California Acorn Barnacle, Megabalanus californicus

California Acorn Barnacle, Megabalanus californicus. Cluster Size: 10 cm (4.0 inches) x 10 cm (4.0 inches) x 13 cm (5.1 inches).

Phylogeny:  The California Acorn Barnacle, Megabalanus californicus (Pilsbry, 1916), is a member of the Balanidae Family of Acorn Barnacles. It is also known as the Red-striped Acorn Barnacle and the White-ribbed Red Barnacle. In Mexico, it is known as Percebe Californiano.

Morphology:  The California Acorn Barnacle has steep sides with red and white striped plates that are separated white relatively white plates. The mantle of living specimens is blue, orange, red and blue. The top opening is wide that helps distinguish this barnacle from the similar Titan Acorn Barnacle. The California Acorn Barnacles reach a maximum of 3.0 cm (1.2 inches) in diameter.

Habitat and Distribution:  California Acorn Barnacles are found attached to hard surfaces including buoys, crustacean shells, mollusk shells, pilings and rocks as individuals or in clusters. They are found in the intertidal zone to depths up to 12 m (40 feet). In Mexican waters they are a resident of the Pacific and found along the entire west coast of Baja and within the Sea of Cortez from Santa Rosalia south to Cabo San Lucas, Baja California  Sur. Following an  El Niño weather event, the California Acorn Barnacle can be found in more northern areas.

Reproduction: The California Acorn Barnacle is hermaphroditic and reproduces via broadcast spawning. The eggs are fertilized in the mantle cavity, forming planktonic nauplii larvae. After several larval stages the organisms cements onto a substrate and undergoes metamorphosis.

Common Misidenification:  This species can be confused with the Titan Acorn Barnacle, Megabalanus coccopoma (paler in color and has a smaller opening).

Synonym:  Balanus tintinnabulum californicus.