Phylum: Arthropoda, Crustacea Crangon franciscorum Class: Multicrustacea, Malacostraca, Eumalacostraca Order: Eucarida, Decapoda, Pleocyemata, Caridea Common gray shrimp Family: Crangonoidea, Crangonidae Taxonomy: Schmitt (1921) described many duncle segment (Wicksten 2011). Inner fla- shrimp in the genus Crago (e.g. Crago fran- gellum of the first antenna is greater than ciscorum) and reserved the genus Crangon twice as long as the outer flagellum (Kuris et for the snapping shrimp (now in the genus al. 2007) (Fig. 2). Alpheus). In 1955–56, the International Mouthparts: The mouth of decapod Commission on Zoological Nomenclature crustaceans comprises six pairs of appendag- formally reserved the genus Crangon for the es including one pair of mandibles (on either sand shrimps only. Recent taxonomic de- side of the mouth), two pairs of maxillae and bate revolves around potential subgeneric three pairs of maxillipeds. The maxillae and designation for C. franciscorum (C. Neocran- maxillipeds attach posterior to the mouth and gon franciscorum, C. franciscorum francis- extend to cover the mandibles (Ruppert et al. corum) (Christoffersen 1988; Kuris and Carl- 2004). Third maxilliped setose and with exo- ton 1977; Butler 1980; Wicksten 2011). pod in C. franciscorum and C. alaskensis (Wicksten 2011). Description Carapace: Thin and smooth, with a Size: Average body length is 49 mm for single medial spine (compare to Lissocrangon males and 68 mm for females (Wicksten with no gastric spines). Also lateral (Schmitt 2011). 1921) (Fig. 1), hepatic, branchiostegal and Color: White, mottled with small black spots, pterygostomian spines (Wicksten 2011). giving gray appearance. Rostrum: Rostrum straight and up- General Morphology: The body of decapod turned (Crangon, Kuris and Carlton 1977). crustaceans can be divided into the cepha- Short, flattened, rounded (Fig. 2) and unorna- lothorax (fused head and thorax) and abdo- mented. Rostrum length reaching or exceed- men. They have a large plate-like carapace ing the cornea of the eye (Wicksten 2011). dorsally, beneath which are five pairs of tho- Teeth: racic appendages (see chelipeds and pere- Pereopods: Inner spine on merus of opods) and three pairs of maxillipeds (see first pereopod, hand of subchela elongate and mouthparts). The body is laterally com- dactyl closes longitudinally (versus obliquely) pressed and shrimp-like in the Caridea. The against inner spine. Second to fifth pereopod abdomen and associated appendages are morphology as follows: second pereopod outstretched and the abdomen usually has a slender and chelate; third slender and with sharp bend (Kuris et al. 2007). simple dactyl; fourth and fifth larger than third Cephalothorax: and bearing setae, also with simple dactyls Eyes: Eyes small, pigmented and not (Wicksten 2011). covered by carapace (Wicksten 2011). Chelipeds: Subchelate. Dactyl almost Antenna: Antennal scale parallel to hand (Plate 319A, Kuris et al. 2007) (scaphocerite) with spine longer than blade (Fig. 3). (Fig. 2). Stylocerite (basal, lateral spine on Abdomen (Pleon): Shrimp-like, with typical antennule) longer than first antennule pe- A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Crangon franciscorum. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. caridean bend, the second segment dominal segment without a pair of dorsal cari- overlaps the first (Fig. 1). Male abdomen nae (keel-like ridges). This genus is monotyp- narrow (see Sexual Dimorphism). Bears ic, the only known member is L. stylirostris rounded pleura and fifth segment with (Kuris and Carlton 1977; Kuris et al. 2007). postero-lateral spine. Morphology of the Crangon species have a straight and sixth abdominal segment is taxonomically upturned rostrum and a telson that is of equal significant—in C. franciscorum, the sixth length or longer than uropods. The genus is segment is slender, with postero-ventral divided into groups (i.e. subgenera, Kuris and spine and ventral groove (Wicksten 2011). Carlton 1977) based on characters of the Telson & Uropods: Telson shorter than sixth abdominal segment. In the first group, uropods. Telson is narrow and with two the sixth abdominal segment is smooth and pairs of lateral spines, acute apex (Wicksten lacks dorsal carinae (instead of two distal cari- 2011). nae). This group is further split based on a Sexual Dimorphism: Females often have sulcate or convex sixth abdominal segment broader and larger bodies than males, which ventrum. The so-called “smooth, sulcate spe- have compressed and squat bodies cies group” (Kuris and Carlton 1977) includes (Wicksten 2011). See also variations in en- all local Crangon species, C. alaskensis, C. dopod morphology (Fig. 4, Siegfried 1989). franciscorum, C. handi, C. nigricauda and C. nigromaculata. Possible Misidentifications Crangon nigricauda, the black tailed The family Crangonidae is character- shrimp, has an antennal blade and spine of ized by first pereopods that are subchelate nearly equal length and cheliped fingers that and second pereopods (if present) that are close almost transversely. Crangon slender and equal in size, each with unseg- nigromaculata has a striking round marking mented carpus. Other characters include on the side of the sixth abdominal segment, chela dactyls that close horizontally across its fingers also close transversely, and its the end of the propodus (“like the blade of a range may not extend north to Oregon. pocket knife” Wicksten 2011), a rostrum that Crangon handi, from the outer coast, has a is small and without spines and a body that very short, stout antennal scale, and a short is squat and somewhat depressed (although sixth abdominal segment (Kuris and Cartlon it can be broad in ovigerous females) 1977). Crangon alaskensis is a small shrimp, (Wicksten 2011). with a slender rostrum, and lacks C. Three crangonid genera were revised franciscorum's very long propodus. Crangon in 1977 by Kuris and Carlton: Lissocrangon, franciscorum can further be differentiated Crangon and Neocrangon. Members of the from C. alaskensis by the chela dactyl that is two former genera are found locally. These almost parallel to the hand (Plate 319A, Kuris genera can be differentiated by carapace et al. 2007) rather than at a 45˚ angle. spination: Lissocrangon lacks gastric Furthermore, C. franciscorum has a spine on spines; Crangon has one median gastric the postero-dorsal corner of the fifth spine; and Neocrangon (Mesocrangon, M. abdominal segment and an inner flagellum of munitella, locally) has two gastric spines. the first antenna that is more than two times Besides lacking gastric spines, Lis- as long as the outer (Plate 316A, Kuris et al. socrangon species have a long, narrow and 2007). Butler calls this species Crangon sharply recurved rostrum, a telson that is franciscorum franciscorum, to distinguish it shorter than the uropods and a sixth ab- from C.f. angustimana Rathbun 1902, the A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] long-clawed Crangon (Butler 1980). This and Pseudomonas sp.). This type of bacterial latter species lives in deeper water, and infection causes the exoskeleton to be within a narrower range of temperatures darkened, cracked and amorphous, with than does C. f. franciscorum (Butler 1980). underlying tissue lesions (Arnold and Hendrickson 1997). Ecological Information Abundance: Common to abundant (Kuris et Range: Type locality is San Francisco Bay, al. 2007). California. Known range includes Resurrec- tion Bay, Alaska to San Diego, California Life-History Information (Schmitt 1921; Wicksten 2011). Reproduction: Many crangonid shrimp spe- Local Distribution: Yaquina Bay; South cies are considered gonochoristic, but evi- Slough (Collver Point, channel) (Krygier and dence suggests that some species exhibit Horton 1975). protandry (Bauer 2004). Identifying ovigerous Habitat: Shallow water in bays and estuar- females is easy as female crangonid shrimp ies with soft substrate. In bay channel with carry eggs, which are attached with between muddy and rocky substrate, also offshore in the joints and rami of the inner pleopods, un- deeper water (Kuris et al. 2007; Wicksten der the abdomen and spawning has been ob- 2011). served almost year-round (Siegfried 1989). Salinity: Euryhaline and collected at 30, Ovigerous females collected from Dec–May, with salinity range from 0.2–34.4 (Krygier June or August and hatching reported from and Horton 1975; Wahle 1985; Wicksten early spring to summer (San Francisco Bay, 2011; Campos et al. 2012). California, Israel 1936; Yaquina Bay, Oregon, Temperature: Great toleration of tempera- Krygier and Horton 1975; Strathmann 1987; ture variation (e.g. 5–25˚C, Campos et al. Campos et al. 2012) during periods or in loca- 2012) prefers warmer water than C. nigri- tions of high salinity (Israel 1936). A spawn- cauda (Krygier and Horton 1975). ing migration was described by Krygier and Tidal Level: Intertidal to 91 m (Schimitt Horton