Biodiversity & Conservation

Poli's stellate barnacle - Chthamalus stellatus

Chthamalus stellatus

Image Alan J. Southward - Close up of Chthamalus stellatus from about Mid Tide Level seen underwater. Image width ca 12 mm.
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Distribution map

Chthamalus stellatus recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

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Chthamalus stellatus is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Arthropoda Arthropods, joint-legged animals, e.g. insects, crustaceans & spiders
Class Maxillopoda Barnacles, copepods and fish lice
Authority Poli, 1791
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland A southern, warm-water species recorded on the south and west coasts of the British Isles as far north as the Shetland Isles. The species is less abundant along the channel towards The Isle of Wight, its eastern limit.
Habitat information icon Habitat information Recorded in the mid to low eulittoral zone on exposed rocky shores. Its vertical distribution overlaps with Chthamalus montagui and Semibalanus balanoides.
Text page icon Description An intertidal barnacle with six solid wall plates, an oval-shaped operculum opening, and a membranous base. Juveniles have a kite-shaped opercular opening. The rostral plate is relatively narrow, plates are of roughly equal size, and its rostral plate is not fused with the rostrolateral plates. Usually conical in shape, however when crowded may become tubular. It may reach a diameter of approximately 14 mm, depending on habitat, food availability and level on the shore. The tissue inside the opercular aperture is bright blue with black and orange markings.
Identifying features
  • Shell wall of six solid plates.
  • Oval-shaped operculum opening.
  • Joint between the terga and scuta crosses the centre line at one third or more of the distance towards the rostrum.
  • Tissue inside the operculum opening is usually bright blue with brown and orange markings.
  • Junction between the terga and scuta is convex towards rostral plate.
  • Shell base is membranous.
Additional information icon Additional information Before 1976 Chthamalus montagui was considered a variety of Chthamalus stellatus, but in 1976 was identified as a distinct species, due to differences in its vertical zonation on the shore and morphology, particularly in the shape of the opercular plates, setation of the smaller cirri. (Southward, 1976).

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This review can be cited as follows:

Karen Riley 2002. Chthamalus stellatus. Poli's stellate barnacle. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=2982>