ECOLOGICAL DETERMINATION OF THE SETTLEMEN T OF HYDROZOAN PLANULAE

The study of Hydrozoan planulae settlement show that light, gravity an d the relief of a substrate determine planular movement to a settling site. Currents make planular dispersal while their velocity restrict p otential settling zones. Exposure to air during low tides induce or ac tivate planular attachment and metamorphosis of littoral hidroids. The complex of physical factors determine planular dispersal and settleme nt, influencing the processes of planular movements on substrate surfa ce as well as the selective settlement on specific substrata and final attachment.