Caprella kennerlyi (Stimpson, 1864)

Common name(s): Skeleton shrimp

Synonyms: Metacaprella kennerlyi Caprella kennerlyi
Phylum Arthropoda 
Subphylum Crustacea 
Class Malacostraca 
Subclass Eumalacostraca 
Superorder Peracarida 
Family Caprellidae 
Caprella kennerlyi, apparently a male, found on Fidalgo Bay Marina dock.  Total length 3.5 cm.
(Photo by:  Dave Cowles, July 2014)

Description:  This skeleton shrimp (Caprellid) has two forward-projecting spines on the back of its head.  The articles of the peduncle of antenna 1 are much longer than wide, and the flagellum of the first antenna is shorter than the peduncle (see photo above).  On males, the peduncle of antenna 1 is stout and setose (photo) and the flagellum has less than 20 articles.  Its mandible has a molar process but does not have a palp.  The merus of gnathopod 2 has a sharp, spiny anteroventral projection or a stout, spinelike seta.  The propodus of gnathopod 2 is less than 2/3 as wide as long, and the second gnathopods do not have a ventral spine on the pereonite surface between them.  Pereonites 1 and 2 of males are more than twice as long as wide.  It has gills only on pereonites 3 and 4.  Pereonites 3 and 4 also have several pairs of spines and have oostegites on mature females, but not even rudimentary legs on either sex.  Pereopods 5-7 (the legs near the back) have a single grasping spine or tooth on their propodus.  Females have a rough texture, with spines on all segments.  Has pink spots and bands.

How to Distinguish from Similar Species:  This is an unusually large skeleton shrimp species. Metacaprella anomala has the flagellum of antenna 1 longer than the peduncle and pereonites 1 and 2 of males are not more than twice as long as wide.

Geographical Range:  All along the N American Pacific coast

Depth Range:  Intertidal and subtidal

Habitat:  Many different substrates and fouling communities (first described from a fouling community on a ship in Port Townsend).  Often in Abietenaria hydroid colonies.

Biology/Natural History:  May be especially well-camouflaged on Plumularia lagenifera hydroids.  The setae on the antennae are apparently used to scrape algae off the body.  Filter feeders and detritus eaters scrape their body clean, such as this individual.  Carnivorous predator and scavenger species allow algae to grow on them, presumably to increase their camouflage.



Dichotomous Keys:
  Carlton, 2007
  Kozloff, 1987, 1996 (as Metacaprella kennerlyi)

General References:
  Johnson and Snook, 1955
  Ricketts et al., 1985

Scientific Articles:

Caine, E.A., 1980.  Ecology of two littoral species of caprellids (Crustacea) from Washington, USA.  Marine Biology 56: pp 327-335

Jensen, M.P., 1969.  The ecology and taxonomy of the Caprellidae (Order: Amphipoda; Suborder: Caprellidea) of the Coos Bay, Oregon, area.  Ph.D. dissertation, Department of Entomology, University of Minnesota

Martin, D.M., 1977.  A survey of the family Caprellidae (Crustacea, Amphipoda) from selected sites along the northern California coast.  Bulletin of the Southern California Academy of Sciences 76: pp 146-167

Web sites:

General Notes and Observations: Locations, abundances, unusual behaviors:

Ventral view
This ventral view shows the gills but no legs on pereonites 4 and 5. On the second gnathopods, the merus has an anteroventral spine, the propodus of the second gnathopod is less than 2/3 as wide as long, and the ventral region of the second pereonite between the bases of the second gnathopods is smooth instead of having a tubercle or spine.

First antennae
On males such as this one, the peduncles of the first antennae are robust with many setae, and the antennal  flagellum is shorter than the peduncle.

Head spines
This dorsal view of the head shows the forward-pointing head spines.  The middle spine is lower than the others and may be a piece of debris.

Ventral head view
This ventral view of the head gives a clear view of the mouth, antennae, gnathopods 1 and 2, and pereonites 1-5.

Authors and Editors of Page:
Dave Cowles (2014):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)

Salish Sea Invertebrates web site provided courtesy of Walla Walla University