Upogebia pugettensis (Dana, 1852) Common name(s): Blue mud shrimp, marine crayfish
Synonyms:  Gebia pugettensis, Gebia californica
Phylum Arthropoda  Subphylum Crustacea   Class Malacostraca    Subclass Eumalacostraca     Superorder Eucarida      Order Decapoda       Suborder Pleocyemata        Infraorder Thalassinidea         Family Upogebiidae
	Upogebia pugettensis from Padilla Bay.  Total length approx. 8 cm.
	(Photo by: Dave Cowles, July 2005)

How to Distinguish from Similar Species: This is the only member of its family found near Rosario.  Neotrypaea (formerly Callianassa) californiensis is the local species which looks most similar, but Neotrypaea has a non-hairy rostrum of one small tooth and chelate chelipeds which are decidedly unequal in size.  Up to 150 mm long.

Geographical Range: Valdez Narrows, Alaska to Morro Bay, CA (S of Morro Bay a nearly identical species, U. macginitieorum is found)

Depth Range: Mostly intertidal

Habitat: Mud flats

Biology/Natural History:  This species lives in pairs in permanent, U- or Y-shaped burrows in mud flats, usually lower in the intertidal and in muddier areas than does Neotrypaea.  The burrows usually have several entrances, and may connect horizontally to the burrow of nearby mud shrimp.  For burrowing they carry mud in a "basket" formed by the first two pairs of thoracic legs.  Once removed from the burrow as adults they do not seem to be able to dig another one.  They feed on suspended detritus carried into their burrow by the beating of their pleopods and captured by their hairy first two pairs of thoracic legs.  The fifth pair of legs is used both for walking (with legs 3-4) and for cleaning the body (plus the eggs of females).  Many commensals such as the northern hooded shrimp Betaeus harrimani, the snapping shrimps Betaeus ensenadensis and B. longidactylus, Scleroplax granulata, the crab Scleroplax granulata, the pea crabs Pinnixia franciscana and P. schmitti, the scale worm Hesperonoe complanata, the clam Cryptomya californica, the phoronid Phoronis pallida, and the arrow goby Clevelandia ios live in the burrows.  Upogebia also seems to have many parasites including an isopod which frequently lives in the gill chambers of specimens from Padilla Bay, the clam Pseudopythina (formerly Orobitella) rugifera which lives attached to the pleopods (picture), and the isopod  Phyllodurus abdominalis, which also attaches to the pleopods. The copepod Clausidium vancouverense lives on the outside of the body.  Upogebia lays yellow eggs in fall which do not hatch until spring.  Predators include Pacific staghorn sculpin Leptocottus armatus.  Mud shrimp disrupt commercial oyster beds and smother the oysters. This species can tolerate brackish water down to 10% of seawater salinity, by osmoregulation.

In a study in Oregon's Yaquina Bay where Upogebia pugettensis is very abundant, 57% of males and 80% of females were infested with the parasitic, blood-sucking bopyrid isopod Orthione griffinis (Smith et al., 2008)  Infestation was especially prevalent among larger Upogebia and in females.  Infested hosts were an average of 7.8% lower weight than similar-sized uninfested hosts.  Burrowing by the species increased remineralization of carbon compounds in the sediment by up to 2.9 times, ammonification by up to 7 times, nitrification by 3 to 9 times, denitrification by up to 4 times, and up to a 15-fold increase in flux of dissolved inorganic nitrogen.

References:

General References:
Brusca and Brusca, 1978
Harbo, 1999
Johnson and Snook, 1955
Morris et al., 1980
Niesen, 1994
Niesen, 1997
O'Clair and O'Clair, 1997
Ricketts et al., 1985
Sept, 1999

Scientific Articles:

D'Andrea, Anthony F. and Theodore H. DeWitt, 2009.  Geochemical ecosystem engineering by the mud shrimp Upogebia pugettensis (Crustacea: Thalassinidae) in Yaquina Bay, Oregon:  Density-dependent effects on organic matter reminaralization and nutrient cycling.  Limnology and Oceanography 54:6 pp. 1911-1932

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

Griffen, B. D., T. H. DeWitt, and C. Langdon, 2004.  Particle removal rates by the mud shrimp Upogebia pugettensis, its burrow, and a commensal clam:  effects on estuarine phytoplankton abundance.  Marine Ecology Progress Series 269: 223-236

Markham, John C., 2004.  New species and records of Bopyridae (Crustacea: Isopoda) infesting species of the genus Upogebia (Crustacea: Decapoda: Upogebiidae): the genera Orthione Markham, 1988, and Gyge Cornalia & Panceri, 1861. Proceedings of the Biological Society of Washington 117(2): 186-198 (describes an isopod parasite, Orthione griffenis, from the gills of Upogebia in Oregon)

Posey, M. H., B. R. Dumbauld, and D. A. Armstrong, 1991.  Effects of a burrowing mud shrimp, Upogebia pugettensis (Dana) on abundances of macro-fauna.  Journal of Experimental Marine Biology and Ecology 148: 283-294

Smith, Andrew E., John W. Chapman, and Brett R. Dumbauld, 2008.  Population structure and energetics of the bopyrid isopod parasite Orthione griffinis in mud shrimp Upogebia pugettensis.  Journal of Crustacean Biology 28(2): 228-233
 
 

Medial view of left chela, open.  Note the abundant setae on the dorsal and lateral sides of the chela.  Note also that the propodus has a small, fixed projection on the ventral side of the end.	Lateral view of the left chela, open.  The setae obscure part of the the structure.	Lateral view of left chela, closed.  Note that the chela is subchelate, because the dactyl folds down across the end of the propodus.  The dactyl fits just medial to the ventral projection on the propodus.
The chelae of Upogebia pugettensis are subchelate.  The dactyl folds down across the end of the propodus and beside a fixed projection on the end of the propodus, as can be seen in the photos above.

Upogebia is often parasitized by a clam, Pseudopythina (Orobitella) rugifera, which clings to a ventral part, usually a pleopod.  It is said to attach by a byssal thread.
An unknown parasitic isopod is living in the right gill chamber of this specimen.  Markham (2004) newly described a parasitic isopod Orthione griffenis Markham, 2004 which lives in the gill chambers of Upogebia,
so perhaps that is the species name here.

Photo by Dave Cowles, July 2005