The Phylum Porifera is the simplest of the multi-celled animals. The color
of sponges as well as their shapes vary considerably, depending on the
different growing conditions in which they live. There are three classes
of sponges: Calcarea, Hexactinellida and Demospongiae. A sponge is a group
of individual cells, each with a specific function, working cooperatively.
The cells organize into a system of canals, chambers and pores through
which water is carried. Most sponges have a skeleton that is a meshwork
of spicules, but an accumulation of organic fibers may be present also.
Spicules can be made up of either calcium carbonate or silica. Water enters
the canals through the minute pores called ostia which cover the surface
of the sponge. The inside of the canals are lined with collar cells which
contain a hair-like structure called a flagellum, whose beating action
creates a current. This current pumps water through the canals and out
of the sponge through the large pore, the osculum. The collar cells trap
particles of food and either digest them or send them to other cells to
be digested. The flowing water brings oxygen to the sponge and removes
carbon dioxide and other waste products.
The Phylum Porifera is the simplest of the multi-celled animals. The color
of sponges as well as their shapes vary considerably, depending on the
different growing conditions in which they live. There are three classes
of sponges: Calcarea, Hexactinellida and Demospongiae. A sponge is a group
of individual cells, each with a specific function, working cooperatively.
The cells organize into a system of canals, chambers and pores through
which water is carried. Most sponges have a skeleton that is a meshwork
of spicules, but an accumulation of organic fibers may be present also.
Spicules can be made up of either calcium carbonate or silica. Water enters
the canals through the minute pores called ostia which cover the surface
of the sponge. The inside of the canals are lined with collar cells which
contain a hair-like structure called a flagellum, whose beating action
creates a current. This current pumps water through the canals and out
of the sponge through the large pore, the osculum. The collar cells trap
particles of food and either digest them or send them to other cells to
be digested. The flowing water brings oxygen to the sponge and removes
carbon dioxide and other waste products.