Beroe gracilis is a translucent, elongated, hollow, cylindrical animal with a maximum length of about 4 cm (1.6 in).

[4] This comb jelly forms part of the nekton, animals that actively swim rather than passively drift like plankton, and usually occurs in the top 100 m (330 ft) of the water column.

[3] Beroe gracilis is a voracious predator, feeding almost exclusively on other comb jellies, such as Pleurobrachia pileus.

[3] It swims rapidly with its mouth open wide, drawing prey into its pharynx, and processing it with the help of specialised cilia; digestion is extracellular and takes place in the body cavity.

[3] The warty comb jelly Mnemiopsis leidyi has become invasive in European waters, and sometimes forms blooms in the North Sea and Baltic Sea; Beroe gracilis has been found to readily prey on M. leidyi, but was limited in controlling the alien species by being unable to ingest prey approaching its own size.