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)
Kozloff 1987, 1996
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
studied in this thesis was the mantis shrimp Hemisquilla
the control species was Pandalus platyceros.
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.
Authors and Editors of Page:
Dave Cowles (2005): Created original page