L. emarginata is triangular in outline, with a carapace about 4 in (100 mm) long and a leg span of 12 inches (300 mm). The whole crab is khaki, and the carapace is covered in spines and tubercles, and is often clothed in debris and small invertebrates.
Mating takes place, and eggs are produced from June to September. The eggs are initially a bright orange-red, but turn brown during development, which takes around 25 days. The eggs then hatch as zoea larvae, and the female can produce another brood of eggs within 12 hours, unlike many other crabs, where females only mate directly after molting.
L. emarginata is very similar to Libinia dubia with which it is largely sympatric. They can be told apart by examining the row of spines along the center of the carapace: in L. emarginata there are nine, while in L. dubia there are only six. Also, the rostrum of L. dubia is more deeply forked than that of L. emarginata.
Ecology and behavior
Unusually for crabs, L. emarginata preferentially walks forwards, rather than sideways, although they are also capable of sidelong movement.
|External identifiers for Libinia emarginata|
- ^ "Libinia emarginata Leach, 1815". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=98455. Retrieved November 13, 2011.
- ^ Peter K. L. Ng, Danièle Guinot & Peter J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology 17: 1–286. http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf.
- ^ Harriet Perry & Kirsten Larsen (2004). "A Picture Guide to Shelf Invertebrates from the Northern Gulf of Mexico" (PDF). Gulf States Marine Fisheries Commission. http://www.gsmfc.org/seamap/picture_guide/Crabs/libinia%20emarginata.pdf.
- ^ a b c d Andrew J. Martinez & Candace Storm Martinez (2003). "Arthropods". Marine Life of the North Atlantic: Canada to New England. Aqua Quest Publications. pp. 144–175. ISBN 9781881652328.
- ^ a b c Alice Jane Lippson & Robert L. Lippson (2006). "Crustaceans of the shallows". Life in the Chesapeake Bay (3rd ed.). JHU Press. pp. 153–158. ISBN 9780801883378.
- ^ a b Gertrude W. Hinsch (1968). "Reproductive behavior in the spider crab, Libinia emarginata (L.)". The Biological Bulletin 135 (2): 273–278. http://www.biolbull.org/cgi/content/abstract/135/2/273.
- ^ John C. Aldrich (1976). "The spider crab Libinia emarginata Leach, 1815 (Decapoda Brachyura), and the starfish, an unsuitable predator but a cooperative prey". Crustaceana 31 (2): 151–156. doi:10.1163/156854076X00189. http://www.jstor.org/stable/20103088.
- ^ A. G. Vidal-Gadea & J. H. Belanger (2009). "Muscular anatomy of the legs of the forward walking crab, Libinia emarginata (Decapoda, Brachyura, Majoidea)". Arthropod Structure & Development 38 (3): 179–194. doi:10.1016/j.asd.2008.12.002. PMID 19166968.