Phylum: Arthropoda, Crustacea Class: Malacostraca Heptacarpus sitchensis Order: Decapoda Section: Caridea A broken back shrimp, glass shrimp Family: Thoridae Taxonomy: A re-examination of 263 maxillipeds (see mouthparts) (Kuris et al. preserved specimens revealed that H. pictus, 2007). The abdomen and associated previously considered a different species, is a appendages are outstretched in Heptacarpus junior synonym of H. sitchensis based the species and the abdomen usually has a sharp presence of epipods on the first and second bend (“broken-back shrimp” Kozloff 1993). pereopods and third maxillipeds (Wicksten et Cephalothorax: al. 1996; Wicksten 2011). Local Heptacarpus Eyes: species were also briefly considered to be in Antennae: First segment of the the genus Spirontocaris, however members of antennular peduncle bears spine and the latter genus have two or more supraorbital stylocerite (basal, lateral spine on antennule) spines (rather than only one in Heptacarpus) meets or exceeds the length of the first (Wicksten 2011). Additional synonyms for segment (Wicksten 2011) (Fig. 4). Heptacarpus sitchensis include S. picta, S. Mouthparts: The mouth of decapod sitchensis, and H picta. crustaceans comprises six pairs of appendages including one pair of mandibles Description (on either side of the mouth), two pairs of Size: Individuals 16 mm (males) to 28 mm maxillae and three pairs of maxillipeds. The (females) in length (Wicksten 2011). This maxillae and maxillipeds attach posterior to specimen (from South Slough of Coos Bay) is the mouth and extend to cover the mandibles 15 mm long. (Ruppert et al. 2004). Third maxilliped without Color: Transparent, with orange or brown exopodite and with epipods (Schmitt 1921; lines (longitudinal stripes), green at leg bases Wicksten 2011). and black eyes (Chace and Abbott 1980; Carapace: No supraorbital or other Wicksten 2011). Adult color patterns arise spines (Heptacarpus). from chromatophores under the exoskeleton Rostrum: Well developed and shorter and are related to the age and sex of the than carapace, barely exceeding the length of individual (e.g. mature and breeding females the antennular peduncle (Fig. 4). Rostral have prominent color patterns) (Bauer 1981). teeth are slender and close together (Schmitt Five morphs were described by Bauer (1981) 1921) and include both dorsal (4–8, seven in for both H. sitchensis and H. paludicola, present specimen, Fig. 1) and ventral (0–5, including four color morphs and one three in present specimen, Fig. 1) teeth (Fig. transparent morph. The most extreme 1) (Wicksten 2011). variation in color was seen in H. sitchensis. Teeth: Rostral teeth present (see Adults may exhibit camouflaging colors based Rostrum). on surrounding algae (Bauer 1981), but color Pereopods: Epipods present on patterns may be more or less fixed pereopods 1–2. Epipod morphology is (genetically) and variably expressed in particularly relevant to the genus Heptacarpus different environments (Bauer 1984a). and species with a higher number are General Morphology: The body of decapod considered ancestral to the group (Bauer crustaceans can be divided into the 1984b). Pereopods 3–5 have bifid dactyls cephalothorax (fused head and thorax) and and are thick and bear spines (merus of abdomen. They have a large plate-like pereopod three with 0–9 spines; pereopods carapace dorsally, beneath which are five four and five with 0–5 spines) (Fig. 3) pairs of thoracic appendages (see chelipeds (Wicksten 2011). and pereopods) and three pairs of A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12713 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Heptacarpus sitchensis. 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. Chelipeds: Equal and chelate (Fig. within the Thoridae as do the local species 2). Lebbeus lagunae and Spirontocaris prionota Abdomen (Pleon): Shrimp-like, with fan tail, (Kuris et al. 2007; Wicksten 2011). and laterally compressed body. The side Heptacarpus sitchensis is plates of the second segment overlap those morphologically most similar to the green of the first with sharp bend. The third Zostera dweller H. paludicola, with a segment is without hump and the sixth difference chiefly in the length of the rostrum. segment is shorter than telson (Fig. 1). In H. sitchensis, the rostrum does not reach Pleura of segments 1–3 are rounded and the end of the antennular peduncle, but in H. segments 4–5 bear a postero-lateral tooth paludicola the rostrum reaches and often (Wicksten 2011). extends beyond the antennular peduncle Telson & Uropods: Telson bears 4–5 pairs (Wicksten 2011). Our H. sitchensis of dorso-lateral spines (Wicksten 2011). specimens were only 1.5 cm, half the size of Sexual Dimorphism: Females often have the female H. paludicola. Heptacarpus broader and larger bodies than males, which sitchensis is the most commonly found have compressed and squat bodies transparent shrimp in tide pools (Ricketts and (Wicksten 2011). It is unknown if carapace Calvin 1971), while H. paludicola is more spines are consistently sexually dimorphic, common in mudflats and in eelgrass. but male H. sitchensis appear to differ from Heptacarpus taylori, also has a short females in that they lack a pterygostomian rostrum, reaching just to the eye and is often spine. In fact, this character once defined the brightly colored and with a series of teeth two species H. littoralis (lacking from anterior carapace margin to the apex. pterygostomian spine) and H. sitchensis Heptacarpus brevirostris, with smooth rostrum (bearing pterygostomian spine), until recent (without lower teeth) that reaches only the first evidence revealed that H. littoralis was simply segment of the antennal peduncle. The male H. sitchensis individuals (Stamatious merus of H. brevirostris has a single spine on and Jensen 2004). pereopods 3–4. Heptacarpus palpator, is similar to Heptacarpus brevirostris, but with a Possible Misidentifications longer rostrum that can be di- or trifid, and a The family Hippolytidae was split into three longer antennal scale (Wicksten 1986). families in a cladistic analysis by Heptacarpus stimpsoni, from Puget Sound, Christoffersen (1987) that are currently whose rostrum extends over eye (only recognized by some (Wicksten 2011), but not slightly), with dorsal teeth and pereopod (3–5) all authors (e.g. Kuris et al. 2007). These dactyls that are simple and curved. three families include the Lysmatidae, Heptacarpus carinatus is a long-rostrumed Hippolytidae and Thoridae. The Lysmatidae shrimp, with distal rostral teeth (3–7 dorsal are characterized by very long antennular and 2–6 ventral) and epipods prsent on 1–3 flagella. The three families can further be pereopods. Heptacarpus franciscanus, from divided by the number of carpal articles on San Francisco Bay, has a rostrum longer than the second pereopod: 22 or more in the the carapace. Heptacarpus pugettensis, Lysmatidae, three in Hippolytidae and seven Heptacarpus flexus, and H. tenuissimus have in Thoridae. In addition, Thoridae and a hump on the third abdominal segment. Hippolytidae can be differentiated by their Heptacarpus pugettensis has epipods on supraorbital spines, one in the latter and 0–4 pereopods 1–2 and a rostrum that only just in the former family (Wicksten 2011). The reaches the end of the first segment of Lysmatidae is represented by a single antennular peduncle. Heptacarpus flexus is species locally, Lysmata californica (Kuris et morphologically similar to H. carinatus, but al. 2007; Wicksten 2011). When following the with epipods on pereopods 1–2 only and a above taxonomy (Christoffersen 1987; narrow rostrum with teeth (4–5 dorsal and 5– Wicksten 2011), local members of the 8 ventral). Heptacarpus tenuissimus lacks Hippolytidae include Hippolyte californiensis teeth on the ventrum of the fourth abdominal and H. clarki. Meanwhile, the genus pleon as well as an epipod on the third Heptacarpus, with eleven local species, falls A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12713 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] maxilliped (see dichotomous key in Wicksten epidermis separates from the old cuticle and 2011 for Heptacarpus species). a dramatic increase in epidermal cell growth occurs. Post-molt individuals will have soft Ecological Information shells until a thin membranous layer is Range: Type locality is Sitka, Alaska. Known deposited and the cuticle gradually range includes resurrection Bay, Alaska to hardens. During a molt decapods have the Baja California, Mexico (Wicksten 2011). ability to regenerate limbs that were Local Distribution: Coos Bay distribution previously autotomized (Kuris et al. 2007). near the Charleston Bridge in South Slough. Food: The majority of caridean shrimps are Habitat: Most commonly occurring, omnivorous (Chace and Abbott 1980) and H. transparent shrimp in rock pools (Ricketts and sitchensis individuals have an olfactory Calvin 1971) and also in Zostera beds (South response to food, sensing food in nearby Slough mudflats) and on floats (Kuris et al. water (Bauer 2011). 2007). Predators: Fish and sea spiders, in