Paracrangon echinata Dana, 1852

Common name(s): Horned shrimp
Synonyms:
Phylum Arthropoda
 Subphylum Crustacea
  Class Malacostraca
    Subclass Eumalacostraca
     Superorder Eucarida
      Order Decapoda
        Suborder Pleocyemata
         Infraorder Caridea
          Family Crangonidae
Paracrangon echinata captured at 100 m depth in San Juan Channel.
The arched posture with spines exposed is a typical defense "cataleptic" posture.
Length about 6 cm.
(Photo by: Dave Cowles July 1997)
Description:  Like all crangonids, pereopod 3 is subchelate.  Unlike most crangonids, this species has only 4 pairs of legs (it lacks the second pair of walking legs) and a long, toothed rostrum (see picture above).  Length to about 7 cm.

How to Distinguish from Similar Species: This is the only crangonid with a long spiny rostrum and only 4 pairs of walking legs.  In the same trawls that we catch this species in we also catch the Hippolytid shrimp Lebbeus groenlandicus, which is also reddish marked and spiny and looks superficially similar.  However, L. groenlandicus' reddish markings are in distinct, uneven transverse bands on the abdomen, and it does not as readily assume the cataleptic posture seen in the photo above.

Geographical Range: Port Etches, Alaska to La Jolla, CA

Depth Range: 7-201 m

Habitat: Lives among hydroids, bryozoans, and worm tubes on mixed composition bottoms.

Biology/Natural History: Unlike most crangonids, this species does not bury in the sediment. Feeds on smaller crustaceans and worms that are ambushed and swallowed whole.  The slender third pereopods are held just above the bottom and function as antennas to detect prey, which are seized and attacked with the subchelate first pereopods.  Prey items include gammarid amphipods, shrimp, and polychaetes.  Small prey are consumed whole.  Large prey are first repeatedly speared with the sharp spine on the first pereiopod, then eaten headfirst.  In development, Paracrangon has fewer zoeal stages (only 2 brief, nonfeeding instars) than do many other decapods.

Many members of family Crangonidae burrow into the sand but this species does not.  All members of genus Paracrangon lack the second pereiopods (walking legs).  Since the second pereiopod is often used for grooming, it is not surprising to find parts of this species fouled with hydroids, diatoms, etc.  This may help camouflage them.


 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
  Wicksten, 2009

General References:
  Jensen, 1995

Scientific Articles:
Jensen, Gregory C., 2011.  Feeding behavior of the horned shrimp, Paracrangon echinata (Caridea: Crangonidae).  Journal of Crustacean Biology 31:2 pp. 246-248
 


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

We frequently catch this species at 100 m by otter trawl in the San Juan Channel, on a sandy bottom covered with shell hash.

Beware of putting this species into a tank with others.  Especially at night it will attack other species such as shrimp as large as itself and chop them into pieces.
 
 


Closeup of Paracrangon echinata head showing the spiny rostrum.  Photo by Dave Cowles, July 2005


A dorsal view shows that there are plenty of stiff spines sticking out to the sides, as well.  Photo by Dave Cowles, July 2005



The chelae of this species are subchelate.  This is the right chela.  Length about 2 mm.  Photo by Dave Cowles, July 2005


This species has many tiny greenish eggs, which it carries on the pleopods under the abdomen as visible in this ventral photo.


Authors and Editors of Page:
Dave Cowles (2005):  Created original page