Longnose Spider Crab

Libinia dubia

Summary 4

Libinia dubia, the longnose spider crab, is a species of crab in the family Epialtidae. It is found in shallow waters on the eastern coast of North America.

Description 5

Libinia dubia belongs to a group of brachyuran crabs commonly referred to as decorator crabs. Using hooked, Velcro-like setae on the surface of the carapace, the crabs attach bits of algae and invertebrates for camouflage. This behavior is most common in juveniles, and the shells of adult crabs are usually found clean. Under the decorative covering, the carapace of L. dubia is rounded, bearing approximately six spines down either side and along the median line on the dorsal surface (eg. Corrington 1927). A forked rostrum extends between the eyes, and the overall color of the body is yellowish to brown (Voss 1980). Long, thin walking legs originating from the rounded body give the crab the spidery appearance for which it is named. These legs culminate in curved points, allowing the crab to cling to various surfaces like rocks and jellyfishes (Ruppert & Fox 1988).

Size 6

Information on the lifespan and adult growth patterns of L. dubia is lacking. However, the average carapace diameter for mature crabs is 6 to 10 cm (Corrington 1927, Ruppert & Fox 1988), with the length of walking legs adding considerably to the total body size. As with most species, growth rates are likely dependent on food availability, environmental conditions and other factors.

Look alikes 7

Three species of Libinia inhabit the coastal and estuarine waters of the Western Atlantic and Caribbean Oceans: L. dubia; the portly spider crab, L. emarginata; and the seagrass spider crab, L. erinacea. The color and shape of all species are similar, and discrimination between juvenile specimens can be difficult. However, Libinia dubia and L. emarginata are distinguished by the number of dorsal median spines, bearing six and nine, respectively (Abele & Kim 1986). The maximum size of the portly spider crab is also slightly larger than that of L. dubia (Ruppert & Fox 1988). The rostrum of young seagrass spider crabs forks more deeply than L. dubia, and the horns curve toward one another (Abele & Kim 1986). II .

Reproduction 8

Like other brachyuran crabs, sex can be determined in Libinia dubia by examining the abdomen. In females, it is broader and can be tightly flexed to hold the egg mass, or sponge (eg. Ruppert et al. 2004). On average, females are also slightly smaller than males (O'Brien et al. 1999, Tunberg & Reed 2004). As with most decapod crustaceans, fertilization occurs during copulation. The male transfers sperm-filled cases, called spermatophores, to the female. After the eggs are fertilized, the female broods them on her abdomen until hatching.

Distribution 9

Virginian, south side of Cape Cod, extending northward of the subprovince limit, including Cobscook Bay.

Link to Access Genomic Data 10


Sources and Credits

  1. (c) Alan Cressler, all rights reserved, uploaded by matbio, http://www.discoverlife.org/mp/20p?see=I_AMC7899&res=640
  2. (c) josenunez, some rights reserved (CC BY-NC-ND), uploaded by Jose Nunez, http://www.inaturalist.org/photos/1101114
  3. (c) David Remsen, some rights reserved (CC BY-NC), https://www.flickr.com/photos/dremsen/15166393159/
  4. Adapted by matbio from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Libinia_dubia
  5. Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526329
  6. (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526335
  7. Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526332
  8. Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526334
  9. Adapted by matbio from a work by (c) WoRMS for SMEBD, some rights reserved (CC BY), http://eol.org/data_objects/29749240
  10. (c) Emily Rose Sharkey, all rights reserved

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