Description: The main stems arise from a creeping stolon, and are slender, straight, and branch irregularly. There are several annulations after each branching. The branches are short and and arise at the internodes, they give rise to ringed pedicels which each support a single hydrotheca. The hydrothecae are bell shaped and delicate, with a smooth outer rim. The gonothecae are also situated on ringed pedicels, they are roughly tubular in shape, tapering towards the base. The aperture is slightly raised and the outer margin is smooth.

Habitat: This species often grows attached to other hydroids.

Distribution: A common species around the British Isles.

Distribution Map from NBN: Obelia dichotoma at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Obelia dichotoma at iNaturalist World Species Observations database.

WoRMS: Obelia dichotoma at World Register of Marine Species. Accepted name: Obelia dichotoma (Linnaeus, 1758). AphiaID: 117386.

Classification: Biota; Animalia; Cnidaria; Medusozoa; Hydrozoa; Hydroidolina; Leptothecata; Campanulariidae; Obelia