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Swimming juvenile nereids?

Helmut Goerke hgoerke at awi-bremerhaven.de
Thu Mar 3 14:24:11 EST 2005

"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.

Helmut Goerke
für Polar- und Meeresforschung
D-27515 Bremerhaven

e-mail  hgoerke at awi-bremerhaven.de

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