Other Free Encyclopedias » Animal Life Resource » Mollusks, Crustaceans, and Related Species » Barnacles and Relatives: Thecostraca - Physical Characteristics, Habitat, Behavior And Reproduction, Barnacles, Their Relatives, And People, No Common Name (trypetesa Lampas): Species Accounts - GEOGRAPHIC RANGE, DIET, CONSERVATION STATUS

Barnacles and Relatives: Thecostraca - Rock Barnacle (semibalanus Balanoides): Species Accounts

water attach accessed food

Physical characteristics: Rock barnacles measure 0.19 to 0.59 inches (5 to15 millimeters) across. The shell is made up of six gray or white plates that are fused together. Two of the plates form a cover that opens and closes. Through this opening six pairs of biramous (BY-ray-mus), or branched, cirri fan out into the water or can be safely withdrawn inside. Tissue inside this opening is white or pinkish.

Geographic range: Rock barnacles are found in intertidal rocky shores in North America, Europe, and the Arctic.

Habitat: Rock barnacles attach themselves to rocks, pilings, and crabs. They prefer low tide areas sometimes splashed by water.

Diet: They eat bits of food floating in the water.

Behavior and reproduction: Rock barnacles feed only during high tide when the shell is covered by water. Food is collected from the Rock barnacles attach themselves to rocks, pilings, and crabs. (Dr. Eckart Pott/OKAPIA/Photo Researchers, Inc.) water by the last three pairs of cirri that form a fan-shaped net. The cirri are extended and withdrawn inside the shell 33 to 37 times a minute as they collect food from the water.

Individuals are hermaphrodites. Eggs are fertilized in the mantle cavity and six thousand to thirteen thousand nauplius larvae develop there. The non-feeding larvae attach themselves to objects using their antennules. Rock barnacles live a total of three to eight years.

Rock barnacles and people: Rock barnacles are studied by scientists interested in learning how animals live and survive in harsh seashore habitats.

Conservation status: This species is not considered threatened or endangered. ∎



Anderson, D. T. Barnacles. Structure, Function, Development and Evolution. Melbourne, Australia: Chapman and Hall, 1994.

Brusca, R. C., and G. J. Brusca. Invertebrates. Second edition. Sunderland, MA: Sinauer Associates Inc., 2003.

Stott, R. Darwin and the Barnacle: The Story of One Tiny Creature and History's Most Spectacular Scientific Breakthrough. New York: W. W. Norton & Company, 2003.


"Earth Almanac. Hot Stuff. Pepper Paint Foils Barnacles." National Geographic (May 1994) 185, no. 4.

Starbird, E. A. "Friendless Squatters of the Sea." National Geographic (November 1973) 144, no. 5: 623-633.

Web sites:

Barnacles. http://www.old.umassd.edu/public/people/kamaral/thesis/Barnacles.html (accessed on March 21, 2005).

Biology of the Barnacles. http://www.mov.vic.gov.au/crust/barnbiol.html (accessed on March 21, 2005).

Introduction to the Cirripedia—Barnacles and Their Relatives. http://www.ucmp.berkeley.edu/arthropoda/crustacea/maxillopoda/cirripedia.html (accessed on March 21, 2005).

[back] Barnacles and Relatives: Thecostraca - No Common Name (trypetesa Lampas): Species Accounts

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or