Hydrocenidae are widespread across the Palearctis and Africa, but reach their highest diversity in the Oriental, Australian, and Oceanian regions.

The family is poorly known and has not been revised in the past 140 years and as a consequence, the status of the various genus names (including Georissa) is uncertain.

[1] The eyes are prominent, situated at the upper or outer base of the tentacles.

[1] The numerous lateral teeth are denticulate, and arranged in very oblique series.

[1] Genera and species within the family Hydrocenidae include:[2] This article incorporates public domain text from the reference.