1. II. Phylum Porifera : Sponges
*Sponges are the simplest, most
ancient animals. Porifera means,
“pore bearers”.
A. Characteristics of Sponges
1. Contain pores (holes) to get food.
2. Adults are sessile (don’t move).
3. Are filter feeders – move water
containing food in their pores & out a large hole in the top (an Osculum).
4. Body is asymmetrical & sac-like.

2. Characteristics of Sponges con’t.
5. Are multicellular.
6. Are heterotrophic, have no cell walls, & contain few specialized cells.
7. Have no mouth, gut, specialized tissues, or organs.
8. Have skeletons.
9. Reproduce sexually or asexually.

3. B. Structure of sponges -Sponges have a simple body form.
-They depend on a current
of water for everything,
since they’re sessile.
-Body forms a wall around
a center cavity. Wall
contains pores, to
allow water flow into
the center cavity.

4. Special cells & structures
1. Collar cells (Choanocytes) – digest food particles & contain flagella that move the water current through the sponge.
2. Osculum – large hole in the top of the sponge that allows water to exit the central cavity.
3. Spicule – thin, spiny structures that form the simple skeleton.
4. Amebocytes (Archaeocytes) – cells that build spicules, digest food, & transport particles to cells.
5. Spongin – fibers of protein that make up softer sponges.

5. C. Reproduction in Sponges
1. Sexual reproduction – eggs are stored inside the walls of female sponges. Male sponges release sperm into the water.
-Sperm enter the female
sponge through the water
current & her cells carry
the sperm to the eggs to
be fertilized (internal
fertilization).
-Some are hermaphrodites.

6. Asexual Reproduction in sponges
2. Asexual reproduction – is either budding or regeneration.
Gemmules – sphere shaped
collections of amebocytes
surrounded by a tough
layer of spicules.
-Can survive harsh
conditions & later grow
into new sponges.