In many genera, the eyes are fixed gazing permanently upwards, enabling them to discern the silhouettes of prey moving overhead against the slightly brighter upper waters.

Their prey consists primarily of tiny crustaceans, such as amphipods, copepods, euphausiids (krill) and ostracods (seed shrimp), and of fish smaller than themselves.

They spawn in the open water, and do not guard or otherwise care for their offspring; species with a short lifespan are presumably semelparous The fry – even of Sternoptychinae – look like tiny pearlsides (Maurolicus).

Counterillumination (or counter-lighting) involves the production of light by the fish for the purpose of camouflaging its silhouette from observers lurking below.

Sternoptychidae produce this light with organs called photophores, of which they have between 3 and 7 – usually 6 – on the branchiostegal membrane along the lower edge of the chest and belly.

In some classifications, the "Stenopterygii" are kept separate but included with the Protacanthopterygii and the monotypic superorder Cyclosquamata in an unranked clade called Euteleostei.

The relationships of these – and the Lampriformes or Myctophiformes, which are also usually treated as monotypic superorders – to the taxa mentioned before is still not well resolved at all, and regardless whether one calls them Protacanthopterygii sensu lato or Euteleostei, the phylogeny of this group of moderately advanced Teleostei is in need of further study.

Compared to their relatives, the marine hatchetfishes are a more apomorphic group, but they have evolved in an entirely different direction from the other "advanced" lineage of Stomiiformes, the huge family Stomiidae.

While it remains to be seen what Sternoptychidae other than the pearlsides (Maurolicus, the type genus) do actually belong in the Maurolicinae, it is unlikely that the two-subfamily arrangement is correct.