Balanus amphitrite Key Image

A Balanus amphitrite from San Francisco Bay, showing the bands of purple stripes that distinguish this barnacle from other species in the bay. The moveable lid, within the diamond-shaped opening, separates along a line that runs from lower left to upper right in the image. The head end of the animal is toward the lower left.

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Balanus amphitrite Key Image

Balanus amphitrite Darwin, 1854

STRIPED BARNACLE

Balanus amphitrite is a small, roughly conical barnacle that reaches a maximum diameter of about 20 mm. It has white walls with vertical bands of purple or red-brown stripes. Both the stripes and the white spaces between them are typically wider at the bottom and narrow toward the top. The walls are often smooth, but sometimes have shallow vertical ridges. Any red- or purple-striped barnacle found in San Francisco Bay is likely to be this species.

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Balanus amphitrite

Striped Barnacle

Andrew N. Cohen

A Balanus amphitrite from San Francisco Bay, showing the bands of purple stripes that distinguish this barnacle from other species in the bay. The moveable lid, within the diamond-shaped opening, separates along a line that runs from lower left to upper right in the image. The head end of the animal is toward the lower left.

Andrew N. Cohen

A side view of another Balanus amphitrite from San Francisco Bay, with a juvenile growing on it on the right.

Andrew N. Cohen

A native barnacle (Balanus glandula) flanked by two Balanus amphitrite. Balanus amphitrite’s shell is striped and smooth or sometimes shallowly ridged, while glandula’s is stripeless and often strongly ridged (as here).

Andrew N. Cohen

Another Balanus glandula with strongly ridged walls, flanked by an adult amphitrite on the left and a juvenile amphitrite on the right, on a high intertidal rock in San Francisco Bay.

Andrew N. Cohen

Balanus improvisus, an exotic, unstriped, smooth-walled barnacle that has become established in San Francisco Bay.

Ruditapes philippinarum Image 15-P laciniata detail

Detail of the interior of the preceding Protothaca laciniata shell, showing the teeth on the margin of the shell.

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Ruditapes philippinarum Image 15-P laciniata detail

Ruditapes philippinarum Image 14-P laciniata

Protothaca laciniata from San Francisco Bay. Note strong concentric ridges compared to Protothaca staminea.

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Ruditapes philippinarum Image 14-P laciniata

Ruditapes philippinarum Image 13-P staminea detail

Detail of the interior of the preceding Protothaca staminea shell, showing the teeth on the margin of the shell, which are not present in Venerupis philippinarum.

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Ruditapes philippinarum Image 13-P staminea detail

Ruditapes philippinarum Image 12-P staminea

Protothaca staminea from San Francisco Bay. Compare with the more elongate oval shape of Venerupis philippinarum.

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Ruditapes philippinarum Image 12-P staminea

Ruditapes philippinarum Image 11-for sale

Live, cultured Venerupis philippinarum for sale in a Chinese market in Oakland, California.

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Ruditapes philippinarum Image 11-for sale

Ruditapes philippinarum Image 9-some color variation

Some of the variation in color in the previous sample.

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Ruditapes philippinarum Image 9-some color variation

Ruditapes philippinarum Image 8-from sand beach

Venerupis philippinarum from a sand beach on the east shore of San Francisco Bay.

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Ruditapes philippinarum Image 8-from sand beach

Ruditapes philippinarum Image 7-in sieve from mud & cobbles

Venerupis philippinarum dug from the black mud and cobbles beneath intertidal rocks in San Francisco Bay.

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Ruditapes philippinarum Image 7-in sieve from mud & cobbles