The family Calpytraeidae is made up of three
genera: Crepidula (slipper shells), Crucibulum (cup and saucer
shells) and Calyptraea (hat shells). All of the species have
limpet-shaped shells with an internal shelly septum. The genera are
distinguished by shell morphology. In Crepidula the shell apex is
directed posteriorly and the internal septum is a flat shelf that attaches along
both sides of the shell. In Crucibulum the shell is conical with a
central apex and a cup-shaped internal septum. In Calyptraea the shell
is conical with a central apex but the internal shelly septum is a coiled ramp.
Shells are often not diagnostic on the species level. Cryptic species often
co-occur but they can usually be distinguished on the basis of developmental
characters and body pigmentation. There are 6 species of Crepidula, one
Crucibulum and one:
Calyptraea reported from Florida: Crepidula ustulatulina, C. depressa, C. atrasolea, C. aculeata, C. maculosa and
C. fornicata, Crucibulum auriculum, and Calyptraea centralis.
The taxonomy of Crepidula aculeata,
as it stands, is comprised of at least 8 species that are morphologically
indistinguishable as adults. However only one species, the true C. aculeata,
occurs in Florida. Externally, the shell is relatively flattened and quite
coiled compared to the other Crepidula species, and is the only
Crepidula with spines. External shell sculpture ranges from widely spaced
large scale-like plicate spines to tightly packed pointed granular bumps along
fine spiral ribs. Shell color ranges from overall cream with scattered brown
markings to solid chocolate brown, sometimes with a pale streak. The markings
are sometimes speckled, and often streaky. The anterior margin of the septum is
indented medially and notched on the animal's left. A distinct but small medial
ridge or crease extends from medial indentation to posterior shell margin. The
small lunar muscle scar on the animal's right side anterior to the shelf is
often more deeply indented than in other Crepidula species. The shell is
distinctly coiled with about one single whorl after the protoconch-teleoconch
boundary. The apex is appressed, usually occurs slightly above the posterior
shell margin on the right, and is not excavated. Maximum shell length, 3.2 cm.
The head, neck, foot and mantle are
cream but there is matt black marbled pigmentation along the edge of the foot.
Large yellow or orange pigment splotches are scattered along the neck lappets
and concentrated on the lips and tentacles. Black pigment also occurs on the
dorsal side of the head and neck. The intensity of all pigmentation varies and
some animals have almost no black pigment. The black pigment is retained in
preserved or fixed material but the yellow and orange markings are lost.
Potentially Misidentified Species
Crepidula aculeata is part of a cryptic species complex which is currently
under revision (Collin, In Prep). There are at least 8 distinct species
world-wide, which cannot be distinguished from one another on the basis of adult
morphology, although they can be distinguished through the use of DNA sequencing
and developmental data.
In Florida, There are no other Crepidula species
with spiny shells and so much shell coiling; thus, C. aculeata is
unlikely to be confused with any other species in Florida.
HABITAT AND DISTRIBUTION
The known distribution of this species includes
the east and west coasts of Florida, the Florida Keys, Yucatan, and the
Bahamas. Shells with a similar morphology have been found from as far north as
North Carolina and probably also belong to this species.
Crepidula aculeata occurs throughout the Indian River Lagoon.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Maximum shell length is 3.2 cm.
Crawls. There is no free swimming stage in hatchlings.
All calyptraeids are protandric hermaphrodites:
small, young animals are males that later change to females as they grow.
All species copulate. Females are able to store sperm for several months.
The females deposit eggs into transparent capsules that they brood between the
neck and the propodium. In some species, swimming larvae hatch from the
capsules; in others, benthic juveniles crawl away from the capsules.
Crepidula aculeata brood transparent egg capsules typical of all
calyptraeids between the neck and the propodium. The 20-30 large yolky eggs in
each capsule all develop directly into crawling juveniles. Eggs are about 380
microns in diameter and the juveniles hatch at a shell length of about 840
Species in all three genera of the Calyptraeidae are suspension feeders. They collect phytoplankton on mucus covering the gills. Phytoplankton are then transported to the mouth on a mucus string along the
dorsal right side of the neck. The string is drawn into the mouth by the radula.
Crepidula aculeata are common on rocks and other hard debris in the shallow subtidal. This species can also sometimes be found on the carapaces of horseshoe crabs. They occur from the low intertidal to a depth of at least 60 meters.
No information is available at this time
Collin, R. 2002. Another last word on Crepidula
convexa and a description of C. ustulatulina sp. nov. (Gastropoda:
Calyptraeidae) from the Gulf of Mexico. Bulletin of Marine Science 70: 177-184.
Collin, R. 2001. The effects of mode of development
on phylogoegraphy and population structure of North Atlantic Crepidula
(Gastropoda: Calyptraeidae). Molecular Ecology. 10: 2249-2262.
[This includes, C. atrasolea, C. depressa and C.
Collin, R. 2000. Phylogeny of the Crepidula
plana (Gastropoda: Calyptraeidea) cryptic species complex in North
America. Canadian Journal of Zoology. 78: 1500-1514. [This includes C.
depressa and C. atrasolea]