Leucosolenia – a simple sponge
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.
No comments