Pacific Rocky Intertidal Monitoring: Trends and Synthesis
Pollicipes polymerus (Sowerby 1833)
Phylum Arthropoda, class Maxillopoda, order Pedunculata, family Pollicipedidae
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A stalked barnacle that grows to 8 cm tall with more than 5 white shell plates surrounded by scales and a black, tough, fleshy peduncle roughened by inconspicuous calcareous spicules (Morris et al. 1980). The mantle (upper portion of body under plates) is typically black, but can be a brilliant red in low-light areas, such as in caves or on the undersides of rocks (J. Pearse, pers. com.).
Habitat and Geographic Range
Common species that usually grows in clusters but is also found mixed with the California Mussel, Mytilus californianus, P. polymerus inhabits the middle intertidal zone on wave-exposed, rocky shores (Morris et al. 1980) from Sitka, Alaska south to at least Punta Abreojos (Baja California) (Ricketts 1985).
Other goose barnacles such as Lepas are oceanic and attach to floating logs, net floats and other objects that sometimes wash ashore.
Pollicipes polymerus feed on particles of detritus in the backwash of waves (Morris et al. 1980) and, for this reason, are found in crevices or areas that channel water back to the ocean (Kozloff 1983). Pollicipes are brooders, and swimming nauplii larvae are released about 30 days after fertilization (Morris et al. 1980). Young goose barnacles settle preferentially among other Pollicipes, forming tight clusters on exposed outcrops, ridges and walls, just above or intermixed with mussel beds. Goose barnacles are slow-growing, reaching sexual maturity at around 5 years and living up to 20 years (Morris et al. 1980). The body temperature of P. polymerus can be colder than expected from corresponding ambient temperatures due to evaporation from the peduncle (Morris et al. 1980). They are resistant to desiccation and can withstand all but the highest wave exposures. Pollicipes have been shown to be susceptible to oiling (Foster et al. 1971, Chan 1973) and recovery from disturbance may be slow. Another Pollicipes species (Pollicipes pollicipes) is collected for human consumption in European countries. Since P. pollicipes has been in short supply, Pollicipes polymerus has been exported from British Columbia to these countries (Morris et al. 1980). Populations have been reduced in accessible areas where goose barnacles are collected for food.