Haliclystus octoradiatus is a stalked jellyfish (class Staurozoa, family Haliclystidae) found in cold temperate coastal waters of the northern Atlantic and Arctic, attaching to macroalgae and seagrasses with a funnel-shaped body bearing eight clusters of capitate tentacles for feeding on small crustaceans and invertebrates. As a staurozoan lacking the free-swimming medusa stage, it is important for understanding the evolution of cnidarian life cycles. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.