Phylum: Arthropoda, Crustacea Traskorchestia traskiana Class: Multicrustacea, Malacostraca, Eumalacostraca A beach hopper Order: Peracarida, Amphipoda, Senticaudata, Talitrida, Talitridira Family: Talitroidea, Talitridae Taxonomy: The genus Traskorchestia was beaches, particularly at night (Bousfield designated in 1982 by Bousfield based on 2007). Traskorchestia species are character- taxonomic characters and individuals collect- ized by smooth unmodified bodies, lateral ed from field expeditions in 1955 from Alas- eyes and their small to medium size (for key ka to Baja, California (for characters see see Bousfield 1982). Figs. 1–3, 5, Bousfield 1982). Many Cephalon: Traskorchestia species, including T. traski- Rostrum: Rostrum simple (Fig. 1). ana (e.g. O. traskiana) were previously Eyes: Eyes large and oval in shape members of Orchestia (Bousfield 1982; (Fig. 1). Bousfield 2007). Antenna 1: Very short, consisting of five articles (Fig. 1) (Stebbing 1906). Description Antenna 2: Short, peduncle not thick- Size: The illustrated individual (from South ened, flagellum with 16 articles (16 in males, Slough of Coos Bay) is 20 mm in length. 12 in females) (Stebbing 1906). Both first and Individuals can be 13 mm or a little more second antennae are less massive than the (Barnard 1975). beach hoppers found on the more open coast Color: Pale brown, orange antennae. Over- (e.g. M. pugettensis Ricketts and Calvin all body color dull green or gray-brown with 1971). slightly blue legs (see Plate 19, Kozloff Mouthparts: Mandible without palp 1993) (Ricketts and Calvin 1971). (Fig. 2) (Talitridae) and maxilliped with four General Morphology: The body of amphi- articles, although the fourth is not well pod crustaceans can be divided into three developed (Fig. 4) (Barnard 1954). major regions. The cephalon (head) or Pereon: cephalothorax includes antennules, anten- Coxae: The plate of coxa one is about nae, mandibles, maxillae and maxillipeds half as long as coxa two (Fig. 1). (collectively the mouthparts). Posterior to Gnathopod 1: Dactyl of gnathopod the cephalon is the pereon (thorax) with one is slender and subchelate, especially in seven pairs of pereopods attached to pere- mature males, although not as simple as in onites followed by the pleon (abdomen) with Megalorchestia (see M. pugettensis). Trans- six pairs of pleopods. The first three sets of lucent process on article four (Fig. 5). pleopods are generally used for swimming, Gnathopod 2: Smooth convex palm while the last three are simpler and surround with no spine at hinge of articles six and sev- the telson at the animal posterior. Talitrid en (Fig. 6). amphipods are in the suborder Gammar- Pereopods 3 through 7: Pereopod idea, one of the largest groups of amphipods seven longer than six (Barnard 1975). in marine and estuarine habitats. They have Pleon: Pleopods strong, biramous with the smooth bodies that are only slightly com- first three about equal in size and branches pressed, are commonly called beach hop- with 7–10 segments (not figured) (Barnard pers and can be highly abundant on coastal 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. Traskorchestia traskiana. 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, Charles- ton, OR. 1975). Traskorchestia species are larger than Pleonites: Pleonites five and six not Megalorchestia and found on exposed beach- fused (Fig. 1) (Barnard 1975). es. Traskorchestia georgiana is up to 13.5 Urosomites: The third uropod is uni- mm in length and is found with T. traskiana in ramous (Talitridae, Barnard 1954) with the drift line on rocky beaches and amongst ramus shorter than peduncle and narrowing seagrass and algal debris. Traskorchestia distally (Barnard 1975) (Fig. 3). georgiana has weak pleopods with 4–6 seg- Epimera: ments on the rami and its first gnathopod Telson: Telson puffy, split (not visible in lat- lacks the process on the fourth article (male) eral view) and with several spines (Fig. 3) that is found on T. traskiana (Bousfield 1982). (Barnard 1975). Transorchestia enigmatica is another Sexual Dimorphism: Males generally larger local talitrid amphipod species that is up to 15 than females and with larger gnathopods. mm in length. It was introduced in solid bal- Populations in Washington state were domi- last from the southern hemisphere and is now nated by females (63% compared to 37% found in Lake Merritt near San Francisco Bay, male, Koch 1990). California (Bousfield and Carlton 1967). It is a member of the T. chiliensis species group, an Possible Misidentifications introduced species found under debris on The Talitridae are a family of gam- sandy beaches. Transorchestia chiliensis has marid amphipods called beach hoppers and a long, inflated second antenna and the sec- are ubiquitous in damp sands, where they ond gnathopod has a sinuous dactyl and a live within clumps of seaweed. They survive triangular tooth near the hinge. well in air. Talitridae are characterized by a single branched third uropod (Figs. 1, 4 Ecological Information Megalorchestia pugettensis) and a mandible Range: Type locality is in California without a palp (Fig. 2). Nine local talitrid (Bousfield 1982). Known range includes species are currently reported (Bousfield Aleutian Islands in Alaska to Washington 2007) including six Megalorchestia, two state and south to Magdalena Bay, Baja Cali- Traskorchestia and one Transorchestia fornia (Barnard 1954; Koch 1989b). species. Some authors differentiate Local Distribution: Locally present at several Megalorchestia species as sand hoppers locations in Coos Bay, at North Bay and Cape (intertidal on sandy beaches), while Arago (Barnard 1954). Traskorchestia species as beach fleas Habitat: Rocky and/or sandy beaches with (intertidal in coastal leaf-litter) (Bousfield algae, salt marshes (under debris and boards) 1982; Pelletier et al. 2011). (Barnard 1975). Also occurs under driftwood The genus Megalorchestia are found on high protected beaches and inner on exposed beaches and are usually larger Salicornia marshes (e.g. Metcalf Preserve) than Traskorchestia. Species in the latter (Kozloff 1993). Beach fleas (Traskorchestia genus have subchelate first gnathopods, not species) are differentiated from sand hoppers simple ones, and slender first gnathopod (Megalorchestia species) in that the former dactyls, not heavy ones. The seventh group tend not to modify their habitat pereopods are also longer than the sixth, substrate (Bousfield 1982). while the reverse is true in Megalorchestia. Salinity: Euryhaline. Salinity tolerance rang- The third uropods narrows and branches in es from brackish slough (Ricketts and Calvin Traskorchestia, but is not broad. 1971) to high beaches of salty bays (Kozloff 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] 1993) and the outer coast (Barnard 1954). hundreds under debris. Individuals can reach The majority of individuals tested (95%) sur- densities of 55 individuals per gram of dry vived for 24 hours in salinities ranging from wrack (Koch 1989b). 2.5 to 50 (Koch 1991). Life-History Information Temperature: Up to 30–38˚C (Morritt and Reproduction: Most amphipods have sepa- Spicer 1998). rate sexes with some sex determination corre- Tidal Level: Usually along the wrack line, lated with environmental conditions (Straude but also found more than 20 meters above 1987). Females brood embryos in an external tidewater (Ricketts and Calvin 1971). A su- thoracic brood chamber and irrigate embryos pralittoral species that can withstand desic- with a flow of water produced by pleopod cation of up to 25% of body water loss movement. Development within this brood (Morritt and Spicer 1998), although desicca- chamber is direct and individuals hatch as ju- tion resistance decreases in smaller individ- veniles that resemble small adults, with no uals (Koch 1989b). Individuals prefer not to larval stage. Little is known about the repro- be inundated with water and will migrate up- duction and development in T. traskiana, but shore with an incoming tide (Koch 1989a). some ovigerous females were observed in Associates: In Metcalf Preserve, associates March in Coos Bay and reported during spring include other amphipods, sphaeromid iso- and summer in northern populations, where pods and the gastropod, Ovatella. Talitrid females produce two broods per year (e.g. amphipods are known to host rhabditid nem- Alaska, Koch 1990). Breeding occurred in atodes under their dorsal pereonites (e.g. February in Washington state and continued Megalorchestia californiana and M. cornicu- through spring (see Fig. 1, Koch 1990) and lata, Rigby 1996) as well as within the in- brood sizes ranged between six and 16 indivi- tersegmental spaces in T. traskiana duals per brood (Koch 1990). (Adamson and Rigby 1996). Talitrid amphi- Larva: Since most amphipods are direct de- pods also host and transport mites of Uropo- veloping, they lack a definite larval stage. In- dina, Dermanyssina and Acaridida (Pugh et stead, this