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Page 75. ABBOTTSCOLLEGE. Multicellular Heterotrophic Cells do not have cell walls Mainly reproduce sexually. Page 75. We must look at the relationship between their body Plans and modes of living We will start with the least advanced forms of aquatic life
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Page 75 ABBOTTSCOLLEGE
Multicellular • Heterotrophic • Cells do not have cell walls • Mainly reproduce sexually Page 75
We must look at the relationship between their body Plans and modes of living We will start with the least advanced forms of aquatic life And note the evolutionary progress up the phylogenic tree
Asymmetrical (have no symmetry) • Acoelomate (have no body cavity) • Have no tissue layers Bodies are a mass of cells embedded in a jelly-like Substance They function at the cellular level of organisation (meaning they have no tissues or organs)
Body is supported and protected by a skeleton of minute spicules (made of calcium, silica or a protein), bringing food to the cells
Collar cells (flagellated) line the interior cavity of the sponge and help to draw water through the cavity
Digestion takes place intracellularly (inside the cells) • Excretion and respiration occur by diffusion