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Sponges (Chapter 26.2). Please set up your notebook for Cornell Notes. Phylum Porifera pore bearers Sponge characteristics Sessile spend entire adult life attached in a single place Multicellular with a few specialized cells Heterotrophic with no cell walls. Form and function
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Sponges (Chapter 26.2) Please set up your notebook for Cornell Notes
Phylum Porifera pore bearers • Sponge characteristics • Sessile spend entire adult life attached in a single place • Multicellular with a few specialized cells • Heterotrophic with no cell walls
Form and function • Body plan asymmetrical • Large central cavity • Choanocytes cells that use flagella to move water through the sponge • Osculum 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 structures • Spicule a spike shaped structure made of silica or calcium carbonate • Spicules are made by cells called archaeocytes • Sponges 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
Reproduction • Sexual sperm is released into the water and drawn into other sponges by the choanocytes • Fertilization is internal • Zygote 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 organism • Gemmules a group of archaeocytes surrounded by spicules • Can withstand extreme temperatures and drought
Why are sponges important? • Provide habitats for marine animals • Form partnerships with algae and bacteria • Spicules can direct light for photosynthesis even in dim water