Description: This hydroid has erect main stems with side branches at regular alternate intervals. The hydrothecae diverge little from the stem and branches. Typical size of colonies is 120mm in height.

Habitat: This is a rather scarce species, found on bedrock in exposed or moderately exposed sites, usually in the circalittoral zone.

Distribution: Widespread on the western coasts of the British Isles.

Similar Species: The overall appearance of this hydroid is most similar to some Diphasia species, but the hydrothecae in this species are subalternate as opposed to opposite in Diphasia.

Key Identification Features:

• Main stem and unbranched, alternate side branches
• Characteristic subalternate hydrothecae which are pressed close to the branches

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

iNaturalist: Thuiaria articulata at iNaturalist World Species Observations database.

WoRMS: Thuiaria articulata at World Register of Marine Species. Accepted name: Thuiaria articulata (Pallas, 1766). AphiaID: 117932.

Classification: Biota; Animalia; Cnidaria; Medusozoa; Hydrozoa; Hydroidolina; Leptothecata; Sertularioidea; Sertulariidae; Thuiaria