Définition : Direct developers are characterized by young that resemble the adult form even in early stages of development. The larval stages of marine direct developers generally have very low dispersal potential.
Définition : Planktotrophic species generally have fairly long pelagic larval durations and feed while in the water column. Consequentially, they have the potential to disperse long distances.
Définition : Eye-spots which may be set into a pit to reduce the angles of light that enters, to allow the organism to deduce the angle of incoming light. Lens-like structures may be present, but stemmata, unlike lens eyes, cannot form an image, either for lack of refractive power or retinal resolution.
