Cladonema radiatum is a hydrozoan (family Cladonematidae) found in coastal waters of the northeastern Atlantic and Mediterranean, alternating between a branching hydroid colony stage and a free-swimming but crawling medusa stage with adhesive branched tentacle tips. The species has been used as a model system for studying hydrozoan regeneration, cnidarian biology, and the evolutionary origins of medusa complexity. Its accessible biology and small size make it a promising model for laboratory studies of hydrozoan development and regeneration. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.