Cryptolithodes typicus Brandt, 1849

Common name(s): Butterfly crab
Synonyms:
Phylum Arthropoda
 Subphylum Crustacea
  Class Malacostraca
   Subclass Eumalacostraca
    Superorder Eucarida
     Order Decapoda
      Suborder Pleocyemata
       Infraorder Anomura
        Superfamily Paguroidea
         Family Lithodidae
Cryptolithodes typicus from Sares Head (subtidal).
(Photo by: Dave Cowles, July 1997)
Description:  This lithodid crab has a carapace that spreads hugely, covering not only the thoracic segments but extending so far out that when the animal is inactive not even the tips of the legs can be seen from above.  The rostrum is widest at the base and narrower at the tip (picture).  The propodus of its chelipeds are covered with rough tubercles (picture), and its abdominal plates have a raised ridge around the margin (picture). Carapace color is quite variable, from dark gray-blue as here to bright orange (picture), white (especially in small individuals), or red (especially in males).  The central part of the carapace is often a different color than the "wings".  Carapace width to 8 cm.

How to Distinguish from Similar Species: Cryptolothodes sitchensis has a similar carapace but its rostrum is widest at the tip and its chelae are smooth.

Geographical Range: Amchitka Island, Alaska to Santa Rosa Island, CA.  Less common in the southern parts of the range.

Depth Range: Low intertidal to 45 m

Habitat: Rocky banks, shell rubble near rocky cliffs.  Open coast or inland waters, especially in high current areas.

Biology/Natural History: Feeds on bryozoans, coralline algae, and other attached species.  Usually lives deeper than does C. sitchensis.


 
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References:

Dichotomous Keys:
  Coffin, 1952
  Flora and Fairbanks, 1966
  Hart, 1982
  Kozloff 1987, 1996
  Wicksten, 2009
 

General References:
Jensen, 1995
O'Clair and O'Clair, 1998

Scientific Articles:
 


General Notes and Observations:  Locations, abundances, unusual behaviors:


This species has a rostrum widest at the base, which helps distinguish this species from Cryptolithodes sitchensis.
Note eyestalks projecting at the base of the rostrum.  Photo by Dave Cowles, 2001



Here is the whole individual photographed above.  Photo by Dave Cowles, July 2001


Cryptolithodes typicus can stretch its claws out from under the carapace.  Photo by Dave Cowles, 1997


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Underside of Cryptolithodes typicus.  Note ridges lining the edges of abdominal segments, and the roughness of the propodus on the chela.  Photo by Dave Cowles, 1997
Note also that the chela (claw) is quite blunt.


Authors and Editors of Page:
Dave Cowles (2005):  Created original page