Zooplankton of the open Baltic: Extended Atlas - IOW

Trochophores and metatrochophores of polychaetes are easily confused
with each other and are difficult to assign to a specific genus, or even to a
family taxon.
Larvae of Spionidae (palp worms, the largest group of benthic, sessile
of hemi-sessile polychaetes) are generally the most common developmental
stages of polychaetes that can be found in plankton throughout the year. High
abundance of polychaetes larvae in the pelagial of the sea is not only due to
the large number of species in the coastal areas but also to the often longlasting
periods of their development.
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