Idotea ochotensis Brandt, 1851

Common name(s): 

Phylum Arthropoda
 Subphylum Crustacea 
  Class Malacostraca
   Subclass Eumalacostraca
    Superorder Peracarida
     Order Isopoda
      Suborder Valvifera
       Family Idoteidae
Idotea ochotensis on 3rd Beach, Olympic Peninsula, WA
(Photo by: Dave Cowles, July 2006)
Description:  As with other valviferan isopods, the uropods are ventral to the pleotelson, forming a valvelike covering over the pleopods (photo). Idotea ochotensis has a body which is definitely dorsoventrally flattened and with 7 free pereonites.  The lateral margins of the cephalon do not have a deep incision.  The eyes are lateral.  The pleon has 2 free pleonites plus a pleotelson (which has a pair of lateral incisions showing the margin of a third partly free pleonite).  The pleon has a definite point on the posteromedian margin.  The lataral margins of the pleon, and the posterior margins of the pleon on either side of the posteromedian point are often concave.  The palp of the maxilliped has only 4 articles. Length to 4.2 cm, width to 1.6 cm.

How to Distinguish from Similar Species:  Idotea aculeata is very similar but the palp of its maxilliped has 5 articles and it is found only from central California south.  Idotea resecata has a concave posterior margin on the pleotelson.

Geographical Range:  Japan, NE Asia to San Francisco

Depth Range:  At least intertidal and shallow subtidal

Habitat:  We found this individual in an area of mixed boulders and sand, in an area with strong surf.  Sometimes found on drifting seaweed and in brackish water.

Biology/Natural History:

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Dichotomous Keys:
  Kozloff 1987, 1996

General References:
  Johnson and Snook, 1955

Scientific Articles:

Web sites:

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

The underside of the same individual as above.

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