Overview

Comprehensive Description

Biology/Natural History: These crabs are often found in pairs, and may be in such a tightly secluded space that they appear to be trapped. They feed by straining plankton from the water with their third maxillipeds. Captive individuals also catch worms and small crustaceans with their small claw and crush mussels with the large claw. Predators include black oystercatchers.
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Source: Invertebrates of the Salish Sea

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As a Lithodid crab, this species has no uropods and the abdomen is folded against the underside of the thorax. Its 5th walking legs are reduced. Oedignathus inermis has a thick, soft abdomen which is not tightly held under the thorax (photo). The first (basal) segment of the abdomen has calcified plates, as do the two terminal ones. Oedignathus inermis has chelipeds very unequal in size (the right cheliped is largest) and the dactyl is shorter than the "palm" of the propodus. The rostrum is sharp but has no spines (photo). The legs are rounded (not heavily flattened). The chelipeds have large granular tubercles but no spines on the upper surface. The large cheliped has violet to gray or blue tubercles and a smooth tan to white tip to the claw with a spoonlike hollow where the propodus and dactyl contact one another. The shall cheliped has small, sharp granules and setae. The walking legs have sharp granules, setae, and dark brown and white spots (photo). The anterior margins of legs 2-4 have some setae, tubercles, and small spines but no large spines. Note, however, that there are large spines on the anterior margins of leg 1 (the chelipeds). Carapace to 3 cm long and 2.5 cm wide in males, 2 cm wide in females; wider posteriorly than anteriorly, brown with scales on the dorsal surface. It has white-centered orange granules and dark brown spots, but these colors may be masked by mud. May have white on the sternum. There are few if any setae on the body.
  • Hart, Josephine F.L., 1982. ;Crabs and their relatives of British Columbia. ; British Columbia ProvincialMuseum Handbook 40. ; Paperback. ; 267 pages. ; This smallpaperback contains keys and individual descriptions and drawings of 95species of true crabs, hermit crabs, other anomurans, mud and ghost shrimp(but not shrimp or prawns) found off British Columbia. ; An introductiongives an extensive discussion of the general biology and anatomy of crabsand other similar crustaceans, including topics such as sexual dimorphism,larvae, and parasites. ; A variety of drawings and tables are included. ;The general characteristics of each of the families included in the bookare discussed. ; Keys to the families of each section (Thalassinidea,Anomura, Brachyrua) are included but one needs to know beforehand whichsection the animal is in. ; Keys are also included for the membersof each family. ; A useful key for the serious student wanting to identifycrabs.   http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Annotated_Bibliography.html#Hart+1982 External link.
  • Jensen, Gregory C., 1995. ;Pacific Coast Crabs and Shrimps. ; Sea Challengers, Monterey, CA. ;87 pp. ; ISBN 0-930118-20-0. ; This paperback contains excellentpictures and brief descriptions of many crabs and shrimp from along thePacific coast. ; Sections are arranged by animal group. ; Includesa short glossary.   http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Annotated_Bibliography.html#Jensen+1995 External link.
  • Wicksten,Mary K., 2009. ; Decapod Crustacea of the Californian and OregonianZoogeographic Provinces. ; UC San Diego Scripps Institution of OceanographyLibrary, Scripps Institution of Oceanography. ; http://escholarship.org/uc/item/7sk92dz ;418 pages. ; Published online only. ; This excellent key coversdecapods (crustaceans such as crabs, shrimp, spiny lobsters, hermit crabs,and crayfish) from shallow and deep water from Puget Sound south to thePacific coast of Baja California. ; Includes many subkeys, drawings,and photos. ; No glossary, table of contents, or index. ; Thisis the place to go for the most up-to-date key for decapods. ; MaryWicksten plans to publish an updated version of this key soon.   http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Annotated_Bibliography.html#Wicksten+2009 External link.
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Source: Invertebrates of the Salish Sea

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Distribution

Geographical Range: Amchitka Island, AK to Monterey, CA; eastern Russia, Japan, Korea. Mostly on the open coast. Rarely seen in the San Juan islands and is said to not to occur in Puget Sound; rare in California.

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Source: Invertebrates of the Salish Sea

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Physical Description

Type Information

Syntype for Oedignathus inermis (Stimpson, 1860)
Catalog Number: USNM 18525
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: male;
Preparation: Dry
Locality: Alaska, United States, North Pacific Ocean
  • Syntype:
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© Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology

Source: National Museum of Natural History Collections

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Look Alikes

How to Distinguish from Similar Species: Of the Lithodid crabs with soft abdomens, Placetron wosnessenskii has a much thinner abdomen and has scales on the carapace and legs. Acantholithodes hispidus has large spines on the rostrum. Hapalogaster mertensii and H. grebnitzkii have strongly flattened cephalothorax and legs and have spines on the upper surface of their chelipeds.
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Source: Invertebrates of the Salish Sea

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Ecology

Habitat

Depth range based on 7 specimens in 1 taxon.
Water temperature and chemistry ranges based on 7 samples.

Environmental ranges
  Depth range (m): 0 - 40
  Temperature range (°C): 2.696 - 10.151
  Nitrate (umol/L): 6.725 - 14.086
  Salinity (PPS): 31.692 - 32.340
  Oxygen (ml/l): 6.534 - 7.044
  Phosphate (umol/l): 0.943 - 1.620
  Silicate (umol/l): 14.539 - 31.138

Graphical representation

Depth range (m): 0 - 40

Temperature range (°C): 2.696 - 10.151

Nitrate (umol/L): 6.725 - 14.086

Salinity (PPS): 31.692 - 32.340

Oxygen (ml/l): 6.534 - 7.044

Phosphate (umol/l): 0.943 - 1.620

Silicate (umol/l): 14.539 - 31.138
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth Range: Middle intertidal to 15 m

Habitat: Under encrusting coralline algae, under Mytilus californianus mussels or Anthopleura xanthogrammica anemones, in crevices, and in other protected areas

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Oedignathus inermis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Source: Barcode of Life Data Systems (BOLD)

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Wikipedia

Oedignathus

Oedignathus inermis is a species of king crab found off the Pacific coasts of the United States and Canada, from California[3] to Alaska,[4] and disjunctly around the coasts of Japan.[5] It is the only species in the genus Oedignathus, and is sometimes called the granular claw crab,[2] paxillose crab[6] or tuberculate nestling lithode crab.[7]

Characteristics

Oedignathus is distinguished from other king crabs in the subfamily Hapalogastrinae by the presence of numerous tubercles on the only slightly flattened chelipeds and legs, and by the paucity of spines, setae; other genera have flattened chelipeds covered in setae, and legs with several large spines.[8]

Ecology

O. inermis lives in pairs under the purplish coralline algae which encrust the rocks around the low tide mark,[3] and may be found at depths of 0–45 metres (0–148 ft).[5] When in the littoral zone, O. inermis is associated with mussel beds, but it spends more time in the sublittoral zone.[9] Larvae are released in January and February, at a similar time to other hermit crabs, perhaps to coincide with seasonal blooms of plankton for the larvae to feed on.[10]

O. inermis is preyed upon by birds such as the American black oystercatcher.[11]

References

  1. ^ "Oedignathus". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=97928.
  2. ^ a b "Oedignathus inermis". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=97929.
  3. ^ a b G. E. MacGintie (1937). "Notes on the natural history of several marine crustacea". American Midland Naturalist (The University of Notre Dame) 18 (6): 1031–1037. doi:10.2307/2420601. JSTOR 2420601.
  4. ^ "Oedignathus inermis (Stimpson, 1860)". Global Biodiversity Information Facility. http://newportal.gbif.org/species/13794083. Retrieved 2007-08-16.
  5. ^ a b V. V. Petryashev (2005). "Biogeographical division of the North Pacific sublittoral and upper bathyal zones by the fauna of Mysidacea and Anomura (Crustacea)". Russian Journal of Marine Biology 31 (Supplement 1): S9–S26. doi:10.1007/s11179-006-0011-7.
  6. ^ Bradley G. Stevens. "A Checklist of Alaskan Crabs". National Oceanic and Atmospheric Administration. http://www.afsc.noaa.gov/kodiak/shellfish/crabEBS/crablist.pdf.
  7. ^ "British Columbia Estuary Mapping System". Integrated Land Management Bureau, Province of British Columbia. March 1999. http://ilmbwww.gov.bc.ca/risc/pubs/coastal/estuary/estuary-28.htm.
  8. ^ Dave Cowles (2006). "Key to Family Lithodidae". Walla Walla University. http://rosario.wwc.edu/inverts/Arthropoda/Crustacea/Malacostraca/Eumalacostraca/Eucarida/Decapoda/Anomura/Family_Lithodidae/Lithodidae_Key.html.
  9. ^ Stephen H. Morrell, Harriet R. Huber, T. James Lewis & David G. Ainley (1979). "Feeding ecology of black oystercatchers on South Farallon Island, California". Studies in Avian Biology 2: 185–186.
  10. ^ S. Wada, H. Kitaoka & S. Goshima (2000). "Reproduction of the hermit crab Pagurus lanuginosus and comparison of reproductive traits among sympatric species". Journal of Crustacean Biology 20 (3): 474–478. doi:10.1651/0278-0372(2000)020[0474:ROTHCP]2.0.CO;2.
  11. ^ J. Timothy Wootton (1997). "Estimates and tests of per capita interaction strength: diet, abundance, and impact of intertidally foraging birds" (PDF). Ecological Monographs 67 (1): 45–64. doi:10.1890/0012-9615(1997)067[0045:EATOPC]2.0.CO;2. http://pondside.uchicago.edu/ecol-evol/faculty/Wootton/PDFs/97WoottonEM.pdf.
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