The checkered nerite, Nerita tessellata, is a common intertidal
gastropod in southeast Florida. The snail is named for the black
and white checkered pattern on the shell, which covers a series
of coarse irregular spiral ridges on 4-5 whorls (Andrews 1994, Abbott
& Morris 1995, Bovbjerg 1984). The calcareous operculum is black,
closing around an aperture which displays numerous small teeth on
the interior of the inner and outer lips (Abbott & Morris 1995).
Members of this family (Neritidae) are also characterized by a small,
pointed hook at the end of the operculum (Abbott & Morris 1995).
Potentially Misidentified Species
Several other species of small gastropods occur in the intertidal areas
of the IRL where N. tessellata is abundant. Of these, the
two species that are most closely related to the checkered nerite
are: the Antillean nerite, Nerita fulgurans; and the four-tooth
nerite, N. versicolor. Both species are roughly the same
size as N. tessellata.
The shell of the Antillean nerite is dark gray
to yellowish gray, black, or mottled brown (Andrews 1994, Abbott
& Morris 1995). Markings are occasional and generally less distinct
than N. tessellata, but the shell has the same 4-5 whorls.
The aperture is more prominently toothed than the checkered nerite,
with two larger teeth on the inside of the outer tip and the inner
lip toothed throughout (Andrews 1994). Unlike the checkered nerite,
the operculum of N. fulgurans is yellowish gray. This species
is reported to prefer brackish waters (Abbott & Morris 1995).
The shell of the four-tooth nerite
is slightly more elongate than N. tessellata or N.
fulgurans (Andrews 1994), with about four whorls (Abbott &
Morris 1995). Coarse spiral threads mark the outside of the shell,
which is dirty white with red and black spots or bars. The outer
lip is toothed within, and the interior of the inner lip bears four
prominent teeth. Fine dimples are present on the dark gray operculum
(Abbott & Morris 1995). The four-tooth nerite is reported to
be most abundant in oceanic rocky intertidal areas (Andrews 1994).
In some locations where N. tessellata and N. versicolor
occur together, the four-tooth nerite retreats farther from the
water line; whereas, the checkered nerite can be found at the air-water
interface (Bovbjerg 1984).
HABITAT AND DISTRIBUTION
Regional Occurrence & Habitat Preference
The range of N. tessellata extends
from southern Florida to Brazil and Bermuda, with rare sightings
in northern Florida (Andrews 1994, Russell 1941). It is a rocky
intertidal species that is most abundant at or just below the water
line, though seldom deeper than 0.5 m (Bovbjerg 1984). Migration
occurs over the course of the day to maintain this position with
the tidal cycle.
Though little information exists on the distribution of the checkered
nerite in the IRL, it is most likely more abundant in the southern
areas of the lagoon. Populations can be found in rocky shorelines
near inlets, jetty rocks and seawalls.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
The checkered nerite has a length of approximately 1.9 to 2.5 cm
(Andrews 1994). The average shell length for populations in the
Florida Keys was measured at 1.9 cm (Bovbjerg 1984).
Abundance estimates for populations of N. tessellata in
the IRL are unknown. However, checkered nerites have been recorded
at densities of: 24 m-2 in Pigeon Key, Florida (Bovbjerg
1984); 40 m-2 in Key Largo, Florida (Kolipinski 1964);
and between 93 and 220 m-2 in Barbados (Hughes 1971,
Like other species of Nerita,
N. tessellata copulates at night. The male transfers sperm-filled
sacs, called spermatophores, to the female via a gelatinous tube
that is extended from the tip of the penis into the mantle cavity
of the female (Chislett 1969). Mature females continually carry
spermatophores (Chislett 1969). Once the eggs are fertilized, the
female deposits them in water-filled depressions of rocks or other
sheltered areas around the mean tide level where they are somewhat
protected from direct sun exposure until hatching
(Hughes1971). The reproductive season seems to be tied somewhat to location. Populations in Florida
have been reported to spawn mainly in the summer months (Kolipinski
1964); whereas, those in Barbados are reproductively active year-round
(Hughes 1971). Individuals are sexually mature at a length of about
1.7 cm (Kolipinski 1964).
Embryology / Larval Development
The 1mm long egg capsules of N. tessellata
are oval and covered with calcium carbonate bumps (Andrews 1935).
Each capsule contains approximately 111 eggs, which hatch after
about 21 days (Kolipinski 1964). Like many other mollusks, the checkered
nerite reproduces via a planktonic larva called a veliger (Kolipinski
1964). These larvae remain in the water column until they reach
the final stage, or pediveliger, at which time they search for a
suitable location to settle and metamorphose into juvenile snails.
The average female N. tessellata lays about 160 egg capsules
per year (Kolipinski 1964).
Temperature & Salinity
Little information exists describing the environmental tolerances
of N. tessellata. However, the distribution and range of
most populations suggests the species prefers oceanic to highly
saline brackish, warm coastal waters. Lewis (1960, 1963) suggested
that the intertidal zonation patterns of the checkered nerite were
related to its evaporative cooling abilities at tropical and subtropical
The checkered nerite
feeds mostly at night, grazing along rocks at lateral distances
of up to 23 m over a 2-day period (Bovbjerg 1984). Microscopic organisms
composing the biofilm (slime layer) are the dominant food source
scraped from rock surfaces, including: algae, detritus, flagellates,
diatoms and nematodes (Bovbjerg 1984).
Documented accounts of predation on N.
tessellata are scarce. However, checkered nerites are likely
preyed upon by a variety of birds, fishes and invertebrates. In
particular, crabs, pufferfishes and the common octopus, Octopus
vulgaris, have been cited as dominant predators of neritid
snails (Bovbjerg 1984, Vermeij 1978).
No known obligate associations exist for N. tessellata.
However, checkered nerites are associated with several organisms
common to rocky intertidal habitats. For extensive lists of species
found in this habitat and others throughout the IRL, please refer
to the links at the left of this page.
No information is available at this time
Abbott, RT & PA Morris. 1995.
A field guide to shells: Atlantic and Gulf coasts and the West
Indies, 4th edition. Houghton Mifflin Co. Boston, MA. USA.
Andrews, EA. 1935. The egg capsules of certain
Neritidae. J. Morph. 57: 31-59.
Andrews, J. 1994. A field guide to shells
of the Florida coast. Gulf Publishing Co. Houston, Texas. USA.
Bovbjerg, RV. 1984. Habitat selection in two
intertidal snails, genus Nerita. Bull. Mar. Sci. 34: 185-196.
Chislett, GR. 1969. Comparative aspects
of the ecology of three Nerita (Mollusca: Gastropoda) species
from different locations in Barbados. Master's Thesis. McGill
University. Montreal, Quebec. Canada.
Hughes, RN. 1971. Ecological energetic of
Nerita (Archaeogastropoda, Neritacea) populations on Barbados,
West Indies. Mar. Biol. 11: 12-22.
Kolipinski, MC. 1964. The life history,
growth and ecology of four intertidal gastropods. PhD Dissertation.
University of Miami. Miami, FL. USA.
Lewis, JB. 1960. The fauna of rocky shores
of Barbados, West Indies. Can. J. Zool. 28: 391-435.
Lewis, JB. 1963. Environmental and tissue
temperatures of some tropical intertidal marine animals. Biol.
Bull. 124: 277-284.
McLean, RF. 1967. Measurements of beachrock
erosion by some tropical marine gastropods. Bull. Mar. Sci.
Russell, HD. 1941. The recent mollusks of
the family Neritidae of the western Atlantic. Bull. Mus. Comp.
Zool. Harvard. 88: 347-404.
Vermeij, GJ. 1978. Biogeography and adaptation,
patterns of marine life. Harvard University Press. Cambridge.