Heptacarpus Paludicola Class: Multicrustacea, Malacostraca, Eumalacostraca

Phylum: Arthropoda, Crustacea

Heptacarpus paludicola Class: Multicrustacea, Malacostraca, Eumalacostraca

Order: Eucarida, Decapoda, Pleocyemata, Caridea A broken back shrimp Family: Alpheoidea, Thoridae

Taxonomy: Local Heptacarpus species racic appendages (see chelipeds and pereo- (e.g. H. paludicola and H. sitchensis) were pods) and three pairs of maxillipeds (see briefly considered to be in the genus Spi- mouthparts) (Kuris et al. 2007). The abdo- rontocaris (Rathbun 1904; Schmitt 1921). men and associated appendages are out- However members of Spirontocaris have stretched in Heptacarpus species and the ab- two or more supraorbital spines (rather than domen usually has a sharp bend (“broken- only one in Heptacarpus). Thus a known back shrimp” Kozloff 1993). synonym for H. paludicola is S. paludicola Cephalothorax: (Wicksten 2011). Eyes: Antenna: Antennal scale never much Description longer than rostrum. Antennular peduncle Size: Individuals 20 mm (males) to 32 mm bears spines on each of the three segments (females) in length (Wicksten 2011). Illus- and stylocerite (basal, lateral spine on anten- trated specimen was a 30 mm-long, oviger- nule) does not extend beyond the first seg- ous female collected from the South Slough ment (Wicksten 2011). of Coos Bay. Mouthparts: The mouth of decapod Color: Variable across individuals. Uniform crustaceans comprises six pairs of appendag- with extremities clear and green stripes or es including one pair of mandibles (on either speckles. Color can be deep blue at night side of the mouth), two pairs of maxillae and (Bauer 1981). Adult color patterns arise three pairs of maxillipeds. The maxillae and from chromatophores under the exoskeleton maxillipeds attach posterior to the mouth and and are related to animal age and sex (e.g. extend to cover the mandibles (Ruppert et al. mature and breeding females have promi- 2004). Third maxilliped without expodite and nent color patters) (Bauer 1981). Five with epipods (Fig. 1). Mandible with incisor morphs were described by Bauer (1981) for process (Schmitt 1921). both H. sitchensis and H. paludicola, includ- Carapace: No supraorbital spines ing four color morphs and one transparent (Heptacarpus, Kuris et al. 2007; Wicksten morph. Adults may exhibit camouflaging 2011) and no lateral or dorsal spines. colors based on surrounding algae (Bauer Rostrum: Well-developed, longer than 1981), but color patterns may be more or carapace, extending beyond antennular pe- less fixed (genetically) and variably ex- duncle (Fig. 2). Rostral teeth include both pressed in different environments (Bauer dorsal (6–8, seven in current specimen, Fig. 1982). 1) and ventral (2–4, two in current specimen, General Morphology: The body of decapod Fig. 1). Dorsal edge of rostrum straight, not crustaceans can be divided into the cepha- curved with anterior teeth. lothorax (fused head and thorax) and abdo- Teeth: Rostral teeth present (see Ros- men. They have a large plate-like carapace trum). dorsally, beneath which are five pairs of tho- Pereopods: Pereopods 1–2 with epi-

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. Heptacarpus paludicola. 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.

pods. Epipod morphology is particularly rel- locally, Lysmata californica (Kuris et al. 2007; evant to the genus Heptacarpus and species Wicksten 2011). When following the above with a higher number are considered ances- taxonomy (Christoffersen 1987; Wicksten tral to the group (Bauer 1984b). Pereopods 2011), local members of the Hippolytidae in- 3–5 with bifid dactyls with spines arranged clude Hippolyte californiensis and H. clarki. as follows: merus of pereopod three with Meanwhile, the genus Heptacarpus, with elev- five spines, pereopod four with four spines en local species, falls within the Thoridae, as and pereopod five with 2–4 spines (Wicksten do the local species Lebbeus lagunae and 2011). Second legs chelate, nearly equal, Spirontocaris prionota (Kuris et al. 2007; with seven annulations on carpus (Fig. 1). Wicksten 2011). Chelipeds: Equal, chelate (Fig. 1). Very close in color, morphology, and Abdomen (Pleon): Shrimp-like, with fantail, habitat preference is Heptacarpus sitchensis, body laterally compressed. Side plates of whose adult rostral teeth are 4–8/0–5, but second segment overlap those of first with whose rostrum, while it can reach to the mid- sharp bend (Fig. 1). The third segment with- dle of the antennal scale, does not reach to out hump and the sixth segment is shorter the end of the scale as does that of H. than telson (Fig. 1). Segments 1–3 with paludicola. The rostral teeth are closer pleura that is rounded, fourth segment with together on H. sitchensis and the rostrum is tooth and fifth with spine (Wicksten more slender (Schmitt 1921), as well as being Telson & Uropods: Telson bears 4–5 pairs only equal to or shorter than the carapace. of dorso-lateral spines (Wicksten 2011) (Fig. Our H. sitchensis specimens were only 1.5 1). cm, half the size of the female H. paludicola. Sexual Dimorphism: Females often have Heptacarpus sitchensis is the most commonly broader and larger bodies than males, which found transparent shrimp in tide pools have compressed and squat bodies (Ricketts and Calvin 1971), while H. (Wicksten 2011). paludicola is more common in mudflats and in eelgrass. Possible Misidentifications Heptacarpus taylori, also has a short The family Hippolytidae was split into rostrum, reaching just to the eye and is often three families following a cladistic analysis brightly colored, with a series of teeth from by Christoffersen (1987) that are currently anterior carapace margin to the apex. Hepta- recognized by some (e.g. Wicksten 2011), carpus brevirostris, with smooth rostrum but not all authors (e.g. Kuris et al. 2007). (without lower teeth) that reaches only the first These three families include the Lysmatidae, segment of the antennal peduncle. The mer- Hippolytidae and Thoridae. The Lysmatidae us of H. brevirostris has a single spine on are characterized by very long antennular pereopods 3–4. Heptacarpus palpator is simi- flagella. The three families can further be lar to Heptacarpus brevirostris, but with a distinguised by the number of carpal articles longer rostrum that can be di- or trifid, and a on the second pereopod: 22 or more in Lys- longer antennal scale (Wicksten 1986). matidae, three in Hippolytidae and seven in Heptacarpus stimpsoni, from Puget Sound, Thoridae. In addition, Thoridae and Hip- has rostrum that extends over eye (only polytidae can be differentiated by their su- slightly), with dorsal teeth and pereopod (3–5) praorbital spines, one in the latter and 0–4 in dactyls that are simple and curved. the former family (Wicksten 2011). The Lys- Heptacarpus carinatus is a long-rostrumed matidae is represented by a single species

shrimp, with distal rostral teeth (3–7 dorsal 1979), but are generally only triggered to initi- and 2–6 ventral) and epipods present on ate copulation after physical contact (Bauer pereopods 1–3. Heptacarpus franciscanus, 2011). Little is known about the development from San Francisco Bay, has a rostrum in Heptacarpus species (Strathmann 1987; longer than the carapace. Heptacarpus Puls 2001). pugettensis, H. flexus, and H. tenuissimus Larva: Larval development in Heptacarpus have a hump on the third abdominal seg- species proceeds via a series of zoea, and, a ment. Heptacarpus pugettensis has epipods final, post-zoea (decapodid) stage, each on pereopods 1–2 and a rostrum that just marked by a molt (Puls 2001; Guerao and reaches the end of the first segment of an- Cuesta 2014). The zoea are planktotrophic, tennular peduncle and not beyond. Hepta- have a narrow rostrum (without teeth), cylin- carpus flexus is morphologically similar to H. drical eyestalks, antennule bases that are carinatus, but with epipods on pereopods 1– close together (but not touching), and abdo- 2 only and a narrow rostrum with teeth (4–5 men with postero-lateral spines (Puls 2001; dorsal and 5–8 ventral). Heptacarpus te- see Fig. 48.3, Guerao and Cuesta 2014). nuissimus lacks teeth on the ventrum of the Juvenile: fourth abdominal pleon and also lacks an Longevity: exopod on the third maxilliped (see dichoto- Growth Rate: Growth occurs in conjunction mous key in Wicksten 2011 for Heptacarpus with molting. In pre-molting periods the epi- species). dermis separates from the old cuticle and a dramatic increase in epidermal cell growth oc- Ecological Information curs. Post-molt individuals will have soft Range: Type locality is Humboldt Bay, Cali- shells until a thin membranous layer is depos- fornia. Known range includes Tava Island, ited and the cuticle gradually hardens. During Alaska to San Diego, California (Schmitt a molt decapods have the ability to regener- 1921; Wicksten 2011). ate limbs that were previously autotomized Local Distribution: Coos Bay distribution (Kuris et al. 2007). near, and south of, the Charleston Bridge in Food: Carnivorous (Kozloff 1993). The ma- South Slough. jority of caridean shrimps are omnivorous Habitat: South Slough amongst mud and (Chace and Abbott 1980). eelgrass (Zostera, Ulva), also on pilings, Predators: Fish. floats and in tide pools of outer coasts (Kuris Behavior: Propel themselves backward by et al. 2007; Wicksten 2011). flexing their tails forward and often flip out of a Salinity: Collected at salinity 30. collector’s hand. Members of the genus Hep- Temperature: tacarpus have been shown to exhibit body, gill Tidal Level: Collected at +0.15 m and is in- and embryo grooming in response to microbi- tertidal to 10 m depths (Wicksten 2011). al fouling and parasites. Grooming with spe- Associates: cialized antennal brushes is found in mem- Abundance: Common to abundant (Schmitt bers of the Stenopodidea, Caridea and Den- 1921; Kuris et al. 2007). drobranchiata and suggests a common an- Life-History Information cestor rather than evolutionary convergence Reproduction: Ovigerous female found in (see Bauer 1989). March, in South Slough, Coos Bay. Males Bibliography and females may be (weakly) attracted to each other with sex phermones (Bauer 1. BAUER, R. T. 1979. Sex attraction and

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item/7sk9t2dz. Scripps Institution of Ocean- ography, UC San Diego, San Diego, CA. Updated 2015 T.C. Hiebert