Potentially Misidentified Species:
Despite the convergent shell morphology of a number of unrelated IRL gastropod
taxa, Siphonaria pectinata should be fairly easy to identify. Several
keyhole limpets of the genus Diodora occur in the IRL and all of these are readily
discernable by the presence of the 'keyhole' opening at the apex of the shell.
II. HABITAT AND DISTRIBUTION
Siphonaria pectinata is widespread throughout the Mediterranean and Atlantic
basin north of the equator. It is a common rocky high intertidal inhabitant on
the Florida east coast and Florida Keys (Voss 1959, Baker et al. 2004).
In east Florida Siphonaria pectinata is restricted primarily to rocky
intertidal habitats. To the north and south of the IRL, various types of beach
rock provide suitable habitat (Craig et al. 1969). Within the IRL region,
however, the majority of rocky intertidal sites are manmade habitats such as
inlet rock jetties, seawalls, and concrete pier and bridge pilings. In light
of its dependence on manmade hard substrate, Baker et al. (2004) refer to S.
pectinaria in Florida as an "urban" species.
In the IRL S. pectinaria is a common to abundant inhabitant of the high
inertidal rock inlet jetties that connect the estuary to the Atlantic Ocean.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
The shell length of Siphonaria pectinata can reach about 30 mm, but most
individuals only grow half as large (Baker et al. 2004).
Where suitable habitat can be found Siphonaria pectinata can be among the most
abundant gastropods of the high intertidal on Florida's east coast. Whitney
Laboratory in St. Augustine lists the species as common,
indicating that 10-50 individuals can easily be collected from the field in a
day. The species is similarly perennially abundant on the rock jetties of Fort
Pierce Inlet of the IRL in St. Lucie County.
A study by Ocana and Emson (1999) reveals aspects of the reproductive biology
of S. pectinata populations from Gibraltar that may hold for animals in
Florida. Maturation occurred between 6-12 months of age when individuals
attained a shell length of 5-6 mm. Spawning occurred from March to June, with
activity peaking in the second half of this timeframe. Spawning and egg
deposit appeared to be less common at exposed sites relative to protected
Small oval ribbons containing several hundred (and up to one-thousand) eggs in
a gelatinous matrix are deposited in shallow depressions, cracks and crevices,
usually away from home scars the limpets return to at low tide (Voss 1959, Ocana and Emson 1999).
Ocana and Emson (1999) report that fertilized eggs took 14-21 days to develop
at ambient temperatures of 14-19ºC. Larvae hatch out as free-swimming veligers
exhibiting a planktonic larval stage of short duration. Voss (1959) indicates
this to be a primitive trait in pulmonate gastropods.
IV. PHYSICAL TOLERANCES
High temperature stress is a distinct possibility in the upper intertidal
during periods of exposure and animals have evolved a number ways to reduce
thermal stress. Siphonaria pectinata returns to its home scar to wait out
periods of exposure to air and potential lethal temperatures (Williams and
Morritt 1995). When air temperatures are not extreme S. pectinata
may also exhibit a behavior known as 'mushrooming,' i.e., lifting the shell to expose
the foot and other tissue, possibly as a means of enhancing evaporative cooling
(Lowell 1984). There exists potential conflict in intertidal organisms
between the need to combat desiccation and the need to regulate temperature,
and suggests water conservation is often the overriding concern.
Experimental work by McAlister and Fisher (1968) suggest that Siphonaria pectinata is capable of tolerating salinities between 20 and 40 ppt.
Animals exposed to salinities above and below this range were unable to attach
to hard surfaces. In addition, no animals survived more than 24 hours after exposure to
these extremes. The authors suggest that S. pectinata clamps down on
the substratum in response to exposure to salinity extremes, and maintains
muscle tonus for extended periods to avoid coming into contact with the extreme
Striped falselimpets are well-adapted for life in the high intertidal.
McAlister and Fisher (1968) demonstrated that when Siphonaria pectinata are
clamped onto a hard substratum they can withstand desiccation for up to 72
V. COMMUNITY ECOLOGY
Siphonaria pectinata is a grazer that forages short distances from its home scar
in the rocky intertidal, scraping epiphytic (plant) material and from hard surfaces
with its radula. Voss (1959) suggested the organism fed on encrusting
material, but more recent studies indicates that S. pectinata instead
grazes superficial, soft algae (including spores and emerging germlings) with
its fine-toothed radula (Ocana and Fa 2003).
S. pectinata co-occurs with other rocky intertidal species. In Florida,
this assemblage includes several species of barnacles and littorinid snails.
VI. INVASION INFORMATION
The striped falselimpet has been present in Florida waters since the 19th
century. Morrison (1963, 1972) believed the species was introduced from the
Mediterranean. Carlton (1992), however, suggests the western Atlantic to have been the
source of invasion. In both cases accidental transport as fouling organisms on
ship hulls is the putative vector. Consensus as to the origins of the species
is lacking, however, and it is considered to be cryptogenic by many
authorities. (Baker et al. 2004).
Potential to Compete With Natives:
Rocky intertidal marine communities occupy a classically space-limited
environment. Competition between Siphonaria pectinata and native species would
likely be for living spaces as well as food. The apparent dietary
semi-specialization of S. pectinata on superficial, soft microalgae may
serve to reduce competition with other grazers that consume harder encrusting
material (Ocana and Fa 2003).
In some instances, S. pectinata may function as an ecosystem engineer.
Craig et al. (1969) reported that grazing by this species facilitates the
formation of secondary solution features characteristic of south Florida beach
rock by exposing new rock surfaces to biochemical erosion.
Possible Economic Consequences of Invasion:
The economic impacts of striped falselimpets has been deemed negligible in the
Tampa Bay estuary system (Baker et al. 2004), and a similar assumption may be
made with regard to the IRL and Florida east coast where the species occurs.
Baker P., Baker S.M., and Jon Fajans. 2004. Nonindigenous marine species in
the greater Tampa Bay ecosystem. Tampa Bay Estuary Program Technical
Publication 02-04. 131p.
Biskupiak J.E. and C.M. Ireland. 1983. Pectinatone, a new antibiotic from the
mollusc Siphonaria pectinata. Tetrahedron Letters 24:3055-3058.
Carlton J.T. 1992. Introduced marine and estuarine mollusks of North America:
An end-of-the-20th-Century perspective. Journal of Shellfish Research
Craig A.K., Dobkin S., Grimm R.B., and J.B. Davidson. 1969. The Gastropod,
Siphonaria pectinata: a Factor in Destruction of Beach Rock. American
Lowell R.B. 1984. Desiccation of intertidal limpets: Effects of shell size, fit
to substratum, and shape. Journal of Marine Biology and Ecology 77:197-207.
McAlister R.O. and F.M. Fisher. 1968. Responses of the false limpet,
Siphonaria pectinata Linnaeus (Gastropoda, Pulmonata) to osmotic stress.
Biological Bulletin 134:96-117.
Morrison J.P.E. 1963. Notes on American Siphonaria. Annual Reports of
the American Malacological Union 1963:7-9.
Morrison J.P.E. 1972. Mediterranean Siphonaria: West and east-old and new.
Ocana T.M.J., and R.H. Emson. 1999. Maturation, Spawning and Development in
Siphonaria pectinata Linnaeus (Gastropoda: Pulmonata) at Gibraltar.
Journal of Molecular Studies 65:185-193.
Ocana T. and D.A. Fa. 2003. Microalgal availability and consumption by
Siphonaria pectinata (L., 1758) on a rock shore. Boletin del Instituto
Espanol de Oceanografia 2003:1-4.
Voss, Nancy A. 1959. Studies on the pulmonate gastropod Siphonaria pectinata
(Linnaeus) from the southeast coast of Florida. Bulletin of Marine Science 9:84-99.
Williams G.A. and D. Morritt. 1995. Habitat partitioning and thermal tolerance
in a tropical limpet, Cellana grata. Marine Ecology Progress Series
J. Masterson, Smithsonian Marine Station
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Page last updated: October 5, 2007