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Author: Valenciennes, 1849

Argyropelecus aculeatus Valenciennes, 1849

Diagnosis: body laterally compressed, deep; eye tubular directed dorsally; mouth vertical; enlarged caniniform teeth in lower jaw; gillrakers on first arch 15-17; branchiostegal rays 10, 3 on epihyal. Dorsal finrays 9 followed by a dorsal adipose fin; dorsal blade long derived from 7 supraneurals, the exposed parts of posterior two fused together; pectoral finrays 9-10; pelvic finrays 6; anal finrays 7 + 5. Upper preopercular spine short, extending little, if at all, beyond posterior edge of preopercle; lower preopercular spine short, curving outwards and ventrally, its length always less (usually less than 75%) than ventral length of anterior two PV photophores; postero-ventrally directed post-abdominal spine longer, markedly larger, than antero-ventral one (may be equal in metamorphic post-larvae); mid-anterior projection of antero-ventral post-abdominal spine long, extending to or near anterior margin of posterior ventral keel scale (key Fig. 2b); anterior margin of posteriormost ventral keel scale curving markedly forwards (metamorphic post-larvae excluded); spinelets present: along ventral keel (fishes over about 30 mm SL); along anterior 5 dorsal blade spines and dorsal rim of dorsal blade (over 27 mm SL). Spines present: sub-caudally, anterior to AC2 (over about 23 mm SL) and ventral to anterior 3 AC2 photophores (over about 35 mm SL); ventral to third and fourth VAV photophores (over about 35 mm SL); 3-4 (6) between anal finray groups (over about 23 mm SL) and 1 (2) between anal finrays 8-9 (over about 35 mm SL). Vertebrae 35-36. Swimbladder well developed, gas-filled, euphysoclistous. Scales deciduous. Photophores (adult): ORB 1, pigmented, directed towards eye lens; BR (6); OP 3; OP3 first to develop; IP (6); PV (12); VAV (4); ACI (6); AC2 (4); OA (2) + 6; VAV, ACI and AC2 groups well separated, the photophores of each sharing a common photogenic mass; VAV, ACI and AC2 elevated relative to posterior 6 OA. Colour: back dark, flanks silver; dark pigment triangle at base of ventral caudal lobe (fishes over 20 mm SL); marked extension of pigment to ventral keel rim below fifth to eighth PV in postmetamorphic stages. Size: to about 70 mm.

Habitat: oceanic, mesopelagic at 100-600 m, concentrated at 300-600 m by day, 100-300 m by night; juveniles and adults, diel vertical migrants. Food: selective dusk-time feeder primarily on conchoecid ostracods, to lesser extent on copepods, decapod larvae, fish larvae, etc. Reproduction: dioecious; adult photophore complement acquired at about 15 mm SL.

Distribution: bi-antitropical in Atlantic, subtropical; common in eastern North Atlantic about 25-35° N; northern record, 45° N, 30° W; absent in Mediterranean.

Eggs, larvae and young stages. Brauer, 1906: 112, fig. 48-55 | Jespersen, 1915: 11.
Otoliths (sagitta). No data.

Argyropelecus aculeatus