No common name

Sagitta bipunctata

ORDER

Aphragmophora

FAMILY Sagittidae

TAXONOMY

Sagitta bipunctata Quoy and Gaimard, 1827, Strait of Gibraltar.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Individuals have 8-10 hooks, 5-8 anterior teeth, and 8-16 posterior teeth. Maximum adult body length is 0.75 in (19 mm), with a relative tail length of 22-29% of total body size. The body is firm and opaque. There are two pairs of lateral fins and no fin bridge. Anterior fins are medium in length, rounded, and completely rayed. Posterior fins are medium in length, completely rayed, and triangular in shape. This species does not have a collarette, nor does it have gut diverticula. Eyes are small, with T-shaped pigment spots. Seminal vesicles are present in the head and trunk and touch the tail fin, although they are well separated from posterior fins. Ovaries are medium in length and reach the region of the ventral ganglion; ova are large.

DISTRIBUTION

Epipelagic, occurring between 40°N and 40°S in all three oceans. HABITAT

A pelagic, oceanic species that lives in tropical and subtropical regions at depths of 0-328 ft (0-100 m).

BEHAVIOR

One of the few species in the northwest Atlantic that lives in the upper 164 ft (50 m) of the water column. Shows evidence of diurnal vertical distribution, with population numbers being most abundant at depths of 0-33 ft (0-10 m) at night and 33-82 ft (10-25m) in the daytime. Rapid darting movements are made over short distances to catch prey.

FEEDING ECOLOGY AND DIET

Prefers small copepods.

REPRODUCTIVE BIOLOGY

Reproduces one or more times a year depending on water temperature. 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

The first chaetognath species ever described. ♦

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