The titan acorn barnacle Megabalanmus coccopoma, is not native to the
Atlantic but now occurs along the U.S. Atlantic coast and in the Gulf of
Mexico. It is a very large balanid (acorn barnacle family), pink in color and
growing to over 5 cm in height and width (Kerckhof 2002, Jaxshells).
Potentially Misidentified Species
A number of non-native balanid barnacles occur in Florida and have introduced
ranges that potentially overlap that of Megabalanmus coccopoma. The
Mediterranean barnacle Megabalanus antillensis (= Balanus
tintinnabulum) and the Pacific barnacle Balanus trigonus are two such species that are similar
in color to M. coccopoma. Balanus trigonus is distinguishable by
size, only growing to around 8 mm, while differentiating between
Megabalanus species may require taxonomic expertise beyond that of most
amateur naturalists. In the IRL region, however, M. coccopoma appears
thus far to occur primarily to the extreme northern part of the system while
M. antillensis has been found primarily at the southern end of the IRL
region, i.e., in the Loxahatchee River Estuary (McPherson et al. 1984). M.
coccopoma was reported from Port St. Lucie in 2006, however (Florida
Wildlife 2007). If this report is valid, then the IRL distribution of the two
non-native Megabalanus species may overlap.
HABITAT AND DISTRIBUTION
Megabalanus coccopoma is native to the Pacific coast of the Americas
from southern California to Ecuador. The animal now occurs in the Gulf of
Mexico and along the southeastern U.S coast from northern Florida to southern
Megabalanus coccopoma was first collected from the Cape Canaveral area
in 2006. Several specimens have also been collected around Ponce De Leon Inlet
at the northern end of the IRL system. The USGS Nonindigenous Aquatic Species
(NAS) program considers M. coccopoma to be established in the Volusia County portions of the
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Megabalanus coccopoma grows to around 5 cm in height and width.
Tibbetts (2007) reports that non-native M. coccopoma from South
Carolina attain a body mass 100 times greater than that of native barnacle species.
Collection information reported from Florida to date do not yet indicate the
presence of Megabalanus coccopoma in large numbers.
Details on reproduction in Megabalanus coccopoma remain unpublished.
Reproduction in nearly all barnacles employs outcrossing of neighboring adult
individuals as the norm, with individual animals occurring as simultaneous
hermaphrodites. Fertilization is internal, occurring through the deposit of
sperm into the mantle cavities of adjacent animals via an elongated
Details on larval development in Megabalanus coccopoma remain
unpublished. As with other barnacle species, M. coccopoma larvae
progress through several sequential nauplius stages and one cypris larval stages prior to
settling to suitable hard substrata to spend the rest of their lives as sessile
Cool water temperatures appear capable of limiting the distribution of this
tropical species. A 1982-1983 El Niño event allowed a brief northern range
expansion along the southern California coast into ephemeral warm water off of
San Diego (Newman and McConnaughey 1987).
Megabalanus coccopoma appears to favor high salinity conditions
(Kerckhof 2002). If 2006 reports of the species from estuarine waters near
Port St. Lucie, Florida, are valid, however, then M. coccopoma also
appears capable of inhabiting more brackish environments.
Like other acorn barnacles, Megabalanus coccopoma filter feeds when
submerged by means of a set of extensible sieving appendages called cirri
(barnacles belong to infraclass Cirripedia). The extended cirri are oriented
perpendicular to the general flow direction and varying food concentrations and
water velocities can elicit different patterns and rates of movement of the
cirri to maximize particle intake (LaBarbera 1984, Crisp and Bourget 1985).
Megabalanus coccopoma occur alongside a number of different animal and
algal taxa that comprise hard fouling intertidal communities, although none of
these associations are likely to be obligate.
Megabalanus coccopoma is native to the eastern Pacific, historically
known to occur from Baja California (occassionally as far north as San Diego)
through Central and South America southern Equador.
M. coccopoma was reported as a non-native species established in
southern Brazil in the late 1980s and along the coast of Belgium in 2002
(Newman and McConnaughey 1987, Kerckhof 2002). The species was found in
Louisiana in 2002, and from Florida, Georgia, and South Carolina in 2006.
Ship hull fouling and ballast water transport are the most probable
Potential to Compete With Natives
If Megabalanus coccopoma begins to occur in consistently large numbers
within its non-native range in Florida and elsewhere, it would be expected to
compete with other intertidal hardbottom organisms for space and also possibly
with a variety of filter-feeding animals for food.
Young (1994) suggests M. coccopoma, now established along southern
Brazil, may outcompete the native congeneric barnacle, M. tintinnabulum.
Possible Economic Consequences of Invasion
Boat hulls props, and drive shafts, coastal navigation buoys, and other
submerged man-made hard surfaces are readily colonized by settling
Megabalanus coccopoma (Kerckhof, 2002). If the
species becomes established, costs associated with removing animals from such
structures may be significant.
Factors such as gregarious settlement, rapid growth, and large size suggest
M. coccopoma has the potential to become an economically important
nuisance species in Florida.
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Florida Wildlife. 2007. New, bigger barnacle discovered on Florida's East
Coast. Florida Wildlife 2007:13.
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overview of the species and recent evolutions, with emphasis on exotic species.
Bulletin van het Koninklijk Belgisch Instituut voor Natuurwetenschappen.
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suspension feeding animals. American Zoology 24:71-84.
McPherson B.F., Sonntag W.H., and M. Sabanskas. 1984. Fouling Community of the
Loxahatchee River Estuary, Florida, 1980-81. Estuaries 7:149-157.
Newman, W.A., and R.R. McConnaughey. 1987. A tropical eastern Pacific barnacle,
Megabalanus coccopoma (Darwin), in southern California, following El
Ni—o 1982-83. Pacific Science 41:31-36.
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Polychaete Species in the South Atlantic Bight . NOAA's National Sea Grant
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