FAMILY ALPHEIDAE Rafinesque, 1815 Snapping shrimp

Geographic Range Most snapping shrimp are much more diverse in tropical areas than in temperate seas. An exception is the diversity of species of Betaeus, the visored shrimp. These shrimp live in the northern Gulf of California and from northwestern Baja California as far north as Alaska.

Description The snapping shrimp, family Alpheidae, remind many viewers of small lobsters. At least one of the first pereopods is heavily chelate. The carpus of the second pereopod is divided into articles. The eyes may be exposed or covered by the front of the carapace. Most snapping shrimp hide in burrows, tubes or cracks by day and are active at night. Rostrum, if present, unarmed. Eyes usually covered by carapace. Mandibles with incisor process and palp of two segments. First pair of pereopods often with one chela. or both chelae powerfully developed. Second pair of pereopods minutely chelate, long,slender, equal, with carpus segmented. Telson usually broad, rounded. Rostrum not present; front not spined, either emarginate between eyes or evenly rounded. Chelae usually similar, inverted so that dactyli are on the lower side. Carpus of second pereopod with five segments. Sixth abdominal somite with movable plate articulated at posteroventral angle. Telson broad. Outer margin of outer uropod, or exopod, with two distal spines, outer immovable, inner movable, and normally long and robust. Exopod on third maxilliped. Epipods on at least first two pereopods. One Genus, Betaeus, is found along the BC coast. Two local species, B. harrimani and B. setosus, are termed “hooded shrimps,” because of the forward projection of the carapace to shade the eyes. Both species apparently are very secretive and diffilcult to detect in the intertidal zone, if the paucity of preserved specimens is a valid criterion. Their larvae are distinguished from those of other British Columbia caridean shrimps by the fifth pereopod, which develops early, is much longer than other pereopods, and bears an elongated apical spine.

References Butler, T.H. 1980. Shrimps of the Pacific coast of Canada. Ottawa; Department of Fisheries and Oceans Canada. Wicksten, M.K. 2012. Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces. Magnolia Press, Aukland, New Zealand.

GENUS BETAEUS Betaeus harrimani Betaeus setosus BETAEUS HARRIMANI Rathbun, 1904 Northern Hooded Shrimp

Geographic Range Sitka, Alaska to Newport Harbor, California. Type locality Sitka, Alaska.

Habitat Intertidal, in pools, among oysters, in burrows of Upogebia pugettensis and Neotrypaea californiensis

Morphology Body deep, somewhat compressed. Shell thin, mainly smooth. scattered minute setae. Rostrum absent. Eye round, stout stalk with sharp spine on inner margin. Antennae: stylocerite reaching almost to end of second segment of antennular peduncle; scaphocerite broad, spine exceeding blade, reaching past middle of last segment of antennular peduncle. Carapace: slightly curved and depressed anterior; anterior margin with 2 shallow sinuses. Pereopods: P1 with fingers 0.5 x to as long as palm, with or without gape; P2 slender, with 5 carpal articles, first article equal in length to next 3 together; P3 slender, somewhat flattened, with thin, curved dactyls; P5 similar to 3-4 but with bands of setae forming brush on distal half of propodus. Abdomen: pleura of A1-3 rounded, pleura of 4 and 5 angled rather than rounded Telson: with 2 pair spines on dorsal surface, 2 spines at each posterolateral angle; posterior margin deeply curved.

Distinctions Separated from B. setosus, which also has chelae inverted with dactyli on the lower side, and anterior dorsal margin of carapace projected to shade the eyes, by having dactyli of P3-5 slender and simple; chela of P1 with fingers not longer than rest of propodus, chela of this pereopod about third to half as wide as long.

Size Males: total about 35 mm; females: total about 33 mm

Coloration Living animal transparent, except for chromatophores in distinct pattern. Color consists of small red chromatophores usually surrounded by dark blue spots. Pigmented areas of carapace are 2 broad bands on the dorsal part separated by thin middorsal line, unpigmented except between eyes. Two colored patches on the carapace at base of antennae. In female, green eggs in ovary may show through shell. Abdomen also pigmented dorsally and middorsally but deeply colored in band posteriorly at joints. Lateral part of A6 often pigmented as is telson, which, however, has light streak. Uropods mainly red but setae creamy white. Fine band of color near anterior dorsal margin of first somite. Eyestalk, antennule, and antenna heavily pigmented, with flagella reddish. M3 has scattered spots. Cheliped (PI) well colored, mainly red, but tips of chelae clear.All pereopods except P1 have scattered branching chromatophores. Color ends in straight line midlaterally and ventral parts are quite transparent. By day, when red chromatophores expanded, shrimp is reddish or purplish; by night is distinctly blue. One specimen, after preservation, turned uniform pale green Color determined by distribution of blue and red chromatophores: translucent, reddish to purplish, pale green; turning blue at night. Remarks This species is partly free living under logs, boulders, shells, in tide pools; and partly commensal in the burrows of the mud shrimp, Upogebia pugettensis, and the ghost shrimp, Neotrypaea californiensis. All known occurrences in the province are from Vancouver Island shores. The question of whether it is really rare or rarely found remains unanswered. It may be that the shrimp eludes collectors because it is very agile, inclined to remain motionless for a while, and then to move very quickly; and even in clear water, its protective coloration and transparency makes the shrimp difficult to see.

References original description: Rathbun, M.J., 1904. Decapod crustaceans of the Northwest coast of North America.— Harriman Alaska Expedition 10: 1-210, Plates 1-10. Butler, T.H. 1980. Shrimps of the Pacific coast of Canada. Ottawa; Department of Fisheries and Oceans Canada. Hart, J.F.L. 1964. Shrimps of the genus Betaeus on the Pacific coast of North America with descriptions of three new species. Proceedings of the United States National Museum115: 431-466. Wicksten, M.K. 2012. Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces. Magnolia Press, Aukland, New Zealand. BETAEUS SETOSUS Hart, 1964 Fuzzy Hooded Shrimp

Geographic Range Hecate Strait, B.C., to Morrow Bay, CA It is presumed that B. setosus was first collected in Canadian waters in Esperanza Inlet, on High Island, and off Tatchu Point, June 28, 1934

Habitat Among rocks, kelp holdfasts, tide pools, on pilings, and among roots of eelgrass Zostera marina, intertidal to 18 m. In Puget Sound, B. setosus is invariably associated with the anomuran crab Pachycheles rudis, both of which often are found in dead shells of giant barnacles Balanus nubilis.

Morphology Body deep, little compressed, setose. Shell thin, mainly smooth, scattered short setae on carapace Rostrum absent. Eye large, round, sharp spine on stout stalk. Antennae: peduncle long, second segment flattened; stylocerite long, acute tip, extending past middle of second segment; inner flagellum, about as long as carapace, outer half as long, setiferous; scale longer than telson, narrow, large spine longer than lamina, separated from lamina for almost half its length; basicerite with upper lateral lobe, lower with strong spine; peduncle long; flagellum twice carapace length, flattened proximally. Third maxilliped long, stout; proximal segment broad, flattened proximally, twisted; penultimate segment about half length of distal, latter setiferous; has exopod; has epipod. Carapace: dorsal frontal margin deeply indented medially, slightly depressed, produced laterally to form “blister” over each eye; lateral frontal margin curved smoothly; posterolateral margin distinctly notched adjacent to cardiac region. Pereopods: P1 less than twice carapace length, very stout, both sides similar in shape, and subequal in size, merus shorter than chela, stout, triangular, epipod present; P2 about 3/4 length of P1, slender, chelate with epipod; P3 longer than P2, with epipod; P4 slightly shorter than P3, as stout, with epipod; P5 shorter than P4, more slender, dactylus moderately stout. Abdomen: posteroventral margins of A4 and A5 angled rather than rounded, latter with blunt spine; A6 with triangular articulated plate adjacent to base of uropod Telson: longer than A6, broad, tapering to broadly rounded tip with 2 pairs dorsal spines, and 2 pairs at each posterolateral angle; distal angle of outer margin of proximal part of outer uropod with sharp spine, adjacent to stout, movable spine; uropods about equal, both longer than telson. Male Similar to female except abdomen narrower; chelipeds larger in proportion, chelae longer than carapace; and antennular peduncle proportionately longer.

Distinctions Distinguished from the northern hooded shrimp by having the dactyli of P3-5 moderately stout, and tips bifid; the chela of P1 with fingers longer than rest of propodus; chela of this pereopod more than half as wide as long; median dorsal frontal margin of carapace deeply notched.

Size Males: total about 20 mm; females: total about 25 mm.

Coloration Living specimens in British Columbia a uniform white or yellow in the light but pink or orange in the dark. Color change due to presence of tiny red chromatophores, which expand in dark, thickly dotted over dorsal half of shrimp (except over eyes) and on chelae. Some specimens have pale blue tinge on chelae and flagella. Cast shell pale blue dorsally, with yellow setae on lamina of antennal scale, and on tail fan. Tips of dactyli of pereopods yellow Remarks In British Columbia, this shrimp has been caught in a trawl at 18 m, in tide pools, and with the anomuran crab, Pachycheles rudis, Stimpson, 1859, in cavities under the holdfasts of kelp, usually Pterygophora californica or eelgrass roots [i]Phyllospadix[/i], and often in pairs. Elsewhere in its range, and at times listed as the southern species B. harfordi. B. setosushas been found under rocks, among marine plants, and on pilings. Ovigerous females (smallest, 4.8 mm carapace length) occurred on the west coast of Vancouver Island, May to August, and in California, February to June. B. setosus has not been found in the Strait of Georgia, or in other inside coastal waters.

References original description: Hart, J.F.L., 1964. Shrimps of the genus Betaeus on the Pacific Coast of North America with descriptions of three new species. Proceedings of the United States National Museum 115: 431-466. Butler, T.H. 1980. Shrimps of the Pacific coast of Canada. Ottawa; Department of Fisheries and Oceans Canada. Hart, J.F.L. 1964. Shrimps of the genus Betaeus on the Pacific coast of North America with descriptions of three new species. Proceedings of the United States National Museum115: 431-466. Wicksten, M.K. 2012. Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces. Magnolia Press, Aukland, New Zealand.