayfish of the genus Sergestes has finely branched antennae that allow it to float in the free water column. Adult Sergestes crayfish are able to prevent shadows from being cast in the twilight by means of weak bioluminescence (self-produced light) on the underside of their bodies, thus camouflaging themselves from predators lurking below. The intensity of their glow is adapted to the current amount of light coming from above.