Body narrow, firm and opaque. Head relatively small. Two pairs of separated lateral fins. Fins rounded and completely rayed. Anterior fins beginning behind the ventral ganglion. Collarette small and very narrow. Alimentary diverticula present. Eyes with a small, round pigment spot.
Ovaries long and narrow. Seminal vesicles are conical in shape, separated from the posterior fin, and very close to, or touching the tail fin.
Hooks: 8-11, depending on the subspecies (see below). Teeth in two rows, anterior 2-10 and posterior 11-28, depending on the subspecies (see below).
Maximum body length 20-44 mm, depending on the originating waters (see below for the subspecies).
Three subspecies or forms of Sagitta elegans have been considered according to their size, which depends on the temperature of the waters in which they develop (Fraser, 1952). The number of hooks and teeth vary slightly in these forms.
¥ Sagitta elegans elegans Verill, 1873
Maximum body length 30 mm, relative tail length 17-25%. Hooks 9-11, anterior teeth 2-8, posterior teeth 12-18.
¥ Sagitta elegans arctica Aurivillus, 1896
Maximum body length 44 mm, relative tail length 15-25%. Hooks 10-13, anterior teeth 2-10, posterior teeth 16-25.
¥ Sagitta elegans baltica Ritter-Zahony, 1911
Maximum body length 20 mm, relative tail length 10-16%. Hooks 8-10, anterior teeth 4-6, posterior teeth 11-15.
Distribution in the North Sea
S. elegans elegans is the mainly coastal form, occurring in the North Sea. The other two forms occur outside the area, but S. elegans baltica has been recorded occasionally in Scottish waters.
Epipelagic in arctic and subarctic waters. According to Fraser (1952), S. elegans elegans is the coastal form with oceanic influence, S. elegans arctica is the boreal-arctic form, and S. elegans baltica is the form that occurs in and near the Baltic Sea.
[After Pierrot-Bults and Chidgey, 1988]