"Of the six species of the German coasts, Nereis diversicolor and Nereis
virens* only are able to swim by undulatory movements, while the atokous
stages of the other four species, Nereis pelagica, N. longissima, N. fucata
and N. succinea, cannot swim. In the indigenous Nereis species the atokous
stages of only those species can swim, which do not metamorphose to
heteronereids at maturity. From the literature it cannot be concluded whether
this is a general rule in Nereididae, since notes on the ablility to swim are
usually not made. If this rule should be valid, the swimming ablility of
atokous Nereididae would be unusual, as only a small minority of species of
this familiy does not metamorphose to swarming heteronereids (Clark 1961).
Translated from Goerke, H. (1971), Veröff. Inst. Meeresforsch. Bremerh. 13, p.
Therefore, usually either the atokous or the epitokous forms of the Nereididae
might distribute with currents by swimming. This rule would implicate that a
family of fundamental morphology would widely lack a fundamental mode of
locomotion as long as transformation to the heteronereis is not finished. E.g.
Nereis pelagica, if suspended in the free water, performs nematode like
movements (see Film C 1602 of IWF Goettingen: Bewegungsweisen bei Nereis-
*) Only subepitokous stages are formed. On the German coasts, the males
swarm, but the females do not.
für Polar- und Meeresforschung
e-mail hgoerke at awi-bremerhaven.de
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