Rossia pacifica (Berry, 1911)

Stubby Squid, Short Squid 
Synonyms: None
Phylum Mollusca
 Class Cephalopoda
  Subclass Coleoidea
   Superorder Decabrachia
    Order Sepiolida
     Family Sepiolidae 
Found in Friday Harbor, WA.  Picture taken at Rosario Beach Marine Station, WA
Photo by: Robbie Wheeling, July 22, 2002 
Description:  The maximum dorsal mantle length is about 5 cm in females and about 3-4 cm in males.  The total length (including arms but not tentacles) of females is about 11 cm, of males is about 9 cm.  The mantle is 1.5-2 times as lng as it is wide, flattened above and below, rounded behind, and it is not fused to the head in the front.  The fins are round with broad free lobes, almost as long as the mantle.  The head is large and the arms lengths are variable.  Usually the dorsal arms are the shortest and the third arms are the longest.  The arm suckers are arranged in two rows in the proximal and distal portions of each arm, and in two, three, and four rows in the middle portion.  The suckers are alike in size on all arms except those of the dorsal arms of the male, which are hectocotylized with much smaller suckers.  The tentacles may be retracted or extended longer than the body.  The rentacles have slender terminal clubs bearing centrally up to eight partial rows of small suckers.  Their color in life is a reddish brown above and pale below, or wholly opalescent greenish gray if disturbed.

How to Distinguish from Similar Species:  No similar species.

Geographical Range:  This species ranges is along the north Pacific rim from Japan to southern California.

Depth Range:  This species is benthic in coastal waters, subtidal (16-370 m) but on rare occasions at night found swimming at the shore in the intertidal zone.

Habitat:  This species is fairly common on bottoms of sand or muddy sand.

Biology/Natural History:  These small sepiolids crawl on their arms or swim, and dig shalow depressions in the sea floor, in which they rest wit htheir arms rolled under their heads.  They inhabit shrimp beds; over 80% of their diet consists of shrimp, although crabs, mysids, small fishes, and cephalopods are also eaten.  Spawning occurs in the summer and fall in deep water.  Each egg (4-5 mm in diameter) is contained in a large (8 mm by 15 mm) capsule.  The capsules are attached singly or in small groups to seaweeds or other objects on the bottom.


 
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References:

Dichotomous Keys:
   Kozloff, 1987

General References:
   Morris et al., 1980

Scientific Articles:


General Notes and Observations:  Locations, abundances, unusual behaviors, etc.:
Nine species of dicyemid mesozoans have been recorded from the kidneys and branchial hearts of R. pacifica.  Of these, only two are known to occur off the west coast: Dicyemennea brevicephaloides and D. parva.
 

Rossia

This individual, with body length about 7 cm long not including tentacles, was also collected by otter trawl  in the San Juan Channel.  Photo August 2011 by Dave Cowles


Authors and Editors of Page:
Anna Dyer (2002):  Created original page
Edited by Hans Helmstetler 12-2002, Dave Cowles 2005