(No common name)

ORDER

Aphragmophora

FAMILY

Sagittidae

TAXONOMY

Sagitta setosa Müller, 1847, North Sea.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Individuals have 8–9 hooks, 6–8 anterior teeth, and 10–16 posterior teeth. Maximum adult body length is 0.55 in (14 mm), and the relative tail length is 16–25% of total body size. The body is small, narrow, and transparent. There are two pairs of lateral fins and no fin bridge. Anterior fins are relatively short, completely rayed, and round. Posterior fins are short, completely rayed, and round. The collarette is small or not present, and there are no gut diverticula. Eyes have star-shaped pigment spots. Seminal vesicles are present in the head and trunk, touch the tail fin, and are somewhat separated from the posterior fins. Ovaries are short and ova are small. Recent molecular evidence has revealed substantial genetic differences between populations from the North and Mediterranean seas.

DISTRIBUTION

Neritic, occurring in the North, Mediterranean, and Black seas.

HABITAT

Lives in shallow pelagic waters of the Mediterranean, Black, and North seas, especially where the continental shelf is relatively wide. Reported to tolerate different degrees of salinity and may inhabit inshore waters and estuaries. Occurs in the western part of the Baltic Sea as long as the salinity is not too low.

BEHAVIOR

Nothing is known.

FEEDING ECOLOGY AND DIET

Prefers small copepods. Feeds at night after moving to superficial layers.

REPRODUCTIVE BIOLOGY

Reproduces once a year, during the summer months with a peak in late August. Hermaphroditic, and sperm is stored in the oviducts waiting for the eggs to mature. Fertilized eggs are released in the sea water. There is no larval stage.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

Used as an indicator species to follow the movement of water masses.