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 0.75 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, and green sturgeon in estuaries such as Willipa Bay (Borin et al., 2017).  Commensals in the burrow include the polychaete scaleworm Hesperonoe complanata, the snapping shrimps Betaeus harrimani and B. ensenadensis, and the pea crabs Scleroplax granulata, Pinnixa franciscana, and P. schmitti, the burrowing clam Cryptomya californica, and the goby Clevelandia sp.  Commensals on the animal include the copepods Clausidium vancouverense and Hemicyclops thysanotus on the gills, as well as the parasitic isopod Ione cornuta. 

The burrows of Neotrypaea californiensis can be distinguished from those of Upogebia pugettensis by the following characteristics (Chapman and Carter, 2014):  Neotrypaea burrows have multiple connected openings, are not constricted at the entrance, and have rough linings to the walls.  Upogebia burrows, on the other hand, typically have paired, connected entrances which are constricted at the entrance, and the burrow walls are quite smooth.  In addition, in my experience Neotrypaea burrows are more common in sandy/gravelly areas, while Upogebia burrows are more common in finer sediment.

According to work done by John Durban, Holly Fearnbach, and John Calambokidis and reported by the Seattle Times and the Feb. 17, 2021 Walla Walla Union-Bulletin, , a group of about a dozen gray whales nicknamed "The Sounders" appears to have developed a new feeding strategy: On their spring northward migration from the Baja California calving lagoons they enter Puget Sound and swim to the mouth of the Skokomish river near Everett, whic is about a 170-mile detour from their open coastal route. There they wait for high tide, then swim across the shallow mud flat area scooping up sediment in their baleen and separating out the ghost shrimp to eat. Within three weeks they can be observed to plump up noticeably. They swim up to a mile into the mud flats feeding in water only 7 to 9 feet deep, which could quickly become hazardous for them as soon as the tide begins to go out. The feeding pits they produce are about 6 feet long and 2 feet wide. The group of whales is a fairly cohesive one, with several members returning since the early 1990's although new whales have been sighted as well.

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:

Borin, J.M., M.L. Moser, A.G. Hansen, D.A. Beauchamp, S.C. Corbett, B.R. Dumbauld, C. Pruite, J.L. Ruesink, and C. Donoghue, 2017. Energetic requirements of green sturgeon (Acipenser medirostris) feeding on burrowing shrimp (Neotrypaea californiensis) in estuaries: importance of temperature, reproductive investment, and residence time. Environ. Biol. Fish. (2017): 1-13. DOI: 10.1007/s10641-017-0665-3

Chapman, John W., and Cameron S. Carter, 2014.  A rapid intertidal megafauna survey method applied to Upogebia pugettensis, and its introduced parasite, Orthione griffensis.  Journal of Crustacean Biology 34:3 pp 349-356

Dumbauld, B.R., and S. Wylie-Echeverria, 2003.  The influence of burrowing thalassinid shrimps on the distribution of intertidal seagrasses in Willapa Bay, Washington, USA.  Aquatic Botany 77: 27-42

Pernet, Bruno, Aimee Deconinck, and Lisa Haney, 2010.  Molecular and morphological markers for distinguishing the sympatric intertidal ghost shrimp Neotrypaea californiensis and N. gigas in the eastern Pacific.  Journal of Crustacean Biology 30:2 323-331

Pernet, B., A. Deconinck, A. Llaban, and J. Archie, 2008.  Evaluating risks associated with transport of the ghost shrimp Neotrypaea californiensis as live bait.  Marine Biology 153: 1127-1140

        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: 

Newspaper article: Mapes, Lynda V., 2021 (Seattle Times). Gray whales learn feedng strategy in Puget Sound: Digging for shrimp at high tide. Article on page A2 of the Walla Walla Union Bulletin, February 17, 2021.

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. 

This 8 cm individual, collected from the beach at Freeland, has many individuals of the red parasitic Poecilostomatoid copepod Clausidium vancouverense running around in its gill chamber. Photo by Dave Cowles, July 2020.