Caprella angusta Mayer, 1903 

Common name(s):  Skeleton shrimp

Synonyms:   Smith and Carlton (1975) state that Caprella uniforma is probably a junior synonym.  ITIS does not list C. angusta at all but does list C. augusta with no range information. (Caprella angusta
Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca
Subclass Peracarida
Order Amphipoda
Suborder Caprellidea
Infraorder Caprellida
Family Caprellidae
Caprella angusta from eelgrass in Padilla Bay.  Total length about 4 cm.  One of the ventral flaplike gills is visible posterior to the large grasping gnathopods 2, right at the end of the eelgrass.
(Photo by: Dave Cowles, July 2008)
Description:   This freeliving caprellid amphipod has gills on only pereonites 3 and 4 (not on pereonite 2).  It has no pereopods on pereonites 3 and 4.  Gnathopod 2 (the large set) has a propodus which is less than 2/3 as wide as it is long (photo), and the propodus of pereopods 5-7(the back legs, with which it grasps the substrate) (photo) has only one grasping spine or tooth (Smith and Carlton 1975 says there are two or more).  There is no spine on the ventral body surface between gnathopods 2 (photo), but there is a large, dorsal, anteriorly directed triangular spine on the back of the head (photo).  It has few or no tubercles on the dorsal surface of the pereonites, and none on pereonite 1.  Gnathopod 2 of the male is attached at the anterior end of pereonite 2.

How to Distinguish from Similar Species: Tritella pilimana has a vestigial pereopod on pereonites 3 and 4, while Caprella angusta does not.  Several other members of genus Caprella either do not have the large triangular spine on the dorsal side of the head, or also have large dorsal tubercles on their pereonites and gnathopod 2 is attached near the middle of pereonite 2.

Geographical Range:

Depth Range:


Biology/Natural History:  Caprellid amphipods such as this species are roving predators.  We often find them climbing on eelgrass or hydroids searching for prey.  With their large claws (gnathopods) and bizarre shape they would truly be monsters if they were our size!



Dichotomous Keys:
  Kozloff 1987, 1996
  Smith and Carlton (1975) (as C. uniforma)

General References:

Scientific Articles:

Web sites:

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

Pereopods 5-7
This closeup shows pereonites 5-7 with their appendages, pereopods 5-7.  Pereopods 5-7 arise from the posterior end of their segment (pereonite) and are used for gripping the substrate such as this eelgrass blade.  The left pereopod 7 is missing.

Gnathopod and gill
The propodus of gnathopod 2 is less than 2/3 as wide as it is long.  Note also the gill on the segment behind.

Ventral view
This ventral view shows there is no spine between the large gnathopods 2  and shows the location of the gills.


This view of the head (animal is looking to the left) shows the very large second antennae to the left, then the head with sessile eyes and prominent, forward-directed head spine.  Below the head can be seen the first gnathopods which are on the anterior end of the first thoracic segment (pereonite), which extends out of view to the right.

Authors and Editors of Page:
Dave Cowles (2008):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)