English: Marine smelts and allies.
Genera: 60; 228 species; 6 to 7 families.
Habitat: bathypelagic ocean.
ZoologyFish: they have a physoclistous gas bladder or lack it entirely; teeth are absent in almost all; hypaxial muscle is unusually extended to forward at its upper end, attaches to the neurocranium below the spine, perhaps to snap the upper part of the skull down when catching prey; primordial ligament attaches posteriorly on the upper surface of the coronoid process; the autopalatine is peculiarly expanded to above and below at its caudal end; the caudal part of the mesethmoid appears compressed when seen from above; autopterotic and dermopterotic bones are not fused together; crumenal organ, also called epibranchial organ, consists of the additional cartilage and gill rakers on the fifth ceratobranchial, well-developed.
Size: smallish.
Color: silvery or dark.
Fins: adipose fin, unusually for
Protacanthopterygii; dorsal fin is located in the second half of the body.
TaxonomyArgentiniformes formerly were included in the
Osmeriformes. Studies show they may actually be the most basal lineage of the living
Protacanthopterygii. It would probably require either inclusion of the supposed superorders Cyclosquamata and Stenopterygii in the
Protacanthopterygii. Or Euteleostei is used for this entire group, restricting the
Protacanthopterygii to the
Osmeriformes and either
Esociformes or
Salmoniformes.
FamiliesAlepocephaliformes.
• Alepocephalidae: Slickheads), includes Bathylaconidae; Leptochilichthyidae.
• Platytroctidae: including Searsiidae.
Suborder Argentinoidei
• Argentinidae: Herring smelts.
• Bathylagidae: Deep-sea smelts.
• Microstomatidae: Pencil smelts.
• Opisthoproctidae: Barreleyes.