• Phylum Porifera

• Have tiny openings, or pores, all over their bodies

• Sessile: they live their entire life attached to a single spot

• They are animals! Why…?

• Multicellular

• Heterotrophic

• No cell walls

• Contain a few specialized cells

• Have nothing resembling a mouth or gut

• Have no tissues or organ systems

• Simple functions are carried out by a few specialized cells

• Have no front or back ends, no left and right sides

• A large, cylindrical water pump

• The body forms a wall around a large central cavity through which water flows continually

• Specialized cells that use flagella to move a steady current of water through the sponge

• Filters several thousand liters/day

• A large hole at the top of the sponge, through which water exits

• The movement of water provides a simple mechanism for feeding, respiration, circulation and excretion

• Spicule: • A spike-shaped

structure made of chalk-like calcium carbonate or glass-like silica in hard sponges

• Archaeocytes: • Specialized cells that

make spicules

• Filter feeders

• Sift microscopic food from the water

• Particles are engulfed by choanocytes that line the body cavity

• Rely on the movement of water through their bodies to carry out body functions

• As water moves through the cavity:

• Oxygen dissolved in the water diffuses into the surrounding cells.

• Carbon dioxide and other wastes diffuse into the water and are carried away.

• No nervous system

• Many sponges protect themselves by producing toxins that make them unpalatable or poisonous to potential predators

• Sexually or asexually

• A single spore forms both eggs and sperm; usually at different times

Internal Fertilization:

• Eggs are fertilized inside the sponge’s body

• Sperm are released from one sponge and carried by currents to the pores of another sponge.

• Budding

• Gemmules: Groups of archaeocytes surrounded by spicules

• Ideal habitats for marine animals such as snails, sea stars, sea cucumbers, and shrimp.

• Mutually beneficial relationships with bacteria, algae and plant-like protists.

• Many are green due to these organisms living in their tissues.

• Attached to the sea floor and may receive little sunlight.

• Some have spicules that look like cross-shaped antennae.

• Like a lens or magnifying glass, they focus and direct incoming sunlight.

Porifera – “pore bearers”

No true tissues (most primitive animals)

Free-swimming larvae; sessile adults

Filter-feeders

Flagella move water through pores in wall of sponge and out through the top

Food particles are filtered out as waster passes through

Harder sponges may contain calcium carbonate or silica spicules in their “skeletons”

Most are marine

Example: Sponges

Single opening

Pores

Pore

direction of water flow

Flagellate cells (inner layer)

Spicules

Epithelial cells (outer layer)