Sponges (Chapter 26.2)Please set up your notebook for Cornell Notes

Phylum Porifera pore bearersSponge characteristics

Sessile spend entire adult life attached in a single placeMulticellular with a few specialized cellsHeterotrophic with no cell walls

Form and functionBody plan asymmetrical

Large central cavityChoanocytes cells that use flagella to move water through the spongeOsculum large opening at the top of sponge where water exits

This movement of water allows a sponge to feed, respire, excrete and circulate

Other cell structuresSpicule a spike shaped structure made of silica or calcium carbonate

Spicules are made by cells called archaeocytesSponges are filter feeders

Sift microscopic food from water and digest intracellularly

Sponges have no nervous tissue and cannot respond to changes in the environment

Some sponges do produce toxins to thwart predators

ReproductionSexual sperm is released into the water and drawn into other sponges by the choanocytes

Fertilization is internalZygote develops into a larva that is free floating and carried by water currents until it settles and attaches to a surface

Asexual Budding a new individual grows on the body of the parent and detaches forming a separate organismGemmules a group of archaeocytes surrounded by spicules

Can withstand extreme temperatures and drought

Why are sponges important?Provide habitats for marine animalsForm partnerships with algae and bacteriaSpicules can direct light for photosynthesis even in dim water