Leucosolenia – a simple sponge

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Leucosolenia(fig. 7-1) is a simple sponge, white or yellowish in color, which cosists of long, narrow tubes that project upward from connecting horizontal tubes. The upringht tubes have an opening (osculum) at the top; the inside of the tube is the central cavioty or spongocoel. The body wall consists of an outer epidermis (dermal epithelium) of thin, flat cells and an inner lining of undulipodial collor cell (choanocytes), the choanocytes are in loose contact wityh each other and create a current of water though constan undulipodial (flagellar) beating.

          Between the two layers of the body wall is a gelatinous mesoglea containing various amoeboid wandering cells (amoebocytes), which give rise to reprodutive and several types of somatic cells, including those for pigment and food storage. Many three-pronged (triradiate) spicules are interlaced in the soft tissues of the body wall, serving to strengthen the body and hold it upright.

A collored dye placed in the water will be drawn into the leucosolenia through minute incurrent pores in the body wall and pass out through the osculum (an exhalant opening). Sponges are the only animals in which the large opening serves as an exit, rather than An entrance, for water.