Ref ID : 2139
Ann Alberts Allen; Morphology of the planktonic rotifer Polyarthra vulgaris. Trans.Amer.Micros.Soc. 87(1):60-69, 1968
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Certain features were found which contribute to the widespread success of Polyarthra vulgaris as a planktonic organism. The integument is modified internally into posterior attachment ledges and anterior hook-like structures to which the well-developed longitudinal muscles controlling the paddles are attached. An extracellular cuticle is present on parts of the body wall, but most of its rigidity appears to be provided by an intracellular layer of varying thickness, called the rigid intracellular layer by Koehler (1965). There is continuity between the pseudocoel and the cavity of the paddles, suggesting that they may arise as hollow bladders which become flattened. The lateral antennae, egg thread gland, and musculature are described. An organelle, possibly chemo-tactic in function, and found at the mouth opening is also described. Almost all of the adaptations observed contribute to the skipping motion for which Polyarthra is noted. The usefulness of this motion is escaping from predators is discussed.