Pagurus Hirsutiusculus Class: Multicrustacea, Malacostraca, Eumalacostraca
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Phylum: Arthropoda, Crustacea Pagurus hirsutiusculus Class: Multicrustacea, Malacostraca, Eumalacostraca Order: Eucarida, Decapoda, Pleocyemata, Anomura Hairy hermit crab Family: Paguroidea, Paguridae Taxonomy: The taxonomy in the Pagu- men. They have a large plate-like carapace roidea is complicated, especially among the dorsally, beneath which are five pairs of tho- genera Eupagurus, Bernhardus and Pagu- racic appendages (see chelipeds and pereo- rus (described in McLaughlin et al. 2010). pods) and three pairs of maxillipeds (see The International Commission of Zoological mouthparts). The abdomen is elongated, Nomenclature (Opinion 472) placed the ge- soft and coiled in Paguridae (Kuris et al. neric names Eupagurus and Bernhardus in 2007) (Fig. 1). the official index of invalid and rejected Cephalothorax: names, leaving the genera Pagurus Eyes: Eyestalks short, stout and with (Paguridae) and Dardanus (Diognidae) as pointed ocular scales (Wicksten 2011). valid (Hemming 1958). Thus, previous syn- Antenna: Antennal acicle usually ex- onyms for Pagurus hirsutiusculus include ceeds eyestalk in length. Chemoreceptors on Bernhardus hirsutiusculus (McLaughlin et al. antennule hairs (Barnard et al. 1980). 2010; Wicksten 2011). Mouthparts: The mouth of decapod crustaceans comprises six pairs of appendag- Description es including one pair of mandibles (on either Size: Carapace length 19–32 mm (Barnard side of the mouth), two pairs of maxillae and et al. 1980; Kozloff 1993). Puget Sound to three pairs of maxillipeds. The maxillae and 50 mm (Ricketts and Calvin 1971) and body maxillipeds attach posterior to the mouth and often extends past the margin of the shell extend to cover the mandibles (Ruppert et al. and cannot be retracted (Kuris et al. 2007). 2004). Color: Body color tan to black or green. An- Carapace: Shield (hard, anterior por- tennae dark green with white stripes. Propo- tion) wider than long (McLaughlin 1972) (Fig. dus of walking legs hairy and tipped with 1). white or pale blue and dactyls with vertical Rostrum: Triangular (Fig. 1), acute red stripes and blue spots at base. Tips of and not much longer than lateral projections chela tan or orange and walking legs have of carapace (Wicksten 2011). white band on propodus and sometimes a Teeth: Sharp medial frontal tooth blue dot. Dactyls whitish and striped with (Barnard et al. 1980). blue and red, antennal flagellum banded Pereopods: Two pairs of hairy walking with translucent and brown (Wicksten 2011) legs with dactyls about as long as propodi, or greenish with yellow spots (Barnard et al. which are banded with white. Dactyls slender 1980). Most recognizable patterns are white and about as long as propodi (Wicksten spots on antennae and white bands around 2011). Two pairs of small posterior legs are base of second and third legs (see Plate 20 adapted for holding shell. and Fig 117, Kozloff 1993) (Fig. 1). Chelipeds: Left cheliped with small General Morphology: The body of decapod hand and granular surface, slightly hairy and crustaceans can be divided into the cepha- wider than deep (Fig. 2). Right cheliped with lothorax (fused head and thorax) and abdo- A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Pagurus hirsutiusculus. 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. large hand, rounded, twice as wide as small Possible Misidentifications hand, granular, slightly hairy and with one Hermit crabs (superfamilies, Coenobi- large tubercule on ventral surface (Fig. 2). toidea and Paguroidea) are easily recogniza- Cheliped stout and shorter than walking ble by their unique morphology and the gas- legs, is elongated and fingers gaping in tropod shells they inhabit (although they also male. Merus and carpus with setae, gra- inhabit tubes, twigs or even bones). They use nules, spines and ridges. their last preened pears to grip the shell and Abdomen (Pleon): Abdomen asymmetrical, their soft abdomen with reduced pleopods elongate, twisted, soft and not externally and small telson and uropods. Their carapace segmented (Fig. 1). Bears small, unpaired is usually rather thin, their eyes stalked and pleopods. have pigmented corneae. They have active Telson & Uropods: Telson and uropods antennae, equipped with sensory setae. small. Telson with slightly asymmetrical Their third maxillipeds are leg-like and bear lobes and a shallow clefts laterally. Posteri- setae and they have chelae that can be large or margin with notch and spines. Uropods enough to block their external shell aperture also asymmetrical (Wicksten 2011). or sexually dimorphic. Sexual Dimorphism: Males usually larger Three hermit-crab families are currently than females (MacGinitie and MacGinitie recognized and occur on the west coast of 1949). North America: Diogenidae, Parapaguridae Shell: Usually inhabits Nassarius fossatus, and Paguridae (Wicksten 2011). Parapaguri- Nucella lamellosa (e.g. this specimen) (in dae species occur on the continental shelf. bays, Schmitt 1921), Nucella emarginata or Diogenidae species, called “left-handed” (left Littorina sp. (Kozloff 1993). Individuals often cheliped is equal to or larger than right) hermit inhabit shells of Nucella spp. except in San crabs, are generally subtidal and often inhabit Francisco Bay, where it uses shells of the shells of moon snails. The family Diogeni- gastropod species introduced from the dae includes three local species, Isocheles Atlantic. Moves to larger shells with pilosus, Paguristes ulreyi, and P. bakeri). The increased growth. Innate selection of shell Paguridae, or “right-handed” (right cheliped is is dependent on size, weight and shell larger than left) hermit crabs, on the other volume (Reese 1962) and even the potential hand, are a speciose family locally, with 10 camouflaging properties of the shell species, inhabiting the intertidal zone to the (Partridge 1980). Individuals carefully continental shelf. Nine of the 10 local pagurid examine and select appropriate shells with species belong to the genus Pagurus (Kuris et their setaceous minor chela. These setae al. 2007). The hermit crabs of the genus Pa- have sensory structures and gurus are hard to tell apart. However, many chemoreceptors that contribute to shell local species can be easily differentiated by selection (Mesce 1993). Furthermore, shell their bright red or orange antennae and, type (i.e. snail species) may be species- likewise, many are similar to P. hirsutiuseulus specific and vary throughout ontogeny in their lack of red antennae. (Straughan and Gosselin 2014). Thus, Pagurus hirsutiusculus can be distin- available shells may be a limiting resource guished from other Pagurus species in that for hermit crabs (Vance 1972; Worcester the carapace shield is conspicuously wider and Gaines 1997), but this may only be the than long and has antennae that are banded case for a specific, preferred, shell type (i.e. green and white. Furthermore, individuals are species). often not able to fully retract into their shells. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] They are found inhabiting the shells of Nu- local hermit crab species in the mid-littoral cella spp. and may have Crepidula spp. li- zone and within tide pools. This species has ving on the inside or outside of their shell. bright red antennae and commonly inhabits This species co-occurs with P. samuelis, but the shells of Tegula spp. Pagurus armatus is is the more common species in protected a low intertidal species, found at depths up to areas and bays. 146 m, and usually inhabits the shells of Pagurus beringanus is also a low in- Polinices spp., and are often covered with the tertidal species, found at depths up to 364 pink hydroid Hydractinia sp. Pagurus m. This species has translucent antennae caurinus is a subtidal species, to 126 m, and with a conspicuous lateral red mark and while it has a northern distribution it is rare at usually inhabits shells of Nucella lamellosa, that extent of its range. Pagurus ochetensis Ceratostoma foliata and Fusitriton is a low intertidal and subtidal species which oregonensis. It is found on rocky substrates often inhabits moon snail shells (Kuris et al. as well as sublittorally and has a whitish 2007). Their chelipeds have a red stripe, and body, red banded walking legs, and has their corneae are yellowish green. inverted V-shaped tubercules on its hands Ecological Information (Wicksten 2011; Kuris et al. 2007). Range: Type locality is Puget Sound, Wash- Pagurus quaylei is a subtidal species ington. Known range includes the Pribilof Is- (to 97 m) with antennae irregularly banded lands and Bering Strait to northern Japan and dark brown, reddish brown eyestalks (Barnard et al. 1980). Pacific Northwest to and corneae with two bands. A common Monterey, California (McLaughlin 1972). species amongst sand and polychaete Northern and southern populations used to be tubes. split into two subspecies: P. hirsutiusculus hir- Pagurus samuelis, P. hemphilli, P. sutiusculus