Stings are painful; second most important stinging jellyfish on the southcoast of Italy; in the coast of Denia (Western Mediterranean Sea), summer of 2008, it showed an unusual high density and stung as many as 185 people d-1 (Ref. 116819). Neritic (Ref. 116114). Inhabits near shore, mangrove channels, and kelp forests (Ref. 1028). Polyps were once located attached to bivalve shells in a mangrove habitat in Puerto Rico, suggesting estuarine polyps (Ref. 116835). Medusae are associated with sandy beach with Posidonia oceanica meadows (Ref. 116819). Pathogenic (Ref. 116114). Mainly feeds on copepods, mysids and gammarids (Ref. 116521). Temperature is the main factor which affects its spatio-temporal abundance along the SW Mediterranean; other variables were low salinity and high coastal productivity (chl a and phosphate) (Ref. 116819).