Body not firm, transparent; head broad, neck fairly well differentiated. Two pairs of lateral fins. Anterior fins beginning well posteriorly of ventral ganglion, very small, round and partially rayed. Posterior fins angular and partially rayed. Collarette and alimentary diverticula absent. Eyes small, with small pigment spot.
Ovaries long and narrow; ova small. Seminal vesicles small, round, located near the tail fin.
Hooks: 7-10. Teeth in two rows, anterior 3-5 and posterior 0-6.
Maximum body length 70 mm, relative tail length 16-20% (S. hexaptera is one of the largest chaetognath species).
Epi- and mesopelagic, but mainly from 0 to 300 m depth.
Distribution in the North Sea
Northern North Sea.
Cosmopolitan temperate and warm oceanic waters.
[After Pierrot-Bults and Chidgey, 1988]