The flexibility of these layers and re-modeling of the mesohyl by lophocytes allow the animals to adjust their shapes throughout their lives to take maximum advantage of local water currents. Sponges can control the water flow by various combinations of wholly or partially closing the osculum and ostia (the intake pores) and varying the beat of the flagella, and may shut it down if there is a lot of sand or silt in the water.Īlthough the layers of pinacocytes and choanocytes resemble the epithelia of more complex animals, they are not bound tightly by cell-to-cell connections or a basal lamina (thin fibrous sheet underneath). Since ambient currents are faster at the top, the suction effect that they produce does some of the work for free. Most sponges work rather like chimneys: they take in water at the bottom and eject it from the osculum ("little mouth") at the top. Water Flow and Body Structures Asconoid Syconoid Leuconoid Pinacocytes Choanocytes Mesohyl Water flow
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