Betaeus harrimani Rathbun, 1904

Common name(s): Northern hooded shrimp

Phylum Arthropoda
 Subphylum Crustacea
 Class Malacostraca
  Subclass Eumalacostraca
   Superorder Eucarida
    Order Decapoda
     Suborder Pleocyemata
      Infraorder Caridea
       Family Alpheidae
Betaeus harrimani from Royal Palm State Beach, Long Beach, CA.  About 3 cm long.
(Photo by: Dave Cowles April, 1997)
Description:  Caridean sthrimp have the epimeron of the second abdominal segment overlapping that of segments 1 and 3.  Family Alpheidae has the carpus of pereopod 2 subdivided into 3-7 (but not more) units (picture), no rostrum (picture), and eyes at least partly covered dorsally by the carapace (picture). Betaeus harrimani has a convex frontal margin of the carapace with no indentation (picture), and the propodus of its cheliped is more than twice as long as wide (picture).  There is a triangular plate at the base of each uropod.  The inner and outer uropods are similar in length and longer than the telson.  Its body is transparent except where pigmented.  Length to about 35 mm.  Close inspection shows many red pigment cells (chromatophores), often surrounded by dark blue spots.  Appears reddish during the day and dark blue at night.

How to Distinguish from Similar Species: B. setosus has an indentation on the frontal edge of the carapace and the hand of its propodus is about as wide as long.

Geographical Range: Sitka, Alaska to Dana Point, CA

Depth Range: Intertidal, probably also subtidal

Habitat: Under low intertidal rocks, logs, and debris, mostly on protected shores; on mud flats, especially in the burrow of Upogebia pugettensis and Neotrypaea (formerly Callianassa) californiensis.

Biology/Natural History: This is an actively moving and usually well-camouflaged shrimp.  Eggs are bright green.  Females in British Columbia carry eggs from June to September.

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Dichotomous Keys:
  Kozloff 1987, 1996
  Smith and Carlton, 1975
  Wicksten, 2009

General References:
  Jensen, 1995
  Morris et al., 1980
  O'Clair and O'Clair, 1998

Scientific Articles:

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

In this side view, the hood that covers the eyes can be seen.  Animal total length is 3 cm.  Photo by Dave Cowles, July 2005.  Captured in a Upogebia pugettensis burrow.

Photos of features used for identifying this species:

All 5 "walking" legs (pereopods).  Leg 1 = chelae, leg 2 is slender, and the carpus is subdivided into sections (visible in the picture, characteristic of all Alpheids).  Legs 3-5 are for walking.

There is no rostrum nor indentation on B. harrimani--the anterior end of the carapace is rounded.

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