Respiration in Polyzoa (Ectoprocta)


THE accepted view that zooids of the Polyzoa (or Ectoprocta) are small enough for gaseous exchange to be achieved by diffusion has recently been challenged. Mangum and Schopf1, having measured oxygen consumption in Bugula turrita, concluded that diffusion alone was insufficient to supply oxygen to all parts of the zooid. They proposed a circulation of body fluid, brought about by the periodically repeated process of retraction and protrusion of the lophophore and tentacles, which is observed in these organisms. This, they supposed, would cause the transfer of oxygen-rich coelomic fluid from the region of the lophophore and tentacle sheath to the lower part of the zooid.

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    Mangum, C. P., and Schopf, T. J. M., Nature, 213, 264 (1967).

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RYLAND, J. Respiration in Polyzoa (Ectoprocta). Nature 216, 1040–1041 (1967).

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