LEUCOSOLENIA

also called Leucoselenia genus of tubular branched sponges of the class Calcispongiae (phylum Porifera). Found in tide pools and on wharves and represented by numerous species, the widespread genus includes most of the asconoids, structurally the simplest sponges. Most species of Leucosolenia are 2.5 centimetres (one inch) or less in length. They grow as a group of slender individuals connected by a common stoloni.e., a rootlike processwhich also attaches the group to the bottom or to some other surface. Waterwhich enters the central cavity (spongocoel) of the animal through numerous tiny perforationsis expelled through one large opening, the osculum, at the tip. The water current is created by flagella attached to the choanocytes, the cells that line the spongocoel. The outer body wall consists of thin, flat cells called pinacocytes. Between the two cell layers is a jellylike matrix, the mesoglea, which usually contains freely moving cells (amoebocytes) and skeletal spicules often shaped like slender three- or four-pointed stars. The spicules, which provide support for the body tube, are produced by special amoebocytes. New individuals usually develop as free-swimming flagellated larvae from eggs produced by amoebocytes. These larvae enter the spongocoel of the parent and then pass through the osculum, eventually attaching themselves permanently to a surface. Some leucosolenidsfor example, L. botryoidesalso may reproduce by budding, a process in which a fingerlike extension of the parent body breaks off. The tip of the extension becomes the lower end of the new individual when it attaches to a new site.