Pandalus tridens Rathbun, 1902

Common name(s): Yellowleg pandalid
Synonyms:  Pandalus montagui tridens P. tridens
Phylum Arthropoda 
Subphylum Crustacea 
Class Malacostraca 
Subclass Eumalacostraca 
Superorder Eucarida 
Order Decapoda 
Pandalus tridens from the Sea of Okhotsk, NW Pacific.
(Photo by: Andrey Gontchar )
Description:   This moderately large shrimp has the multiarticulated carpus on its second pereopod and the long rostrum characteristic of Pandalids.  Its first antenna is only about as long or slightly longer than its carapace (including the rostrum).  Abdominal segment 3 is not compressed and does not have a median dorsal ridge or mid-dorsal spine anterior to the posterior edge.  The carapace has mid-dorsal spines only on the anterior half.  The rostrum does not have mid-dorsal spines on the distal half (though it does have ventral spines), and it ends in three points (trifid).  Abdominal segment 6 is about 3x as long as wide.  Body color consists of fine red dots over a translucent background, with darker red background on distal rostrum, base of antenna, pleopods, side of sixth abdominal segment, and dorsal surface of uropods and telson.  Up to 12.3 cm long.

How to Distinguish from Similar Species:P. platyceros has an abdominal segment less than twice as long as wide. P. eous, P. jordani, and P. goniurus don't have the steeply ascending rostrum with the three pointed (trifid) tip.  They also have a medial dorsal ridge on abdominal segment 3.  This is the only pandalid shrimp in this area which has light bands on its legs but no stripes or spots on the body.

Geographical Range:   West side of Bering Sea and Sea of Okhotsk to Channel Islands off Santa Barbara, CA.

Depth Range:  5-1984 m

Habitat:  Rocky and muddy bottoms, may be more common on rocky bottoms.

Biology/Natural History:
This species was early identified as P. montagui tridens, a Bering Sea variation of the Atlantic P. montagui.  However, the larvae differ in several reliable anatomic respects from those of P. montagui and the adults are colored differently, leading P. tridens to be given full species status.  Except for the difference in coloration and the fact that the rostrum of P. montagui ends in 2 points and that of P. tridens ends in 3, the adults of these two species are almost indistinguishable. P. tridens tends to have more rostral spines but the counts overlap.  P. tridens also has shorter dactyls than does P. montagui.

The isopod Bopyroides hippolytes infests the gills of this species but does not infest P. montagui.  It may also be parasitized by the Rhizocephalon barnacle Sylon hippolytes.

This species is a protandroushermaphrodite (is a male first, then later becomes female).  It appears to change from male to female at about 1 1/2 to 2 years old.  In the Strait of Georgia females may be ovigerous (carrying eggs) from late November to early April.


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References:

Dichotomous Keys:
  Kozloff, 1987, 1996

General References:
  Butler, 1980
  Jensen, 1995
  Lamb and Hanby, 2005

Scientific Articles:

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:
Dorsal view
This dorsal view is also by Andrey Gontchar.  This individual, which is the same as the one at the top of the page, is a mature female.  It was collected at about 300 m depth in the Sea of Okhotsk, near southwestern Kamchatka.


Authors and Editors of Page:
Dave Cowles (2009):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)

Rosario Invertebrates web site provided courtesy of Walla Walla University