Gooseneck (or Leaf) Barnacles (Pollicipes polymerus)
Contributed by Dr. Bonnie Becker
Where found: Usually restricted to the upper two-thirds of the intertidal. Found on the sides of rocks in aggregations mixed with California mussels.
- Although they look more like they are molluscs (related to animals with shells, like mussels and clams), they are actually crustaceans. That means they are more closely related to lobsters and crabs than to seashells.
- These animals are very often found in conjunction with California mussels and seastars. BPT refers to this as the Mytilus-Pollicipes-Pisaster association. Pisaster is noticeably missing from the Cabrillo National Monument tidepools.
- Gooseneck barnacles are able to bend and twist on their stalks. This reaction can be elicited by creating a shadow over a cluster of animals, which will cause them to shift directions in a synchronized manner.
- The “necks” of gooseneck barnacles have been considered a delicacy by Spaniards and Italians.
- Goose barnacles got their name in the sixteenth century, when they were described by John Gerard as a “Barnakle tree, or a tree bearing Geese”.
Adaptations: See the acorn barnacle section.
Food: Gooseneck barnacles eat larger food than acorn barnacles, eating amphipods and other creatures up to the size of houseflies. They capture their food from the currents with their cupped appendages. Since they rely on currents to capture their food, it is common for the groups of animals to align with the direction of current movement
Life history: Gooseneck barnacles are closely related to acorn barnacles, and have basically the same life history traits. They reach maturity in the first year and breed from late April to October. They are hermaphroditic, although they are thought not to be able to fertilize their own eggs. They brood their embryos. Throughout the year, they produce three to seven broods, with 100,000 to 240,000 larvae per brood.
Phylum: Arthropoda (Firm, jointed exoskeleton and jointed appendages)
Class: Crustacea (Barnacles, Beach hoppers, Shrimps, Lobsters, Crabs, etc.)
SubClass: Cirripedia (Barnacles)
Last revised 24-Nov-17