Porifea - Sponges
The Phylum Porifera is in the Kingdom Animalia. Porifera
means to bear pores and are commonly known as sponges. Most sponges
are marine with 5,000 to 10,000 spp. known. Sponges can not live
on land as they need water.
Sponges have no organs or tissue but rather are made up of
cells. They have a cellular level of organization. Every cell
serves a particular function. The amoebocyte cells are multifunctional.
They transport and store food. The skeleton of a sponge is made
up of Spicules (glass-like abrasive fibers similar in appearance
to fiberglass) and spongin.
Sponges are characterized by the feeding system unique among
animals. They have a choanocytes (collar cells) and pore cell
shaped like a cylinder. One long flagellum extends from each
choanocytes and directs the flow of water to and from the sponge.
Tiny pores (ostia) in their outer walls draw water into a cavity
called the spongocoel. The water exits through one or more larger
openings (oscula). Sponge cells perform a variety of bodily functions
and appear to be more independent of each other than are the
cells of other animals.
They are sessile creatures meaning they don't move once attached.
Sponges can reproduce both asexually and sexually producing both
sperm and eggs.
Asexual reproduction is accomplished by fragmentation. The
sponge is able to repair damage to itself. It has been said you
could take a sponge and blend it in a mixer and pour it out and
the sponge would be able to regenerate itself. One piece can
grow into a new sponge.
Many sponges are hermaphroditic meaning the can produce both
sperm and eggs. Larve are planktonic and can drift away to attach
somewhere else and grow into an adult sponge.