Metschnikow, 1865
Description
Body elongated, finger-shaped, without cilia. Proboscis beset with rod-shaped epithelic protuberances. Because the proboscis is not retractable, it remains visible in preserved specimens. Two black and kidney-shaped eye spots behind proboscis, embedded in the epithelium A.composita-d.
Mouth on ventral side, just behind the basis of the proboscis.
A. composita is able to reproduce asexually, zooids are budded off by transverse fission and form chains of four (rarely 10) zooids A.composita-d.
Colour
Bright yellow, proboscis green-yellow.
Size
Length of solitary animal about 0.9-1 mm; length of zooid chain up to 2.5 mm.
Depth range
Epipelagic; unknown whether the species is coast-bound or not..
Ecology
A. composita is a truly planktonic turbellarian; greatest abundances during June-August (Greve and Reiners, 1996); this turbellarian must be considered as an important predator on copepods (but is also consuming diatoms and tintinnoids).
Distribution in the North Sea
Wad, German Bight, Skagerrak, Kattegat.
World distribution
North Atlantic Ocean, from NE America to Europe, White Sea.
[See Hansson, 1998d for distribution]