Pandalus platyceros Brandt, 1851

Common name(s): Spot shrimp, Spot prawn*

Synonyms:
Phylum Crustacea 
 Subphylum Crustacea 
  Class Malacostraca 
   Subclass Eumalacostraca 
    Superorder Eucarida 
     Order Decapoda 
      Suborder Pleocyemata
        Infraorder Caridea (true shrimp) 
         Family Pandalidae
Pandalus platyceros from 100 m depth in San Juan Channel.  Length about 20 cm
(Photo by: Dave Cowles July 2004)
Description:  This large benthic shrimp (up to 25 cm long) has the typical multiarticulated second pereopod (photo) and long rostrum (1.2 to 2x the carapace length for this species) characteristic of family Pandalidae (photo).  Antenna 1 is only about as long as the carapace.  Abdominal segment 3 does not have a median dorsal ridge and spine (photo).  Only the anterior half of the carapace has median dorsal spines (photo).  Abdominal segment 6 is less than twice as long as wide (photo).  This species is reddish with longitudinal white stripes on the carapace (photo) and a distinctive white spot on the sides of the first and fifth abdominal segments (photo).  Their pereopods and antennae are banded dark red and lighter red or white. Juveniles may be red, or may be brown or green.  The abdomen is smooth and shiny but the carapace is covered with a fuzzy layer of short, fine setae.

How to Distinguish from Similar Species: This is the largest shrimp on the west coast of North America.  The large size and white spot on the abdomen are distinctive.  Pandalus tridens has a 6th abdominal segment 3 times as long as wide.

Geographical Range: Unalaska, Alaska to San Diego, CA; Sea of Japan and Korea Strait

Depth Range: Low intertidal to 487 meters.  Mostly well below the intertidal zone.

Habitat: Subtidal rocky and sandy habitats.  We frequently catch them on by otter trawl in the San Juan Channel on bottoms of shelly hash.  Juveniles come shallower, even into the lower intertidal zone where they hide in crevices and under boulders during the day.

Biology/Natural History: A common inhabitant of deep sandy bottoms in the Rosario area.  Feed on crustaceans, polychaetes, limpets, and carcasses.  One important predator is the giant octopus Octopus dofleini and the yelloweye rockfish Sebastes ruberrimus.  One interesting feature about this species is that it has a different number of  multiarticulations on the carpus of its two second pereopods:  The left pereopod has 27-31 articles and is longer, while the shorter right second pereopod has only 8 or 9 articles on the carpus.  Breeding ends in late October.  Females carry their eggs on the abdomen for 4-5 months, remain in deep water.  Eggs hatch in March or April.  Larvae settle from the plankton in May and June.  Juveniles feed in shallow water during summer, especially among Agarum fimbriatum and A. clathratum kelp.  They seem to avoid Laminaria saccharina.  During their second fall (carapace length 2.8 cm) they become males, which they remain until they grow to 3.3 cm carapace length, at which time they become females.  Females may mate only once.  May not live longer than 4 years.  These shrimp are very common on the bottom in the deeper portions of the Salish Sea.  At depths over 70 m in the Salish Sea area they aggregate on shallow-slope bottoms near deposits of drift kelp, on which they feed (Britton-Simmons et al., 2012)



 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
  Wicksten, 2009

General References:
  Lamb and Hanby, 2005
  O'Clair and O'Clair, 1998

Scientific Articles:

Britton-Simmons, Kevin H., Alison L. Rhoades, Robert E. Pacunski, Aaron W.E. Galloway, Alexander T. Lowe, Elizabeth A. Sosik, Megan N. Dethier, and David O. Duggins, 2012.  Habitat and bathymetry influence the landscape-scale distribution and abundance of drift macrophytes and associated invertebrates.  Limnology and Oceanography 57:1 pp. 176-184

Komai, T., 1999.  A revision of the genus Pandalus (Crustacea: Decapoda: Caridea: Pandalidae).  Journal of Natural History 33: pp 1265-1372

McFadden, Melissa A., 2004.  Living without oxygen:  The anaerobic metabolism of Hemisquilla californiensis.  M.S. thesis, Walla Walla College Dept. of Biology.  58 pp.  Though the primary species studied in this thesis was the mantis shrimp Hemisquilla californiensis, the control species was Pandalus platyceros.  The abstract follows:
Hemisquilla californiensis (Stomatopoda: Hemisquillidae) is a burrow-dwelling mantis shrimp that routinely encounters hypoxic conditions and can survive more than 48 hours in complete anoxia.  We compared the properties of this species' tissue and hemolymph to those of the spot shrimp Pandalus platyceros (Caridea: Pandalidae), which inhabits an aerobic environment and dies within a few hours of anoxia, to find the biochemical adaptations that allow Hemisquilla to survive in low oxygen.  Both species accumulated lactate under anaerobic conditions, with the greatest levels in the hemolymph.  Hemisquilla accumulated lactate more slowly than did Pandalus and tolerated a much higher lactate concentration in the blood before death.  Slightly elevated alanine levels were observed during anoxia in both species.  The buffering capacity of the tissues analyzed in Hemisquilla was no greater than that in Pandalus, providing no added protection against acidification during anaerobiosis.  However, Hemisquilla tolerated a two-fold greater decrease in hemolymph pH before death than did Pandalus.  The capacity for survival in anaerobic conditions shown by Hemisquilla is due both to a mechanism for reducing the rate of lactate buildup in the blood and to an increased tolerance for lactate and acidosis.



General Notes and Observations:  Locations, abundances, unusual behaviors:
*Note on shrimp vs prawns:  In most of the world, members of infraorder Caridea are known as shrimp and members of infraorder Penaeidea are known as prawns.  In the United States, however, these terms are used much more loosely.  Often any shrimplike animal which has a large body and walks along the bottom is called a prawn.  I prefer to use the terms as the rest of the world does since that makes more taxonomic sense.

This species is fished commercially (mainly via shrimp pots) from Alaska to northern California.


Photo by Dave Cowles, July 2000


 


Photo by Dave Cowles, March 2004



The carpus of pereopod 2 is subdivided by many annular striations into a flexible series of many articles.  This structure is called a multiarticulated carpus.
Pandalids have many articles (more than 7) on the carpus of the 2nd pereopod, and usually have around 20.



Pandalus platyceros has a long rostrum which is longer than the rest of the carapace.  It has movable dorsal spines which continue out to at least part of the distal half of the rostrum.



Abdominal segment 3 has no mid-dorsal carina (ridge) or spine.
Note how the pleurite of segment 2 expands and overlaps that of segments 1 and 3, as is characteristic of caridean (true) shrimp.



Abdominal segment 6 is less than twice as long as it is wide.
 


Sylon hippolyte parasitism
This scar on the abdomen is the result of the outgrowth of the externa of the parasitic barnacle Sylon hippolytes.  Photo provided by Hilary Wood of the Alaska Dept. of Fish and Game.



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