Neotrypaea californiensis (Dana, 1854) Common name(s): Bay ghost shrimp, Ghost shrimp, Red ghost shrimp, Pink mud shrimp
Synonyms: Callianassa californiensis
Phylum Arthropoda Subphylum Crustacea Class Malacostraca Subclass Eumalacostraca Superorder Eucarida Order Decapoda Suborder Pleocyemata Infraorder Thalassinidea Superfamily Callianassoidea Family Callianassidae
	Neotrypaea californiensis, about 7 cm long, from Freeland beach, Holmes Harbor, Whidbey Island, WA.
	(Photo by: Dave Cowles, July 2007)

How to Distinguish from Similar Species: N. gigas has a sharp rostrum, the large cheliped has no gap between the propodus and dactyl, and the carpus of the smaller cheliped is not much wider than the merus. N. affinis has rounded tips on the eyestalks and lives in California. Upogebia pugettensis has a broad rostrum that is hairy dorsally and divided into 3 teeth; its chelipeds are subchelate and of nearly equal size.

Geographical Range:  Southern Alaska to Baja California

Depth Range:  Intertidal, especially middle intertidal

Habitat:  Intertidal in muddy sand.  In areas of compact mud the burrow entrances may appear as small "volcanoes" on the surface

Biology/Natural History:  Ghost shrimp make extensive, branching burrows in sand, burrowing down to .75 m depth.  The burrows generally have more than one entrance, and the animal can often be found near the entrance pumping water into the burrow by beating their large pleopods during low oxygen conditions.  They can survive anoxia for nearly 6 days.  They constantly maintain and remodel their burrows, resulting in major overturn of sediments in areas where they are abundant similar to that accomplished by earthworms in terrestrial areas.  They tolerate a wide range of salinities from on quarter seawater's salinity to substantially saltier than the ocean, though they are not as tolerant of low salinity as is Upogebia.    They feed on detritus filtered from the water and sifted from the substrate by the hairs on their second and third legs.  Breeding is year-round in California but egg-carrying females are most common in June and July.  The larvae may remain planktonic for as long as 8 weeks.  Likely because of this, individuals sampled from Washington all the way to California seem to be relatively homogeneous genetically.  They may live as long as 16 years.

Predators include fish such as staghorn sculpin.  Commensals in the burrow include the polychaete scaleworm Hesperonoe complanata, the snapping shrimps Betaeus harrimani and B. ensenadensis, and the pea crabs Scleroplax granulata, Pinnixia franciscana, and P. schmitti, the burrowing clam Cryptomya californica, and the goby Clevelandia.  Commensals on the animal include the copepods Clausidium vancouverense and Hemicyclops thysanotus, as well as the parasitic isopod Ione cornuta on the gills.

References:

General References:
  Harbo, 1999
  Jensen, 1995
  Johnson and Snook, 1955
  Kozloff, 1993
  Morris et al., 1980
  Niesen, 1994
  Niesen, 1997
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:

Dumbauld, B.R., D. A. Armstrong, and K. L. Feldman, 1996.  Life-history characteristics of two sympatric thalassinidean shrimps, Neotrypaea californiensis and Upogebia pugettensis, with implications for oyster culture.  Journal of Crustacean Biology 16: 689-708

Posey, M. H., 1986.  Changes in a benthic community associated with dense beds of a burrowing deposit feeder, Callianassa californiensis.  Marine Ecology Progress Series 31: 15-22

Web sites:

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

I have not found these in Padilla Bay, though they can be found in the sandier muds of Useless Bay and Holmes Harbor.
 

The rostrum is a broad and bluntly rounded tooth.  The eyestalks are flattened, and the eyes (cornea) appear as dark patches mid-dorsally on the eyestalk

There is a gap between the propodus and dactyl on the large chela.  In this case the large chela is the left one but it may be the left or the right.
The hairs on the legs are used for sifting food from the substrate.
 

In this view one can see that the carpus of the small cheliped (foreground) is wider than is the merus.  The propodus and dactyl are below and slightly out of focus; and the large chela is in the background.

As a Thalassinidean, Neotrypaea californiensis has a broad abdomen and a well-developed tailfan.