Pagurus Hirsutiusculus Class: Malacostraca Order: Decapoda Hairy Hermit Crab Section: Anomura, Paguroidea Tribe: Paguridea
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Phylum: Arthropoda, Crustacea Pagurus hirsutiusculus Class: Malacostraca Order: Decapoda Hairy hermit crab Section: Anomura, Paguroidea Tribe: Paguridea Taxonomy: The taxonomy in the Paguroidea is elongated, soft and coiled in Paguridae is complicated, especially among the genera (Kuris et al. 2007) (Fig. 1). Eupagurus, Bernhardus and Pagurus (described in McLaughlin et al. 2010). The Cephalothorax: International Commission of Zoological Eyes: Eyestalks short, stout and with Nomenclature (Opinion 472) placed the pointed ocular scales (Wicksten 2011). generic names Eupagurus and Bernhardus in Antennae: Antennal acicle usually the official index of invalid and rejected exceeds eyestalk in length. Chemoreceptors names, leaving the genera Pagurus on antennule hairs (Barnard et al. 1980). (Paguridae) and Dardanus (Diognidae) as Mouthparts: The mouth of decapod valid (Hemming 1958). Thus, previous crustaceans comprises six pairs of synonyms for Pagurus hirsutiusculus include appendages including one pair of mandibles Bernhardus hirsutiusculus (McLaughlin et al. (on either side of the mouth), two pairs of 2010; Wicksten 2011). maxillae and three pairs of maxillipeds. The maxillae and maxillipeds attach posterior to Description the mouth and extend to cover the mandibles Size: Carapace length 19–32 mm (Barnard (Ruppert et al. 2004). et al. 1980; Kozloff 1993). Puget Sound to 50 Carapace: Shield (hard, anterior mm (Ricketts and Calvin 1971) and body portion) wider than long (McLaughlin 1972) often extends past the margin of the shell and (Fig. 1). cannot be retracted (Kuris et al. 2007). Rostrum: Triangular (Fig. 1), acute Color: Body color tan to black or green. and not much longer than lateral projections Antennae dark green with white stripes. of carapace (Wicksten 2011). Propodus of walking legs hairy and tipped Teeth: Sharp medial frontal tooth with white or pale blue and dactyls with (Barnard et al. 1980). vertical red stripes and blue spots at base. Pereopods: Two pairs of hairy Tips of chela tan or orange and walking legs walking legs with dactyls about as long as have white band on propodus and sometimes propodi, which are banded with white. a blue dot. Dactyls whitish and striped with Dactyls slender and about as long as propodi blue and red, antennal flagellum banded with (Wicksten 2011). Two pairs of small posterior translucent and brown (Wicksten 2011) or legs are adapted for holding shell. greenish with yellow spots (Barnard et al. Chelipeds: Left cheliped with small 1980). Most recognizable patterns are white hand and granular surface, slightly hairy and spots on antennae and white bands around wider than deep (Fig. 2). Right cheliped with base of second and third legs (see Plate 20 large hand, rounded, twice as wide as small and Fig 117, Kozloff 1993) (Fig. 1). hand, granular, slightly hairy and with one General Morphology: The body of decapod large tubercule on ventral surface (Fig. 2). crustaceans can be divided into the Cheliped stout and shorter than walking legs, cephalothorax (fused head and thorax) and is elongated and fingers gaping in male. abdomen. They have a large plate-like Merus and carpus with setae, granules, carapace dorsally, beneath which are five spines and ridges. pairs of thoracic appendages (see chelipeds Abdomen (Pleon): Abdomen asymmetrical, and pereopods) and three pairs of elongate, twisted, soft and not externally maxillipeds (see mouthparts). The abdomen segmented (Fig. 1). Bears small, unpaired pleopods. 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. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12728 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] Telson & Uropods: Telson and uropods North America: Diogenidae, Parapaguridae small. Telson with slightly asymmetrical lobes and Paguridae (Wicksten 2011). and a shallow clefts laterally. Posterior Parapaguridae species occur on the margin with notch and spines. Uropods also continental shelf. Diogenidae species, called asymmetrical (Wicksten 2011). “left-handed” (left cheliped is equal to or Sexual Dimorphism: Males usually larger larger than right) hermit crabs, are generally than females (MacGinitie and MacGinitie subtidal and often inhabit the shells of moon 1949). snails. The family Diogenidae includes three Shell: Usually inhabits Nassarius fossatus, local species, Isocheles pilosus, Paguristes Nucella lamellosa (e.g. this specimen) (in ulreyi, and P. bakeri). The Paguridae, or bays, Schmitt 1921), Nucella emarginata or “right-handed” (right cheliped is larger than Littorina sp. (Kozloff 1993). Individuals often left) hermit crabs, on the other hand, are a inhabit shells of Nucella spp. except in San speciose family locally, with 10 species, Francisco Bay, where it uses shells of inhabiting the intertidal zone to the continental gastropod species introduced from the shelf. Nine of the 10 local pagurid species Atlantic. Moves to larger shells with increased belong to the genus Pagurus (Kuris et al. growth. Innate selection of shell is dependent 2007). The hermit crabs of the genus on size, weight and shell volume (Reese Pagurus are hard to tell apart. However, 1962) and even the potential camouflaging many local species can be easily properties of the shell (Partridge 1980). differentiated by their bright red or orange Individuals carefully examine and select antennae and, likewise, many are similar to P. appropriate shells with their setaceous minor hirsutiuseulus in their lack of red antennae. chela. These setae have sensory structures Pagurus hirsutiusculus can be and chemoreceptors that contribute to shell distinguished from other Pagurus species in selection (Mesce 1993). Furthermore, shell that the carapace shield is conspicuously type (i.e. snail species) may be species- wider than long and has antennae that are specific and vary throughout ontogeny banded green and white. Furthermore, (Straughan and Gosselin 2014). Thus, individuals are often not able to fully retract available shells may be a limiting resource for into their shells. They are found inhabiting hermit crabs (Vance 1972; Worcester and the shells of Nucella spp. and may have Gaines 1997), but this may only be the case Crepidula spp. living on the inside or outside for a specific, preferred, shell type (i.e. of their shell. This species co-occurs with P. species). samuelis, but is the more common species in protected areas and bays. Possible Misidentifications Pagurus beringanus is also a low Hermit crabs (superfamilies, Coenobitoidea intertidal species, found at depths up to 364 and Paguroidea) are easily recognizable by m. This species has translucent antennae their unique morphology and the gastropod with a conspicuous lateral red mark and shells they inhabit (although they also inhabit usually inhabits shells of Nucella lamellosa, tubes, twigs or even bones). They use their Ceratostoma foliata and Fusitriton last preened pears to grip the shell and their oregonensis. It is found on rocky substrates soft abdomen with reduced pleopods and as well as sublittorally and has a whitish body, small telson and uropods. Their carapace is red banded walking legs, and has inverted V- usually rather thin, their eyes stalked and shaped tubercules on its hands (Wicksten have pigmented corneae. They have active 2011; Kuris et al. 2007). antennae, equipped with sensory setae. Pagurus quaylei is a subtidal species (to Their third maxillipeds are leg-like and bear 97 m) with antennae irregularly banded and setae and they have chelae that can be large dark brown, reddish brown eyestalks and enough to block their external shell aperture corneae with two bands. A common species or sexually dimorphic. amongst sand and polychaete tubes. Pagurus samuelis, P. hemphilli, P. Three hermit-crab families are currently granosimanus, P. armatus, and P. caurinus recognized and occur on the west coast of all have red or orange antennae, where P. 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. hirsutiuseulus does not. P. samuelis is a high Local Distribution: Coos Bay sites include intertidal species that is common and South Slough, near the channel at Collver abundant on the open coast, with red Point and the mudflat of Metcalf Preserve. antennae and carapace with white stripes. It Habitat: Protected areas with silt or in bays inhabits shells of Tegula spp and may have or harbors (Kozloff 1993; Wicksten 2011). Crepidula spp. living on top of or inside the Tidepools, under rocks (with coarse gravel), shell (Wicksten 2011). This species co- under seaweed (Kozloff 1993). South occurs with P. hirsutiusculus and is dominant Slough specimens occur within Zostera bed in to them in terms of shell competition and mudflats. Individuals appear to prefer algal exchange (Kuris et al. 2007). Pagurus cover (Orians and King 1964) and sandy hemphilli is a low intertidal and mostly subtidal tidepools (Reese 1962). Also present on the species (to 50 m) with red flagellum of rocky coast, in tide pools, bays and with antennae and corneae