Description: It is a small to medium-sized jellyfish belonging to the hydrozoans, characterized by a delicate, transparent, hemispherical bell, usually not exceeding 4 cm in diameter. The body is almost colorless, sometimes displaying faint whitish or bluish hues, giving it an ethereal appearance in the water. Along the margin of the bell, four long main tentacles alternate with shorter ones, all equipped with stinging cells. The short central manubrium and internal structures are clearly visible due to the high transparency of the body.

Geographic distribution: This species shows a widely cosmopolitan distribution, occurring in temperate and tropical oceans worldwide. In the southwestern Atlantic, it is commonly recorded from southern Brazil to the Argentine coast, including the Río de la Plata and nearby coastal waters. Its occurrence is often seasonal, with higher abundance during warmer months.

Habitat: It primarily inhabits coastal and neritic marine environments, but it can also be found in offshore waters. It is a strictly pelagic species, associated with the upper layers of the water column, where it moves through both active swimming and passive drifting with currents. It favors waters with high plankton availability and moderate to warm temperatures.

Feeding: The diet consists mainly of microzooplankton, including small crustaceans, invertebrate larvae, and other planktonic organisms. Prey capture is achieved through tentacles armed with cnidocytes, which paralyze organisms upon contact. The manubrium then transports the prey to the mouth. It plays a significant role as a predator within planktonic food webs.

Behavior: The species exhibits a mostly passive behavior, with gentle movements generated by rhythmic bell pulsations. Individuals are often observed singly or forming small aggregations, particularly under favorable environmental conditions. It is a fragile species, sensitive to sudden environmental changes.

Reproduction: It has a typical hydrozoan life cycle, alternating between a sexual medusa stage and an asexual polyp stage. Sexual reproduction occurs in the medusa, with gametes released into the water column. After fertilization, a planula larva develops and gives rise to a microscopic polyp, which later produces new medusae by budding.

Conservation status: The species has not been specifically assessed at a global level. It is not considered threatened, and its populations show natural fluctuations closely related to oceanographic and climatic factors, with no current evidence of sustained decline.

Author of this compilation: EcoRegistros – 01/18/2026