Cancer Oregonensis Class: Malacostraca Order: Decapoda the Oregon Cancer Crab Section: Brachyura Family: Cancridae
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Phylum: Arthropoda, Crustacea Cancer oregonensis Class: Malacostraca Order: Decapoda The Oregon Cancer crab Section: Brachyura Family: Cancridae Taxonomy: Several synonyms are listed for Mouthparts: The mouth of decapod the species Cancer oregonensis (e.g. crustaceans is comprised of six pairs of Platycarcinus recurvidens, Trichocarcinus appendages including one pair of mandibles walkeri, Trichocera oregonensis), but the (on either side of the mouth), two pairs of most recent taxonomic debate involves the maxillae and three pairs of maxillipeds. The placement of this species in the recently maxillae and maxillipeds attach posterior to elevated genus, Glebocarcinus (Schweitzer the mouth and extend to cover it and the and Feldmann 2000). Molecular work does mandibles (Ruppert et al. 2004). The outer not always support the monophyly of cancrid maxillipeds in C. oregonensis have with genera (Harrison and Crespi 1999) and merus at antero-external angle (Fig. 2). although many researchers have switched to Carapace: Broadly oval, subelliptical the name Glebocarcinus oregonensis (e.g. (Rathbun 1930), widest at teeth 7–8 and Wicksten 2011), we follow the most current aerolated. Anterior-lateral and posterior- local intertidal guide that retains the name lateral margins do not form a distinct angle (C. Cancer oregonensis (Kuris et al. 2007). oregonensis, Rathbun 1930; Garth and Abbott 1980). Postero-lateral margin Description unbroken, entire and without teeth. Antero- Size: Individuals are usually not over 40 mm lateral and postero-lateral margins meet wide (Kozloff 1993). Large females are 47.1 without strong angle (Fig. 1). A characteristic mm wide and 36.5 mm long (Rathbun 1930). that separates the (proposed) genus The illustrated (Fig. 1) specimen is 15 mm Gleobcarcinus from other cancrid genera is a wide and 11 mm long. rounded carapace with length ¾ maximum Color: Carapace reddish dorsally, width, as seen in C. oregonensis (Schweitzer sometimes red, orange or yellow pigment and Feldmann 2000; Schram and Ng 2012). spots or bands, and flesh-colored ventrally. Frontal Area: Wide frontal area Walking legs (perepods) with dark red to (about 1/2 width of carapace). Five truncate black cheliped tips and can have bands of frontal teeth extend slightly beyond outer light color or red spots. There is considerable orbital angles. Three central teeth lobed (C. variation in color from yellow to orange with oregonensis, Rathbun 1930). Outer pair of carapaces that are sometimes gray (Jensen teeth form inner orbital angles (Fig. 3). 1995; Wicksten 2011). Teeth: 12–13 antero-lateral teeth, of General Morphology: The body of decapod which the first nine are prominent, equal, crustaceans can be divided into the large and forward curving. Teeth 3–9 have cephalothorax (fused head and thorax) and spines, teeth 10–13 are small, obscure or abdomen. They have a large plate-like absent. carapace dorsally, beneath which are five Perepods: Walking legs hairy, light pairs of thoracic appendages (see chelipeds colored and with darkly pigmented dactyls. and pereopods) and three pairs of Chelipeds: Dark nearly to tips (Fig. maxillipeds (see mouthparts). The abdomen 4), carpus (wrist) tuberculate above, short and associated appendages are reduced and spine at inner angle with tooth below. Hand folded ventrally (Decapoda, Kuris et al. 2007). (propodus) thick and high, with two rows of Cephalothorax: tubercules above and five granulate lines on Eyes: Eye stocks short. outer surface (Fig. 4). Chelae rougher in Antennae: Antennules folded females than in males (Rathbun 1930). lengthwise (Fig. 3) bear short, hairy flagella. Hiebert, T.C. and A. Burgess. 2015. Cancer oregonensis. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12698 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] Abdomen (Pleon): Abdomen narrow in and five subequal frontal teeth (Kuris et al. male, broad in female (e.g. see Cancer 2007). The carapace of C. magister is widest magister, Fig. 3). at the tenth tooth, is more subtly pigmented Telson & Uropods: and does not have black tipped dactyls seen Sexual Dimorphism: Male and female in C. productus (Wicksten 2011). The two brachyuran crabs are easily differentiable. species are often collected together in crab The most conspicuous feature, the abdomen, pots. Cancer antennarius, like C. productus, is narrow and triangular in males while it is is dark red with spots ventrally and with black wide and flap-like in females. Additionally, tipped chelae. However, the carapace width males have one large chelae and two pleopod in C. antennarius is widest at the eighth tooth pairs specialized for copulation, however, the and there are a total of 11 antero-lateral teeth third and fourth pleopods are absent. (Schmitt 1921; Kuris et al. 2007; Wicksten Females, on the other hand, have all four 2011). pleopod pairs, each with long setae for egg The remaining four species tend to be attachment (Brachyura, Kuris et al. 2007). smaller and have nine antero-lateral teeth Female C. oregonensis often have a more (sometimes ten in older specimens, Wicksten uneven and lumpy textured carapace 2011). Cancer branneri is a small species (35 (sometimes with high, flattened elevations) mm) that is rare intertidally and recognizable and rougher chelae than males. by cheliped dactyls that are long, straight, black and spiny. Cancer gracilis (27 mm) has Possible Misidentifications white-tipped cheliped dactyls and C. jordani According to some authors, the genus Cancer (25 mm) has a hairy carapace and sharp comprises 23 species (Harrison and Crespi curving teeth. Cancer anthonyi, the yellow 1999 but see Schweitzer and Feldmann rock crab, is larger than the previous three at 2000). This genus is differentiated from other 52 mm and has black-tipped cheliped dactyls brachyuran genera by the broadly oval (Kuris et al. 2007; Wicksten 2011). carapace, presence of five frontal teeth and Populations of C. productus, C. anthonyi antennules that fold back over carapace. (southern California) and C. magister support Characters unique to Cancer oregonensis commercial fisheries (Kuris et al. 2007). include 12–13 antero-lateral teeth, carapace widest at 7–8 tooth, red color, black-tipped Ecological Information cheliped dactyls and small size (Kuris et al. Range: Type locality is Puget Sound, 2007). Cancer oregonensis is the only Washington. Known range includes Aleutian member of the genus with a distinctly elliptical Islands in Alaska to Lower California (Schmitt carapace, without distinct angle at the 1921; Ricketts and Calvin 1971; Wicksten posterior-anterior margin. It is smaller than 2011). Rare south of Oregon (Kuris et al. most of the other adult Cancer species, but 2007). can be confused with their juveniles, which Local Distribution: Coos Bay distribution at occur only seasonally, not all year, as will C. Fossil and Pigeon points. oregonensis. The key characteristic is the Habitat: Rocky intertidal and subtidal areas rounded, not angled carapace shape. Cancer of quiet bays, tidepools and well embedded oregonensis occupies a very particular niche: rock and mud. Likes closely fitting shells, in the under-rock habitat, often found nestled crannies. in a well-fitting discarded mollusk or barnacle Salinity: Found at lower (saltier) end of bays. shell (Garth and Abbott 1980; Kozloff 1993). Temperature: A cold and temperate water There are eight Cancer species known dweller (by geographical range). locally (Kuris et al. 2007) and three of those Tidal Level: Low intertidal to 435 m are larger than C. oregonensis in their adult (Rathbun 1930; Wicksten 2011). form including, C. magister (adults at least 30 Associates: In the under-rock low intertidal mm in width), C. productus (adults over 20 of bays associates include burrowing clams mm in width) and C. antennarius (adults (Pholadidae), terebellid polychaete Thelepus typically 100 mm in width). Cancer productus and its associate Halosydna. Subtidally, the and C. magister have 10 antero-lateral teeth large barnacle Balanus nubilis, whose Hiebert, T.C. and A. Burgess. 2015. Cancer oregonensis. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. discarded shell is often home to C. Longevity: oregonensis. A parasitic barnacle Growth Rate: Growth occurs in conjunction (Rhizocephalan) becomes prevalent in with molting. In pre-molting periods the Alaskan animals (Ricketts and Calvin 1971). epidermis separates from the old cuticle and Abundance: Occurs commonly within its a dramatic increase in epidermal cell growth habitat. occurs. Post-molt individuals will have soft shells until a thin membranous layer is Life-History Information deposited and the cuticle gradually Reproduction: All decapod crustacean hardens. During a molt decapods have the females attach recently laid gelatinous egg ability to regenerate limbs that were masses to their pleopods. The outer embryo previously autotomized (Kuris et al. 2007). membrane thickens and a strand develops Food: Predator and scavenger on other that attaches each embryo to pleopod