Hemigrapsus Oregonensis Class: Malacostraca Order: Decapoda Section: Brachyura a Hairy Shore Crab Family: Varunidae

Home , Grapsidae, Hemigrapsus oregonensis, Varunidae

Phylum: Arthropoda, Crustacea Hemigrapsus oregonensis Class: Malacostraca Order: Decapoda Section: Brachyura A hairy shore crab Family: Varunidae

Taxonomy: The brachyuran family and associated appendages are reduced and Grapsidae, the shore crabs, was a very large folded ventrally (Decapoda, Kuris et al. 2007). family with several subfamilies and little Cephalothorax: taxonomic scrutiny, until recently. Based on Eyes: Eyestalks and orbits molecular and morphological evidence, moderately sized (Rathbun 1918) and eyes at authors (von Sternberg and Cumberlidge antero-lateral angle (Fig. 2). 2000; Schubart et al. 2000; de Grave et al. Antennae: 2009; Schubart 2011) elevated all grapsid Mouthparts: The mouth of decapod subfamilies to family level, reducing the crustaceans comprises six pairs of number of species formally within the appendages including one pair of mandibles Grapsidae. Recent molecular evidence has (on either side of the mouth), two pairs of placed Hemigrapsus species within the maxillae and three pairs of maxillipeds. The Varunidae, but this is currently debated where maxillae and maxillipeds attach posterior to some authors still refer to them as members the mouth and extend to cover the mandibles of the Grapsidae sensu lato (Ng et al. 2008; (Ruppert et al. 2004). Wicksten 2012) and others have adopted the Carapace: Rectangular or square in new familial designation (e.g. Kuris et al. shape and wider than long with rounded 2007). Besides the higher taxonomic antero-lateral margins. Carapace surface is classifications, the known specific synonym smooth and bears three teeth (two lateral that for H. oregonensis is Pseudograpsus are posterior to postorbital) (Wicksten 2012) oregonensis (Wicksten 2012), which is not on antero-lateral margin, no transverse lines currently used. (Fig. 1). Frontal Area: Less than half the Description width of the carapace with two prominent Size: Carapace 34.7 mm in width and 28.4 frontal lobes and deep median sinus mm in length (Rathbun 1918; Wicksten 2012) (Wicksten 2012). Frontal margin without teeth (Fig. 1). The carapace of reproductive (Hemigrapsus, Kuris et al. 2007). individuals measures approximately 50 mm Teeth: Two lateral carapace teeth, (Puls 2001). with deep sinuses, below outer orbital tooth Color: Dull brownish green, gray to uniform (Fig. 2). light gray or muddy yellow with no red spots Pereopods: More or less hairy on chelipeds (compare H. nudus, Plate 21, (compare to H. nudus) (Fig. 1). Kozloff 1993; Kuris et al. 2007). Nearly white Chelipeds: Stout and equal or almost or yellow forms of both Hemigrapsus species equal in size. Dactyls hollowed in shallow have been reported (Ricketts and Calvin groove and male with mat of fine hair on 1971; Wicksten 2012). propodus. General Morphology: The body of decapod Abdomen (Pleon): Females with wide crustaceans can be divided into the abdomen and male H. oregonensis have cephalothorax (fused head and thorax) and narrow abdomens that exposes the sternum abdomen. They have a large plate-like at the base (see Sexual Dimorphism, Fig. 3). carapace dorsally, beneath which are five Telson & Uropods: pairs of thoracic appendages (see chelipeds Sexual Dimorphism: Male and female and pereopods) and three pairs of brachyuran crabs are easily differentiable. maxillipeds (see mouthparts). The abdomen The most conspicuous feature, the abdomen,

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12711 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] is narrow and triangular in males while it is cyaneus, is a pelagic species that is only wide and flap-like in females (Brachyura, found washed ashore on drift logs with Kuris et al. 2007). Male H. oregonensis have gooseneck barnacles (Kuris et al. 2007). a narrow abdomen that exposes the sternum Rhithropanopeus harrisii, an introduced (Fig. 3) and hairy chelipeds. Females have a xanthid (Panopeidae) mud crab, is sometimes wide abdomen and ho hairy patch on palm found with H. oregonensis. It has a slightly (only a few bristles). convergent sides, strong dorsal ridges on its carapace and three sharp carapace teeth. Possible Misidentifications Hemigrapsus species were formally members Ecological Information of the Grapsidae, a family characterized by Range: Type locality is Puget Sound, the carpus of the third maxilliped not Washington. Known range includes Alaska to articulating near the anterior merus angle and Baja California, Mexico (Wicksten 2012). by lateral mouth margins that are parallel or Local Distribution: Common in many convergent (Wicksten 2012). The genus Oregon bays including Yaquina, Siletz, Hemigrapsus may now be a member of the Tillamook, Netarts, Coos and Coquille family Varunidae (see Taxonomy) (Ricketts and Calvin 1971). characterized by chelae morphology, gaping Habitat: Quiet water, rocky habitats within third maxillipeds and setose walking legs (Ng estuaries, gravel shores but prefers muddy et al. 2008). Two Hemigrapsus species occur habitats (Ricketts and Calvin 1971) and salt locally, H. oregonensis and H. nudus. marshes. On muddy bottoms of estuaries Hemigrapsus nudus, the purple shore crab, is and on eelgrass and amongst Enteromorpha. larger than H. oregonensis, is “naked” (i.e. not Also in muddy spots on the open rocky coast. hairy) on its walking legs and has chelipeds The two Hemigrapsus species can co-occur, with conspicuous red spots. Hemigrapsus but one usually finds one or the other and H. nudus lives mostly on the rocky open coast, oregonensis prefers quieter water than does but is also found in salt marshes (Knudsen H. nudus (Kozloff 1993). 1964). Hemigrapsus oregonensis has been Salinity: Hemigrapsus oregonensis tolerates called a small, bleached edition of H. nudus salinity ranging from 17.5–31.6 (San (Ricketts and Calvin 1971). The following Francisco, California), likes freshwater seeps features are particularly useful in (Garth and Abbott 1980) and cannot tolerate differentiating the two Hemigrapsus species: much desiccation. 1) H. oregonensis has a marked frontal notch Temperature: Small animals most tolerant to where H. nudus has a shallow depression, 2) temperature extremes (Todd and Dehnel the lateral spines of H. oregonensis are sharp 1960). and distinctly separated from the side but H. Tidal Level: Found at very high and very low nudus spines are not, 3) The dactyls of tide levels, but usually lower intertidal than H. walking legs 1–3 are long in H. oregonensis nudus (Todd and Dehnel 1960). Individuals and short in H. nudus and 4) the dactyl of the can be found at higher tidal reaches of the fourth walking leg is round in H. oregonensis mudflats (Ricketts and Calvin 1971) and mid and flat in H. nudus (Kuris et al. 2007). The to low intertidal of bays as well as sublittorally final varunid crab that occurs locally is the (Kuris et al. 2007). introduced Chinese mitten crab, Eriocheir Associates: Hemigrapsus oregonensis has sinensis, but this species is very large and many associates. In gravel, isopods Idotea easily differentiable from either Hemigrapsus and Gnorimosphaeroma, and occasionally H. species. nudus (Kozloff 1993). Alga Ulva Pachygrapsus crassipes, a member of (sublittorally), and pickleweed, Salicornia (in the Grapsidae, is a dark green crab with marshes) (Kuris et al. 2007; Wicksten 2012). many transverse dark red striations on its legs The parasitic castrating isopod, Portunion and carapace (H. oregonensis is smooth), its conformis, is sometimes within the frontal margin is straight and it has one lateral perivisceral cavity of H. oregonensis (Garth tooth, not two (Symons 1964). The only other and Abbott 1980) with infection rates up to locally occurring grapsid crab, Planes 40% (Jaffe et al. 1987; Kuris et al. 2007).

Hiebert, T.C. 2015. Hemigrapsus 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. Hemigrapsus oregonensis, H. nudus and P. second and third segments (Puls 2001). The crassipes can all be host to the nemertean larvae of H. oregonensis are also a bit smaller egg predator, Carcinonemertes epialti, which and more slender than that of the closely can negatively impact brood mortality in these related H. nudus (Jaffe et al. 1987). The zoea species (Shields and Kuris 1988). These of Hemigrapsus species and P. crassipes can three species can also serve as intermediate be differentiated by body and eye size hosts for a variety of parasites including (Schlotterbeck 1976). Hemigrapsus trematode metacercariae, larval oregonensis megalopae are rectangular and trypanorhynch tapeworms, as well as can be recognized by a posterior telson Polymorphus acanthocephalan and nematode without setae (other than uropod setae) and a (Ascarophis) larvae (Kuris et al. 2007). carapace that is 1.4–1.7 mm in length and Abundance: In great numbers, benthically, 1.1–1.3 mm in width. The first in-star stage is in estuaries and usually common on gravelly reached after approximately 4–5 weeks (Puls substrates (Wicksten 2012). 2001). Juvenile: Very small animals have a marked Life-History Information frontal notch and sharp lateral spines and Reproduction: In Vancouver, Canada, long dactyls on walking legs (1–3) (Smith and females are ovigerous in March and hatch in Carlton 1975). Juveniles in both sexes have May, while in Puget Sound, Washington, they narrow abdomens. are ovigerous earlier (in Feb–April) and hatch Longevity: between May and July. Broods include 800– Growth Rate: Growth occurs in conjunction 11,000 embryos and 70% of females produce with molting. In pre-molting periods the a second brood that will hatch in September. epidermis separates from the old cuticle and Embryos change color as they mature from a dramatic increase in epidermal cell growth white to purple to brown before they hatch at occurs. Post-molt individuals will have soft which time they are approximately 300–400 shells until a thin membranous layer is µm in diameter (Jaffe et al. 1987). In the lab, deposited and the cuticle gradually hatching occurs after 44 days (10–12˚C, Jaffe hardens. During a molt decapods have the et al. 1987). The reproduction and life-cycle ability to regenerate limbs that were of C. epialti is dependent on and corresponds previously autonomized (Kuris et al. 2007). to that of its host species. However, this Food: Primarily an herbivore, scraping Ulva nemertean is not host specific (unlike or Enteromorpha off rocks, H. oregonensis Carcinonemertes errans on Cancer magister) uses tactile, visual and chemical sense to find and occurs amongst egg masses of other food (Knudsen 1964; Kozloff 1993). species including H. nudus, Pachygrapsus Predators: Birds (e.g. willet, Rathbun 1918). crassipes (Roe et al. 2007). Interestingly, it Behavior: A moderately active species that may be more common on H. oregonensis is a good digger and probably nocturnal than P. producta, for which it was described (Knudsen 1964; Garth and Abbott 1980; Kuris (Kuris 1993; Kuris et al. 2007). et al. 2007). Larva: Larval development in H. oregonensis proceeds via a series of zoea (five total) and megalopae stages, each marked by a molt. Bibliography The zoea are planktotrophic and have large compound eyes and four spines: one each 1. DE GRAVE, S., N. D. PENTCHEFF, dorsal and rostral and two lateral (see Fig. 32, S. T. AHYONG, T. CHAN, K. A. Puls 2001; Fig. 54.5, Martin 2014). The CRANDALL, P. C. DWORSCHAK, D. rostrum and dorsal spines are of equal length L. FELDER, R. M. FELDMANN, C. and the two lateral spines are shorter (Puls FRANSEN, L. Y. D. GOULDING, R. 2001). The first zoea has exospines on the LEMAITRE, M. E. Y. LOW, J. W. telson, is approximately 1.1 mm (measured MARTIN, P. K. L. NG, C. E. from tip of rostrum to tip of telson) and has SCHWEITZER, S. H. TAN, D. lateral knobs on the second segment only, TSHUDY, and R. WETZER. 2009. A where H. nudus has lateral knobs on the classification of living and fossil

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12711 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] genera of decapod crustaceans. Identification guide to larval marine Raffles Bulletin of Zoology:1-109. invertebrates of the Pacific Northwest. 2. GARTH, J. S., and D. P. ABBOTT. A. Shanks (ed.). Oregon State 1980. Brachyura: The true crabs, p. University Press, Corvallis, OR. 594-630. In: Intertidal invertebrates of 11. RATHBUN, M. J. 1918. The grapsoid California. R. H. Morris, D. P. Abbott, crabs of America. Bulletin of the and E. C. Haderlie (eds.). Stanford United States Natural Museum. University Press, Stanford, CA. 97:128-145. 3. KNUDSEN, J. W. 1964. Observations 12. RICKETTS, E. F., and J. CALVIN. of the reproductive cycles and ecology 1971. Between Pacific tides. Stanford of the common Brachyura and crablike University Press, Stanford, California. Anomura of Puget Sound, 13. ROE, P., J. L. NORENBURG, and S. Washington. Pacific Science. 18:3-33. MASLAKOVA. 2007. Nemertea, p. 4. KOZLOFF, E. N. 1993. Seashore life 221-233. In: Light and Smith manual: of the northern Pacific coast: an intertidal invertebrates from central illustrated Guide to northern California, California to Oregon. J. T. Carlton Oregon, Washington, and British (ed.). University of California Press, Columbia. University of Washington Berkeley, CA. Press, Seattle, WA. 14. RUPPERT, E. E., R. S. FOX, and R. 5. KURIS, A. M. 1993. Life cycles of D. BARNES. 2004. Invertebrate nemerteans that are symbiotic egg zoology: a functional evolutionary predators of decapod crustacea: approach. Thomson Brooks/Cole, adaptations to host life histories. Belmont, CA. Hydrobiologia. 266:1-14. 15. SCHLOTTERBECK, R. E. 1976. 6. KURIS, A. M., P. S. SADEGHIAN, J. Larval development of the lined shore T. CARLTON, and E. CAMPOS. 2007. crab, Pachygrapsus crassipes Decapoda, p. 632-656. In: The Light Randall, 1840. (Decapod: Brachyura: and Smith manual: intertidal Grapsidae) reared in the laboratory. invertebrates from central California to Crustaceana. 30:184-200. Oregon. J. T. Carlton (ed.). University 16. SCHUBART, C. D. 2011. of California Press, Berkeley, CA. Reconstruction of phylogenetic 7. MARTIN, J. W. 2014. Brachyura, p. relationships within Grapsidae 295-310. In: Atlas of crustacean (Crustacea: Brachyura) and larvae. J. W. Martin, J. Olesen, and J. comparison of trans-isthmian versus T. Høeg (eds.). Johns Hopkins amphi-atlantic gene flow based on University Press, Baltimore, MD. mtDNA. Zoologischer Anzeiger. 8. NG, P. K. L., D. GUINOT, and P. J. F. 250:472-478. DAVIE. 2008. Systema brachyurorum: 17. SCHUBART, C. D., J. A. CUESTA, R. Part I. Annotated checklist of the DIESEL, and D. L. FELDER. 2000. extant Brachyuran crabs of the world. Molecular phylogeny, taxonomy, and Raffles Bulletin of Zoology evolution of non-marine lineages Supplement. 17:1-286. within the American grapsoid crabs 9. NYBLADE, C. F. 1987. Phylum or (Crustacea: Brachyura). Molecular Subphylum Crustacea, Class Phylogenetics and Evolution. 15:179- Malacostraca, Order Decapoda, 190. Anomura, p. 441-450. In: 18. SHIELDS, J. D., and A. M. KURIS. Reproduction and development of 1988. Temporal variation in marine invertebrates of the northern abundance of the egg predator Pacific coast. M. F. Strathmann (ed.). Carcinonemertes epialti (Nemertea) University of Washington Press, and its effect on egg mortality of its Seattle, WA. host, the shore crab, Hemigrapsus 10. PULS, A. L. 2001. Arthropoda: oregonensis. Hydrobiologia. 156:31- Decapoda, p. 179-250. In: 38.