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The mud crab, Dyspanopeus sayi, collected from empty whelk shells in a Louisiana salt marsh. Photo by Crabby Taxonomist, online at https://www.flickr.com/photos/ crabby_taxonomist.

Species Name: Dyspanopeus sayi Williams, 1966
Common Name: Say's Mud Crab
Synonymy: Neopanope sayi SI Smith, 1869
Neopanope texana nigrodigita Rathbun, 1934
Neopanope texana sayi SI Smith, 1869
Panopeus sayi SI Smith, 1869
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Arthropoda Malacostraca Decapoda Panopidae Dyspanopeus

    Species Description

    Dyspanopeus sayi is a member of the family Panopidae.

  2. HABITAT AND DISTRIBUTION

    Regional Occurrence

    Say's mud crab is endemic in the Western Atlantic Ocean from Canada to Florida (Mistri 2004) and has also been found in along the Eastern Atlantic coast.

    IRL Distribution

    Dyspanopeus sayi is found in the Indian River Lagoon.

  3. LIFE HISTORY AND POPULATION BIOLOGY

    Age, Size, Lifespan

    Individuals of Say's mud crab can live to a maximum of 2 years. Adults have a maximum carapace width of 30 mm and males reach maturity at the approximate size of 16 mm (Strieb et al. 1995). In Long Island Sound, males are reported to be more abundant than females.

    Abundance

    In Long Island Sound, the density of Dyspanopeus sayi in eelgrass beds is up to 225 individuals per m2 but in open areas they are more scarce, with densities of only 0.5 m2 (Strieb et al. 1995). Recruitment of juveniles between late August and early October increases the density of Say's mud crab by 3- to 4-fold depending upon the site.

    Reproduction

    Dyspanopeus sayi has separate sexes.

    Embryology

    There are three zoeal stages before the megalopa.

  4. PHYSICAL TOLERANCES

    No information is available at this time

  5. COMMUNITY ECOLOGY

    Trophic Mode

    Dyspanopeus sayi uses its large crusher claw to break open the shell of shallow water bivalves (Mistri 2004).

    Associated Species

    Say's mud crab takes refuge in colonies of mud-burrowing polychaetes to avoid predation by blue crabs (Heck and Hambrook 2008).

  6. ADDITIONAL INFORMATION

    Fishery

    Because Callinectes ornatus occupies the same habitats as the commercial species, C. sapidus, it is impacted by the crab fishery along western Atlantic coast (Hsueh et al. 1992).

  7. REFERENCES

    Heck KL, Jr and JA Hambrook. 2008. Intraspecific interactions and risk predation for Dyspanopeus sayi (Decapoda: Xanthidae) living on polychaete (Filograna implexa, Serpulidae) colonies. Marine Ecology 12:243-250.

    ITIS. Integrated Taxonomic Information System. Available online.

    Mistri M. 2004. Predatory behavior and preference of a successful invader, the mud crab Dyspanopeus sayi (Panopeidae), on its bivalve prey. Journal of Experimental Marine Biology and Ecology 312:385-398.

    Strieb MD, Bricelli VM, and SI Bauer. 1995. Population biology of the mud crab, Dyspanopeus sayi, an important predator of juvenile bay scallops in Long Island (USA) eelgrass beds. Journal of Shellfish Research 14:347-357.

Report by: Melany P. Puglisi, Smithsonian Marine Station
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Page last updated: October 1, 2008

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