Chiasmodon niger (Johnson 1864, up to 25cm) is the extant black swallower, a deep sea lizardfish capable of swallowing, but not necessarily digesting before decomposition, prey larger than itself. Scales are absent.

Cyclothone elongata (Günther, 1878) Synonym for Sigmops elongatus (Günther, 1878). Original name. Gonostoma elongatum Günther, 1878. Goode and Bean 1883 - this species may no longer be recognized) is an extant bristlemouth, one of the most abundant fish ion the planet.

Gonostoma elongatum (genus: Rafinesque 1810; species: Girard 1858; 30cm) is the extant bristlemouth, deepsea fish that make up for their lack of diversity with relative abundance, numbering in the hundreds of trillions to quadrillions. They mainly feed on zooplankton and small crustaceans due to their small size (2 to 30 cm, average 7.5cm). They begin their lives as males and some of them switch to female.

Chauliodus sloani (Forster in Bloch and Schneider 1801, up to 60cm in length) is the extant viperfish. A tiny glowing lure from the anterior dorsal fin lure deep sea fish to the oversized teeth. Scales and maxillary teeth are retained. Apparently the temporal series were not retained. The anterior dorsal fin is new. Sister to Leptolepis (above).