Northern beroid

Geographic Origin and Biotope: Beroe cucumis is documented in cold and temperate waters of the Atlantic and Pacific. It is a gelatinous water-column animal tied to local conditions that must not be generalized.

Taxonomy and Morphology: WoRMS accepts Beroe cucumis in class Nuda, order Beroida, family Beroidae. It has a gelatinous body with eight comb rows and a broad mouth, without tentacles.

Social Behaviour: This is not a conventional aquarium community animal: it drifts or swims in the water column, and repeated contact with conspecifics, walls or décor can damage tissue. Any display group needs a density selected by experienced staff.

Colouration and Sexual Dimorphism: Transparency and the features evoked by the common name “Northern beroid” aid observation, but color and form vary with life stage, food and lighting. Sex cannot be identified reliably from the medusa's external appearance.

Aquarium Setup: A dedicated kreisel or pseudokreisel without sharp edges is required, with laminar flow that suspends Beroe cucumis without sweeping it against a surface. Intakes, drains and overflows need fine even guards; free bubbles and abrasive décor are excluded. Care remains specialist and normally institutional.

Feeding and Diet: Offer suitably sized live or enriched planktonic prey in frequent small feeds; beroids prey on other comb jellies. Remove excess promptly without suctioning tissue.

Water Quality: No species-specific numerical range is published here: temperature, pH and salinity must follow source-population evidence rather than extrapolation from related taxa. Stability, oxygenation and control of ammonia, nitrite and heavy metals take priority over an undocumented target.

Compatibility and Coexistence: Use a species-only system: fish, crustaceans, corals, anemones and other gelatinous species can prey, be stung, compete for food or cause abrasion. Prevent collisions and crowding even among conspecifics.

Aquarium Breeding: Comb jellies are generally hermaphroditic and produce planktonic larvae; closing the cycle requires separate cultures and microscopic prey.

Risks and Disease: The main risk is mechanical damage to tissue made almost entirely of water, followed by starvation, fouled screens and osmotic shock. It has no nematocysts: prey are caught with colloblasts and it is non-stinging, although identity must be confirmed before handling any gelatinous animal.