Mitella polymerus (Sowerby, 1833)

Goose Neck Barnacle, Leaf Barnacle
Synonyms: Mitella polymerus
Phylum Arthropoda
 Subphylum Crustacea
  Class Maxillopoda
   Infraclass Cirripedia
    Superorder Thoracica
     Order Pedunculata
      Suborder Scapellomorpha
       Family Scalpellidae
Rosette of Leaf Barnacles (Pollicipes polymerus) at Swirl Rocks, WA.  Approximate length of capitulum is 3 cm.
(Photo by: Melissa McFadden, June 2002)
Description:  The body of this organism is up to 8 cm long.  The capitulum is protected by five large, whitish plates and several smaller ones which lie in basal whorls.  The carina lacks spines, and the tough, fleshy peduncle allows for elasticity to the force of the surface.  The color is dark brown and contains many calcareous spicules embedded in its surface.

How to Distinguish from Similar Species:  There is a pelagic goose barnacle, Lepas anatifera, frequently found in the Pacific Northwest that looks somewhat similar to M. polymerus, however is has fewer plates and only occurs in the open sea and on driftwood washed ashore.  There is a closely related European species, Pollicipes pollicipes, which is cooked and served as a delicacy.  However, it is now in short supply and M. polymerus has been exported from British Columbia to Portugal and Spain.

Geographical Range:  This species of barnacle is found as far north as Southeast Alaska to Baja California in the south.

Depth Range:  P. polymerus occurs in the high to middle intertidal zones.

Habitat:  This barnacle prefers open, surf-swept coastlines.  It has also been reported to occur on other barnacles on the skin of Humpback Whales.

Biology/Natural History:  This species feeds by growing outward so that it can extend its cirri in a fan oriented perpendicular to the backwash of the waves.  Small particles of detritus and tiny crustaceans get caught in the cirri, which are subsequently eaten.  Predators of M. polymerus include the ochre sea star (Pisaster ochraceus) and the Glaucous-winged Gull (Larus glaucescens). M. polymerus directly competes with the California Mussel (Mytilus californianus) and can often out-compete them, but they are more vulnerable to predation by gulls. M. polymerus often grows in tight bunches (rosettes) which make them more resistant to predation.  In the Puget Sound, Goose Neck barnacles breed from April to October, peaking in July.  Individuals are hermaphroditic, but will always cross-fertilize.  Each sexually mature individual may produce up to four broods per year, with up to 20,000 developed young per brood.  The young aggregate at the base of the adults, where their survival rate increases.  Within one month they are able to attain independence.  Current research includes energy flow within ecosystems containing M. polymerus and the accumulation of toxins within the mussel tissue.
Note:  The genus Pollicipes has an unusual distribution of W. Europe, NW Africa, and W North and Central America (Newman and Killingsley, 1985; Newman 1987, 1992).  Newman attributes this distribution to a relict of the Tethys Sea.


References:
Dichotomous Keys:
  Kozloff, 1987, 1996.
  Smith and Carlton, 1975

General References:
  Brandon and Rokop, 1985
  Carefoot, 1977
  Gotshall, 1994
  Harbo, 1999
  Hinton, 1987
  Johnson and Snook, 1955
  Kozloff, 1993
  McConnaughey and McConnaughey, 1985
  Morris et. al. 1980.
  Niesen, 1994
  Niesen, 1997
  O’Clair and O’Clair, 1998.
  Ricketts et al., 1985

Scientific Articles:
Newman, W.A., 1987.  Southern hemisphere endemism among the barnacles:  Explained in part by extinction of northern members of amphitropical taxa?  Bulletin of Marine Science 4(2): 603-619

Newman, W.A., 1992.  Biotic cognates of eastern boundary conditions in the Pacific and Atlantic: Relicts of Tethys and climatic change.  Proceedings of the San Diego Society of Natural History 16: 1-7

Newman, W.A. and J.S. Killingsley, 1985.  The north-east Pacific intertidal barnacle Pollicipes polymerus in India?  a biogeographical enigma elucidated by 18O fractionation in barnacle calcite.  Journal of Natural History 19(6): 1191-1196

Wootton, J.T., 1993.  Size-dependent competition--effects on the dynamics vs the end-point of mussel bed succession.  Ecology 74:1 pp. 195-206


 
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General Notes and Observations:  Locations, abundances, unusual behaviors, etc.:


Pollicipes polymerus at Slip Point, Clallam Bay, WA.  Photo by Dave Cowles, 7-1997


A cluster of Pollicipes polymerus under a boulder at Cape Flattery.  Photo by Dave Cowles, July 2004


Gooseneck barnacles often compete with California mussels for space (and if undisturbed, the mussels usually win).  Photo by Dave Cowles, Shi Shi Beach, Sept 2005


Authors and Editors of Page:
Melissa McFadden (2002):  Created original page
Edited by Hans Helmstetler: 10-2002
Edited by Dave Cowles, 2005, 2007