The BC Ghost and Mud

BACKGROUND

The mud shrimps and ghost shrimps , are classified within the Infraorders and . They are more closely related to the then the true (Heard et al. 2007). They construct and live in extensive burrows in soft sediment. Except for a larval phase, which may or may not be pelagic, they generally spend their entire life within the burrow system.

Their burrowing has important effects on sediment characteristics, nutrient cycling, and community composition. Their burrowing can also affect the growth and survival of oysters and other bivalves and is of concern to oyster aquaculturalists in the Pacific Northwest (Dumbauld et al. 1996). Burrowing can stir-up sediment that can then smother some clams. Also, their burrowing changes the porosity (firmness) of the substrate causing oysters to sink into the substrate where they are unable to survive (Griffis and Suchanek 1991).

They are found in estuarine and marine habitats from the intertidal to subtidal, as well as the abyssal depths. Members of this group are vaguely reminiscent of or shrimp. The carapace is somewhat laterally compressed. The abdomen is slightly dorsoventrally compressed and terminates in a well-developed tail fan (Brusca and Brusca 1978). They have five pairs of legs originating from the carapace. The first two pairs of legs, and sometimes the third to fifth are chelate. The first pair of chelae are relatively large and often asymmetrical (Brusca and Brusca 1978). Many of this group have a relatively soft and thin exoskeleton (Heard et al. 2007). They generally have two sexes, though some deep-water species are hermaphroditic. Many species are sexually dimorphic, with males having larger chelae (Dumbauld et al. 1996). Like most decapods they carry their eggs attached to the underside of the abdomen. The timing of reproduction varies, with some species reproducing in the spring and others reproducing in the fall (Dumbauld et al. 1996).

The mud shrimp (family ) and ghost shrimps (family ) are the best studied. These burrowers range from the intertidal zone to the subtidal continental slope. They are active burrowers and deposit feeders. Their burrows provide shelter for other invertebrates, including the shrimp Betaeus ensenadensis, members of the family Pinnotheridae, the clam Cryptomya californica, and the blind goby Typhlogobius californiensis. See MacGinitie and MacGinitie (1968), Morris et al (1980,1992), and Ricketts et al.(1985) for additional information on the natural history of nearshore species.

Little is known of the natural history of the deep-water species. Species of the families , Calocarididae and are found on the continental shelf and slope.

THE KEY

This online taxonomic key is not intended to be a typical dichotomous key. The intent is to present well defined traits that can be easily scored and used in combination in order to arrive at a correct species designation. Species included in the key are those found in the waters of British Columbia. The key is based on the anatomy of mature adult specimens, and males in particular. Its application to immature specimens and sexually dimorphic females may lead to unsatisfactory results. Descriptions, as well as diagrams and illustrations used in the online key, for the most part, follow those of Cowles (2006), Cowles (2007), Hart (1982), Sakai (2006), Williams (1986), and Wicksten (2009). Those interested in more complete descriptions are referred to these works.

All of the species dealt with in this key were once placed in the Infraorder , and were thought to be monophyletic in origin. Recent anatomical studies(Sakai, K. 2004), however, have shown the species to be of diphyletic origin, and hence the designation as Thalassinidea is no longer valid. Based on the new data, these species are now placed in 2 new Infraorders, the Axiidea and the Upogeiidea.

British Colunbia species are shown below.

Infraorder Axiidea

Family Axiidae Calastacus stilirostris Mud Shrimp Calocarides quinqueseriatus Keeled Mud Calocarides spinulicauda Ghost Shrimp Lophaxius rathbunae Mud Shrimp

Family Callianassidae Callianopsis goniophthalma Slope Ghost Shrimp Neotrypaea californiensis Bay Ghost Shrimp Neotrypaea gigas Giant Ghost Shrimp

Infraorder Gebiidea

Family Upogebiidae Upogebia pugettensis Blue Mud Shrimp

ANATOMY - AXIIDEA ANATOMY – GEBIIDEA

GLOSSARY acute: sharply pointed. antenna (antennae): a sensory appendage on the head; two pair of antennae, the first of which are called antennules and the second of which are called the antennae or second antennae. anterolateral: located toward the sides of the front of the . carapace: a continuous covering (often hardened to at least some extent) over the head and thorax; divided into the cephalic (anterior) region and the thoracic region. carina: a ridge. caudal tail fan: a posterior combination of a central telson and two lateral uropods which together comprise a flattened structure at the tail that can be spread out like a fan. cervical: transverse groove between the cephalic and thoracic regions of the carapace. chela (chelae): a pincer in which the dactyl serves as the movable claw and the propodus serves as the stationary claw. chelate: provided with a chela; more specifically, a chelate cheliped is one in which part of the 6th element (propodus) is elongated into a “fixed finger” (pollex) against which the 7th moveable element (dactyl) clamps as a moveable finger [see subchelate]. cheliped: any chela (claw)-bearing thoracopod, but typically refers to first pair(s) of pereopods. dactylus (dactyl): 7th and terminal segment of appendage; follows propodus and may serve as a distal element in subchela or as a moveable finger in chela. dentate: toothed, having a series of pointed projections like teeth. denticulate: having a series of small tooth-like projections (smaller than dentate). dorsomedial: in the middle of the dorsal side, or toward the middle of the dorsal side. gastric: median region of dorsal carapace between frontal (rostral) region and cardiac ending at the cardiac suture. hermaphroditic: capable of functioning both as a male and a female during its life, with both male and female reproductive organs, either simultaneously or sequentially. linea thalassinica: lengthwise anterolateral grooves on each side of center of the carapace. pereopod: an appendage (leg) arising from a segment of the pereon (thorax); usually used as walking legs; decapods have five pairs of pereopods. pleopod: one of two appendages of each abdominal somite; serves in swimming or variously modified as copulatory structures in male and egg brooding structures in female. pleuron (pleura): the lateral part of the integument (exoskeleton) of a body segment; may form prominent lateral or ventral extensions or plates; attaches dorsally to the tergite and ventrally to the sternite. pollex: prolonged extension of propodus of a chelate limb; the fixed finger of a claw. propodus: 6th segment of appendage, between carpus and dactylus, forming the immoveable portion of the chela. rostrum: an unpaired anterior extension of carapace which projects between the eyestalks and represents an extension of the frontal region of the carapace. serrated: refers to an edge covered with a series of teeth or spines, giving a saw-blade appearance. spatulate: shaped like a spatula or spoon. spine: a stiff, sharp projection, usually with a solid, inflexible base. sternite: the ventral plate of integument (exoskeleton) covering each segment; attaches on the sides to the pleurite. subacute: less than acute. subchelate: pereopod in which the dactyl (article 7) folds back against the palm of the propodus to form a pincer or chela (differing from chelate in that the propodus does not have a distal prolongation or "finger" against which the dactyl closes); a subchelate chela is a claw in which the axis of closure is at nearly a right angle with the long axis of the leg rather than parallel to the long axis of the leg; contrast this term with chelate. subequal: of unequal but nearly equal size. telson: most posterior segment of the body of a ; may form tail fan (caudal fan) together with uropods. tubercle: a small, usually rounded bump or projection. REFERENCES

Cowles, D. 2006. Invertebrates of the Salish Sea. http://www.wallawalla.edu/academics/departments/biology.rosario.inverts.index.html Cowles, D. 2007. Key: Family Callianassidae. www.wallawalla.edu/academics/departments/biology/rosario/inverts/Arthropoda/Crustacea/Malacostr aca/Eumalacostraca/Eucarida//Thalassinidea/Callianassidae_Key.html 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(4): 689-708. Griffis, R.B. and T.H. Suchanek. 1991. A model of burrow architecture and trophic modes in thalassinidean shrimp (Decapoda: Thalassinidea). Marine Progress Series, 79:171-183. Hart, J.F.L. 1982. Crabs and their Relatives of British Columbia. British Columbia Provincial Museum Handbook 40, 267 pp. Heard, R.W., R.A. King, D.M. Knott, B.P. Thoma, and S. Thornton-DeVictor. 2007. A guide to the Thalassinidea (Crustacea: : Decapoda) of the South Atlantic bight. NOAA Professional Papers National Marine Fisheries Service, 8. Kensley, B. 1996. Systematics and distribution of the Calocarides (Crustacea: Decapoda: Axiidae). Proceedings of the Biological Society of Washington, 109 (1): 53-69. MacGinitie, G.E. and N. MacGinitie. 1968. Natural history of marine . New York: McGraw- Hill. Morris, R.H., D.P. Abbot, and E.C. Haderlie. 1992. Intertidal Invertebrates of California. Stanford University Press, Stanford, CA. 690 pp. Rathbun, M.J. 1902. Descriptions of new decapod from the west coast of North America. Proceedings of the United States National Museum, 24 (1272): 885-905. Rathbun, M.J. 1904. Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10: 1-219. Ricketts, E.F., J. Calvin, J. W. Hedgpeth, and D.W. Phillips. 1985. Between Pacific Tides. Stanford University Press, Stanford, California 5th ed. Sakai, K. 2004. The diphyletic nature of the Infraorder Thalassinidea(Decapoda, ) as derived from the morphology of the gastric mill. Crustaceana 77(9): 1117-1129. Sakai, K. 2006. Upogebiidae of the World (Decapoda, Thalassinidea). Crustaceana Monographs, 6. Williams, A.B. 1986. Mud Shrimps, Upogebia, from the Eastern Pacific (Thalassinoidea: Upogebiidae). San Diego Society of Natural History, Memoir 14. Wicksten, M.K. 2012. Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces. Magnolia Press, Aukland, New Zealand.