Kingdom Animalia
Phylum Arthropoda
Class Maxillopoda
Order Thoracica
Family Chthamalidae
Genus Chthamalus
Species stellatus
Classification Poli, 1791
Common name poli's stellate barnacle

Geographic Range Mediterranean, Black Sea, Eastern Atlantic.
Physical Characteristics it is sessile, it has an oval operculum and a scarious base which sticks to the substratum. The shell is made up of six limestone plates of similar dimension; the upper opening (operculum) can close in order to protect the animal in case of long periods out of the water and of increase in the salinity. The shell diameter may be up to 14 millimeters wide, but its dimension depends on the habitat, on the quantity of available food and on the tide level. The tissue inside the operculum is light blue with brown and orange spots.
Notes it feeds thanks to the movement of the cirri, which go out of the operculum to catch the plankton and the organic material suspended in the water. They change their moult several times to grow up. The feeding rate and the temperature determine the frequency of the moult. No moult takes place during wintertime when the levels of phytoplankton and the temperature are low. All these species grow faster during their youth and less fast afterwards; their generally conical shell tends to become tubular when the species grows in areas with a high density of individuals. The rate of growth changes according to different biological and environmental factors, such as the flow of the current, the orientation with regard to the current, the food availability, the exposure to the waves, the level of the tide, the intra- and inter specific competition. The reproduction is autogamous and that means that the female gamete is inseminated by the male gamete produced by the same individual. It reproduces every year. It is sensitive to the decrease in the salinity and to the increase in the sediment load.
Habitat it is found in the middle and low eulittoral zone on the exposed rocky coasts.

References Riserva Naturale Marina di Miramare
MarLIN: The Marine Life Information Network for Britain & Ireland
Web References http://www.units.it/~wwfmiram/
Source of the photo http://www.horta.uac.pt/

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