Caenogastropoda

Order LITTORINIMORPHA

Crepidula convexa - Convex Slipper Snail

Morphology: Small limpet. Shell convex and brown to purple in color. Shell apex rostrate. Maximum shell length 20 mm.

Distribution: East coast of North and Central America; introduced species in San Francisco and British Columbia

Habitat: Intertidal, found attached to hard substrates or seagrass.

Life History: Suspension-feeder. Undergo direct development.

Reference: Smithsonian Tropical Research Institute; Gosner plate 9

Crepidula plana - Eastern White Slipper Shell

Morphology: Limpet. Shell morphology highly variable; can be flat, convex, or concave. Shell white in color. Apex of shell generally not turned to either side. Shell can be up to 40 mm in length. 

Distribution: East coast of North and South America, from Canada to Brazil

Habitat: Attached to solid objects in intertidal and subtidal areas.

Life History: Suspension feeder. Males generally much smaller than females. Eggs brooded.

Reference: Mitchell Publications; Crowe p34

Echinolittorina placida - Interrupted Periwinkle

Morphology: Shell is 3-20mm. Dark brown aperture is oval and lacks a 'spout' at the blunt end (anterior canal). Variable color pattern, with diagonal zig-zags and broad black spiral band around each whorl.

Distribution: Yucatan Peninsula around the Gulf of Mexico to North Carolina.

Habtat: High intertidal.  Typically in crevices or sheltered areas.

Life History: Females spawn thousands of eggs, which hatch into swimming veliger larvae. Larval development occurs within approximately three weeks after which they settle on hard substrate.  Feed on microalgae from hard surfaces.

Reference: Natural History Museum, UK

Littorina irrorata - Marsh Periwinkle

Morphology: Shell is elongate, longer than it is wide, and dull grayish white with reddish brown on the ridges of the spiral.

Distribution: New York to Texas and the Gulf of Mexico.

Habitat: Found above the water line on or around vegetation; associated with salt marsh cordgrass Spartina alterniflora. 

Life History:  Herbivorous grazers feeling on algae, fungi and Spartina alterniflora.  Release egg masses from which larvae hatch.

Reference: Smithsonian Field Station at Ft. Pierce

Littorina littorea - Common Periwinkle

Morphology: Shell black or dark grey-brown, lighter toward apex and solid with five or six slightly turnid whorls. Spire prominent, pointed and last whorl may occupy 85% of shell height. 

Distribution: Northeastern Atlantic Ocean, Introduced to the Western Atlantic and Pacific coasts via ballast water.

Habitat: Rocky intertidal, sheltered sandy or muddy habitats, estuaries, and mud –flats. Tolerant of brackish water and up to a depth of 31m.

Life History: Omnivorous grazer, but feeds mostly on macroalgae. Reproduces through internal fertilization then sheds planktotrophic larvae into water, development occurs in 4-7 weeks.

Reference: Marine Species Identification Portal

Neverita duplicata - Moon Snail / Shark Eye

Morphology:  Flattened globular shape up to 90mm being of varying color, with a dark blue apex.

Distribution: From North Carolina to Texas, and in the Bahamas and Mexico.

Habitat: Found just off sandy shores below the tide line from 0 to 58 meters deep.

Life History: A predator that feeds on bivalves by drilling a hole and feeding on the inner tissue. Females lay egg masses surrounded by sand and mucus for protection.

Reference: Ashland University

Order NEOGASTROPODA

Busycon canaliculatum - Channeled Whelk

Morphology: Predatory gastropod.  Large, smooth, pear-shaped shell reaching 5 to 8 inches in length.  Large body whorl, straight siphonal canal and buff gray to light tan in color.   

Distribution: Cape Cod south to Northern Florida, also introduced into San Francisco Bay

Habitat: Sandy, shallow, intertidal or subtidal.  Buried or on top of sand or mud bottom.

Life History: Commercially valued. Carnivorous predators of other snails, clams or other shellfish.  After fertilization females produce distinct egg casings that are attached to hard substrate in the habitat.

Reference: Marine Biological Laboratory

Busycon carica - Knobbed Whelk

Morphology: Large marine gastropod with right-handed shell. Points along shoulder of shell and large siphonal opening. Shell color white to grey. Can grow to 30 cm in length.

Distribution: Cape Cod, Massachusetts to Cape Canaveral, Florida

Habitat: Estuaries and shallow coastal waters ( <50 m).

Life History: Carnivorous gastropod. Protandric hermaphrodite. 

Reference: Smithsonian Field Station at Ft. Pierce

Eupleura caudata - Thick-lip Drill

Morphology: Small gastropod. Shell brownish to grey in color. Ribbed shell with pointed spire. Can be distinguished from Atlantic oyster drill by examining the anterior canal. Thick-lipped oyster drills possess a longer canal with a narrower opening. Shell up to 20 mm in length.

Distribution: Northwest Atlantic

Habitat: Seagrass beds, oyster beds, and intertidal rocky bottoms

Life History: Predatory gastropod which uses a specialized radula and acid to create hole in shell of bivalves in order to feed. 

Reference: University of Rhode Island

Ilyanassa obsoleta - Eastern Mudsnail

Morphology: Intertidal prosobranch gastropod. Shell dark brown to black in color. Conical shell with 5-6 whorls present on spiral of shell. Maximum shell length approximately 28 mm.

Distribution: Both coasts of North America, from Labrador to northern Florida and Vancouver to central California (west coast introduced).

Habitat: Intertidal mud flats.

Life History: Important detritivore in muddy intertidal habitats. Hermaphroditic. Aggregate on mud flats in response to chemical cues from conspecifics.

Reference: Invertebrate Anatomy OnLine

Terebra dislocata - Common Auger

Morphology: Elongated shell with pointed spire. Spiral cord at the top of non- concave whorls that winds around 20-25 axial ribs. Colors can be off-white, tan or gray. 

Distribution: Virginia to Brazil 

Habitat: Silty sand beaches and creek bottoms 

Life History: Carnivorous, feeding on marine worms (commonly Golden acorn worm, Balanoglossus aurantiacus). Lacks a radula and poison gland found in other species.  

Reference: Seashore Animals of the Southeast

Urosalpinx cinerea - Oyster Drill

Morphology: Shell is knobby with rugged whorls and 5 rounded shoulders; yellow, orange, grey, or white with the occasional brown streak. Oval aperture with an open canal at the base.

Distribution: Northwestern Atlantic to southeastern Florida. 

Habitat: Intertidal/subtidal in estuaries and bays. Max depth ~15m. Also common on rocks and oyster reefs. Tolerates salinities as low as 13ppt.

Life History: Deposit or suspension feeders. Simultaneous hermaphrodites yet self-fertilization is prevented due to various morphological, physiological, or behavioral mechanisms. Vase shaped egg capsules are attached to hard substrate where they develop directly into benthic juveniles.

Reference: Smithsonian Marine Station at Ft. Pierce