California Spot Prawn

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.

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.

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.

This large benthic shrimp has the typical multiarticulated second pereopod and long rostrum characteristic of family Pandalidae. Antenna 1 is only about as long as the carapace. Abdominal segment 3 does not have a median dorsal ridge and spine. Only the anterior half of the carapace has median dorsal spines. Abdominal segment 6 is less than twice as long as wide. This species is reddish with longitudinal white stripes on the carapace and a distinctive white spot on the sides of the first and fifth abdominal segments. 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.

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 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