Description: A feather-like hydroid with central main stem and numerous side branches arising in a flat plane. The side branches are composed of separate joints each bearing a hydrotheca and defensive nematophores which have no nematothecae. The gonothecae are spherical, borne in abundance along the central region of the colony. The colonies are normally colourless to pale grey, the gonothecae may be white or pink. Fully grown colonies are typically 70-80 mm in height by 15 mm in width.

Habitat: This is a common species in a wide variety of sublittoral habitats, occurring on bedrock in exposed places and attached to shells and stones in sheltered muddy channels with slight to moderate tidal streams.

Ecology: The nudibranchs Doto dunnei and Eubranchus vittatus are often found feeding on this hydroid.

Distribution: Widely distributed in the British Isles.

Similar Species: Very similar to the other Kirchenpaueria species, Plumularia setacea, and young colonies of Polyplumaria frutescens.

Key Identification Features:

• Fine feather-like structure
• Side branches with all sections bearing hydrothecae

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

iNaturalist: Kirchenpaueria pinnata at iNaturalist World Species Observations database.

WoRMS: Kirchenpaueria pinnata at World Register of Marine Species. Accepted name: Kirchenpaueria pinnata (Linnaeus, 1758). AphiaID: 117674.

Classification: Biota; Animalia; Cnidaria; Medusozoa; Hydrozoa; Hydroidolina; Leptothecata; Plumularioidea; Kirchenpaueriidae; Kirchenpaueria