Species Description: The flyspeck cerith, Cerithium muscarum, is a small gastropod mollusc of the family Cerithiidae. The elongate shell has 9-10 distinct whorls and a sharp apex. Nine to 11 pronounced nodulose axial ribs, crossed by dotted and dashed spiral lines, cover each whorl. The background shell color is light tan to slate to light brown, and the small 'fly specks' that form the spiral rows are chestnut brown. The aperture is oval and oblique, while the canal is short and turned to the left (Abbot and Morris 1995, Baily-Matthews Shell Museum undated).
Potentially Misidentified Species: Although there are several similarly sized and shaped ceriths that co-occur with Cerithium muscarum, the whorl count, the robust radial ribs, and the distinct color pattern should allow positive identification of specimens to species.
Regional Occurrence: Rosenberg (2005) reports flyspeck ceriths occur from a latitude of 35° to 16.5° north latitude and from 97° to 76° west longitude. This distribution spans from North Carolina south throughout both Florida coasts, throughout the Gulf of Mexico and in much of the Caribbean.
Abbot and Morris (1995) report a somewhat more restricted distribution, including Bermuda, and the Atlantic coast of the Americas from south Florida to Brazil.
IRL Distribution: Cerithium muscarum occurs throughout the IRL system.
Age, Size, Lifespan: Rosenberg (2005) notes the maximum reported size for the species is 26 mm. Houbrick (1974) indicates the life span is approximately 1 year.
Abundance: Young and Young (1977) list Cerithium muscarum as among the top 10 macrobenthic community dominants in the Indian River Lagoon seagrass habitats they surveyed. This is the most common of the Florida ceriths.
Reproduction: Reproduction in Cerithium is sexual. The sexes are separate and fertilization is internal although males lack a penis (Cannon 1975). After copulation, females deposit a stringy egg mass which they attach to benthic substrata (Houbrick 1970).
Embryology: Cerithium muscarum lack planktonic larvae, a trait they share with some other euryhaline shallow water species but one that is not common to the entire genus (Houbrick 1970, Cannon 1975).
Juveniles grow to adults in a few months (Houbrick 1974).
Temperature: This gastropod occurs from North Carolina south to the Caribbean, indicating a moderate degree of thermal tolerance. Salinity and temperature tolerance experiments by Murray and Wingard (2006) yielded high survival rates at temperatures as high as 34°C.
Salinity: Collection records maintained by the NOAA National Benthic Inventory (NBI undated) indicate the flyspeck cerith is euryhaline, with most collections occurring at salinities ranging from 18.3 ppt to more than 41 ppt. Salinity and temperature tolerance experiments by Murray and Wingard (2006) reveal that survivorship and reproduction are both enhanced under hypersaline (57-62 ppt) conditions.
Trophic Mode: Captive-reared Cerithium muscarum consume sand and surface deposits, epiphytic algae, and seagrass detritus, believed to be reflective of the typical natural diet of the species (Houbrick 1974).
Predators: Several species of crabs prey upon Cerithium muscarum, including those of genera Callinectes, Menippe, and Libinia. Carnivorous gastropods known to consume C. muscarum include Melongena corona, Busycon contrarium, Fasiolaria tulipa, and Pleuroploca gigantea, and several natacid and muricid snails are putative predators as well. Stingrays and horseshoe crabs (Limulus polyphemus) are suspected predators (Houbrick 1974).
Parasites: Hutton and Sogandaraes-Bernal (1959) identified larval tremetodes (Mesotephanus appendiculatoides) in Cerithium muscarum. In later stages of its life cycle, this parasite encysts in the muscles of mullet (Mugil spp.) and matures in the intestines of a variety of megafauna including pelicans, cormorants, and raccoons. Cercaria sp. has also been reported as a parasite of C. muscarum (Hutton 1964).
Associated Species: Rey and Stoner (1984) report a small fraction (around 2%) of the IRL sea hare (Aplysia brasiliana) egg masses they examined had associated Cerithium muscarum on them. Houbrick (1974) reports that small slipper shells (Crepidula) are often found attached to the shells of C. muscarum.
Habitats: The flyspeck cerith is a shallow intertidal to subtidal species, typically occurring at 1 m or less (Rosenberg 2005), although NOAA NBI collection records indicate specimens have been collected from as deep as 2.6 m. It can be found in seagrass meadows and on unvegetated soft sediments.
Activity Time: Howard (1987) conducted day-night comparisons of the epifauna of IRL seagrass beds. The author found that adult Cerithium muscarum were more abundant in the upper canopy at night while juveniles showed no preference for day or night.
Special Status: None
Economic/Ecological Importance: The empty shells of dead Cerithium muscarum are an important habitat resource for small hermit crabs such as those of family Paguridae. Tunberg et al. (1994) report that shells from C. muscarum, Modulus modulus, and Nassarius vibex accounted for 94% of the shells utilized by Indian River Lagoon Pagurus maclaughlinae.
Abbot RT and PA Morris. 1995. Shells of the Atlantic and Gulf Coasts and the West Indies. Peterson Field Guides. Houghton Mifflin Company, NY. 350 p.
Bailey-Matthews Shell Museum. Undated. Cerithium muscarym species profile. Available online.
Cannon LRG. 1975. On the reproductive biology of Cerithium moniliferum Kiener (Gastropoda, Cerithiidae) at Heron Island, Great Barrier Reef. Pacific Science 29:353-359.
Houbrick JR. 1970. Reproduction and development in Florida Cerithium. Page 74 in: Annual report of the American Malacological Union, Inc. for 1970.
Houbrick R. 1974. Growth studies on the genus Cerithium (Gastropoda: Prosobranchia) with notes on ecology and microhabitats. Nautilus 88:14-27.
Howard RK. 1987. Diel variation in the abundance of epifauna associated with seagrasses of the Indian River, Florida, USA. Marine Biology 96:137-142.
Hutton RF. 1964. A second list of parasites from marine and coastal animals of Florida. Transactions of the American Microscopical Society 83:439 -447.
Hutton RF and F Sogandares-Bernal. 1959. Further notes on Trematoda encysted in Florida mullets. Quarterly Journal of the Florida Academy of Science 21:329-334.
Murray JB and GL Wingard. 2006. Salinity and temperature tolerance experiments on selected Florida Bay mollusks. US Geological Survey Open File Report 2006-1026. Us Department of Interior/US Geological Survey. 59 p.
NOAA National Benthic Inventory (NBI). Undated. Cerithium muscarum collection information. Available online.
Rey JR and AW Stoner. 1984. Macroinvertebrate associations on the egg masses of the sea hare, Aplysia brasiliana Rang (Gastropoda: Opisthobranchia). Estuaries:158-164.
Rosenberg G. 2005. Malacolog 4.1.0: A database of western Atlantic marine Mollusca. WWW database (version 4.1.0). Available online.
Tunberg BG, Nelson WG, and G Smith. 1994. Population ecology of Pagurus maclaughlinae Garcia-Gomez (Decapoda: Anomura: Paguridae) in the Indian River Lagoon, Florida. Journal of Crustacean Biology 14:686-699.
Young DK and MW Young. 1977. Community structure of the macrobenthos associated with seagrass of the Indian River estuary, Florida, p. 359- 381 in: B. C. Coull (ed.). Ecology of Marine Benthos. University of South Carolina Press. Columbia, South Carolina.