Pugettia gracilis Dana, 1851

Common name(s): Graceful kelp crab, Kelp crab, Spider crab, Graceful rock crab, Slender kelp crab

Synonyms: Pugettia lordii, Pugettia quadridens var gracilis
Phylum Arthropoda
 Subphylum Crustacea
  Class Malacostraca
   Subclass Eumalacostraca
    Superorder Eucarida
     Order Decapoda
      Suborder Pleocyemata
       Infraorder Brachyura (true crabs)
        Family Majidae
A small Pugettia gracilis. Carapace width about 2.5 cm
(Photo by: Dave Cowles, July 2006)
Description:  The rostrum of this small majid crab consists of 2 flattened processes which diverge from the base.  The carapace is longer than wide.  It has a prominent, sharp lateral tooth near the middle of the carapace, and another wide, flattened lateral projection anterior to the middle.  The dorsal surface of the carapace has tubercles.  The distance between the eyes is about 1/2 the carapace width.  The dorsal surface of the merus of the cheliped has a distinct ridge (photo) in males, but less distinct in females (photo).  Carapace width to 4 cm in males, 2.8 cm in females.  Highly variable in color; often brown, yellow, or red but sometimes white, orange, pink, or blue.  The walking legs often have light-colored bands.  The chelae are bright blue near the end, with orange or red (occasionally white) tips (photo).

How to Distinguish from Similar Species: Pugettia richii (mostly on the open coast) has a narrower anterolateral tooth, plus does not have a distinct ridge of tubercles on the merus of the cheliped and does not have the orange and blue tips on the chelae. Oregonia gracilis has a longer rostrum, about half the length of the carapace, consisting of 2 spinelike processes instead of flattened ones.  It also decorates itself, which this species usually does not do.  Cancer gracilis is a cancer crab. Pugettia producta grows much larger and has a smooth dorsal carapace surface.

Geographical Range:  Attu Island (Aleutian Islands, Alaska) to Monterey Bay, CA.  Common in Monterey Bay.

Depth Range:  Low intertidal (on rocky shores) to 140 m.  Young are often among eelgrass.

Habitat:  Eelgrass and kelp; both on outer coast and on protected shores.  Also on pilings in strong currents.

Biology/Natural History:  The spines on the legs may help this crab hang onto the kelp and avoid being swept off.  This crab does not usually decorate itself much, but it does so occasionally.  Predators include halibut, clingfish, kelpfish, and woolly sculpin.  During mating, the male lies on its back and the female stands above, facing him.  Ovigerous females have been found through most of the year in Puget Sound.  Females have around 6200 to 13,000 eggs per brood.  The long legs of this crab are especially agile, and they can reach far above and behind them for defense.



 
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References:

Dichotomous Keys:
  Coffin, 1952
  Flora and Fairbanks, 1966
  Hart, 1982
  Kozloff 1987, 1996
  Smith and Carlton, 1975
  Wicksten, 2009

General References:
  Carefoot, 1977
  Harbo, 1999
  Johnson and Snook, 1955
  Kozloff, 1993
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:
 Lutts, Donald Jr., 1960.  Laboratory culture methods and larval stages of Pugettia gracilis (Dana).  Masters thesis, Walla Walla College.  37 pp.

Web sites:



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


A female Pugettia gracilis (one rostral horn is broken). Carapace width about 2.5 cm



The merus of the cheliped has a distinct ridge (in males), with teeth, on its dorsal surface.  This is a male.  See the photo below for another view.


In this view of a male the ridge on the merus of the cheliped (lighter colored in the photo above) can be clearly seen.



In females such as this individual, the ridge on the merus is more broken up.



The chelae are blue near the end, with orange or white tips.
 


The abdomen of females, as in this individual, is very broad. This female (same as the one to the left) is carrying eggs.  Often they carry more eggs than this.
Note that the females carry their eggs attached to their uropods, is is characteristic of most members of suborder Pleocyemata.  Male Brachyurans don't have pleopods except for the first pair which is used in copulation.



Authors and Editors of Page:
Dave Cowles (2005):  Created original page
Edited by Dave Cowles 2006