Caprella Drepanochir Class: Malacostraca Order: Amphipoda, Caprellidea a Skeleton Shrimp, Or Caprellid Amphipod Family: Caprellidae

Phylum: Arthropoda, Crustacea Caprella drepanochir Class: Malacostraca Order: Amphipoda, Caprellidea A skeleton shrimp, or caprellid amphipod Family: Caprellidae Taxonomy: The Caprellidae are a very rather than laterally compressed (compare to distinctive family of amphipods. They were gammarid amphipods, e.g. Eogammarus previously a separate amphipod suborder, but confervicolus) (Kozloff 1993; Watling and were recently found to be polyphyletic, arising Carlton 2007). at least twice from different gammarid Cephalon: Round cephalon with no dorsal amphipod lineages (Laubitz 1993; Takeychi spines or tubercles (Fig. 1) (Laubitz 1976), 1993; Watling and Carlton 2007). Current however body spination is a highly variable research places them as highly modified trait among individuals (Watling and Carlton members of the suborder Corophiidea (Myers 2007). Head partially fused with the first and Lowry 2003; Watling and Carlton 2007), a pereonite (segment of pereon) and the first taxon divided into two infraorders (Caprellida, pair of gnathopods (Fig. 1). Pereonite one not Corophiida) each with different evolutionary more than twice as long as head in male feeding strategies and associated morphology (Laubitz 1970) and shorter in female (Laubitz (Myers and Lowry 2003). 1970) (Fig. 2). Rostrum: Cephalon without rostrum Descripton (Laubitz 1976). Size: The illustrated specimens (from Coos Eyes: Small (Laubitz 1976) (Fig. 1). Bay) include a 13 mm long male (Fig. 1) and Antenna 1: Less than half total body an 8 mm long female (Fig. 2) (Measured from length (Laubitz 1970). In males, the first anterior (head) to posterior (abdomen), antenna is approximately equal to the Laubitz 1970). Males collected in Japan were cephalon combined with pereonite two 13 mm (Arimoto et al. 1976; Utinomi 1943) (Laubitz 1970) (Fig. 1). Articles 2–3 of while those from Alaska were 12.4 mm in peduncle are setose while the flagellum is length (Laubitz 1970). shorter than peduncular articles one and two, Color: White, with brown chromatophores. and bears 13 articles (Laubitz 1970) (Fig. 1). The illustrated female is darker than the male In the illustrated female, antenna one is a little specimen. longer than cephalon and pereonite one and General Morphology: The body of the flagellum has 10 articles (Fig. 2). amphipod crustaceans can be divided into Antenna 2: Antenna two in the three major regions. The cephalon (head) or illustrated specimens is longer than the cephalothorax includes antennules, antennae, peduncle of antenna one and has flagellum mandibles, maxillae and maxillipeds with short setae (Laubitz 1970) (Figs. 1, 2). (collectively the mouthparts). Posterior to Mouthparts: Mandible with molar the cephalon is the pereon (thorax) with (McCain 1975) and without palp (McCain seven pairs of pereopods attached to 1975). Left ‘lacinia mobilis' with five teeth (Fig. pereonites followed by the pleon (abdomen) 5) and right ‘lacinia mobilis' denticulate but not with six pairs of pleopods. The first three sets five-toothed (McCain 1975) (not figured). of pleopods are generally used for swimming, Pereon: Pereon with only six segments (not while the last three are simpler and surround seven as in other amphipods) and no the telson at the animal posterior. Caprellid pereopods on pereonites three or four amphipods differ from the rest of amphipoda (Caprellidae, McCain 1975; Laubitz 1976). in that the abdomen is greatly reduced, Pereonites cylindrical and longer than deep especially the last three abdominal segments (Laubitz 1976). Pereonites in this species are (urosome) and associated appendages without dorsal spines or tubercules, but are (uropods). Their body is also elongated covered with fine hairs (Fig. 1). Male Hiebert, T.C. 2015. Caprella drepanochir. 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. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12700 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] pereonite one is not more than twice the grasping spines (Fig. 1c). Female pereopods length of the head while female pereonite one more slender than those of males (Laubitz is shorter than the head (Laubitz 1970) (Fig. 1970) (Fig. 2). 2). Gills on pereonites three and four only. Pleon: The pleon or seventh pereonite is Round in shape and fleshy (Caprella, Mayer reduced and often unsegmented in caprellids 1890; Watling and Carlton 2007) (Figs.1, 2). (McCain 1975). Female individuals with one Gills in male individuals are more circular and pair of lobes, but no single-articled females are broadly rounded (Watling and appendages above these lobes (Figs. 2, 4) Carlton 2007). Oostegites (marsupium) (Caprella, McCain 1975). present on pereonites 3–4 in females only. Pleonites: The marsupium consists of two pairs of Urosomites: foliaceous plates called oostegites Epimera: (Caprellidae, Laubitz 1976) that grow from gill Telson: bases (Fig. 2) (Arimoto et al. 1976; Watling Sexual Dimorphism: Males much larger and and Carlton 2007). more elongate than females, with a longer Coxae: first pereonite and an exaggerated second Gnathopod 1: Male gnathopod one is gnathopod. Females when brooding have small and the propodus and dactyl have conspicuous oostegites (see pereon) and serrate grasping margins (Fig. 1) while the lack mandible palps (Watling and Carlton female gnathopod is small, setose (Fig. 2). 2007). Gnathopod 2: Male gnathopod two is very large, especially the propodus, width Possible Misidentifications being less than half overall length. The In contrast to the more familiar gnathopod is setose, except the dactyl and Gammaroidea, the bodies of caprellid distal part of propodus (Laubitz 1970). The amphipods are elongate and cylindrical, their basis is small, with no lateral spines at the pereonites are very long and their three pairs base (Figs. 1, 1b). The propodus is of pereopods are prehensile. Caprellids have tuberculate anterodistally and palm is with 2–3 pairs of gills on the middle pereonites and small proximal grasping-spine, large distal lack the abdominal pleopods of gammarid poison spine, large triangular projection distal amphipods. Members of three subfamilies to poison spine and separated by cleft. (family Caprellidae) occur locally including, There are no anterodorsal projections on Caprellinae, Paracercopinae and Phtisicinae. propodus in this species (Laubitz 1970) (Fig. The caprellid family Cyamidae are parasitic 1). The dactyl is heavy, slightly curved, with on cetacean mammals. They are very short inner margin slightly denticulate and not bodied, dorso-ventrally flattened (like setose. The gnathopod is attached just isopods), and have third and fourth pereonites posterior to middle of pereonite two (in male) especially adapted for hanging on to their and attached near the middle of pereonite host. two, but not at its anterior end (in female) Phtisicinae have three pairs of gills, not (Laubitz 1970) (Fig. 2). The palm of propodus two (unlike Caprellinae). In addition, they has a proximal grasping spine and an have no molar surface on the mandible. The accessory spine, and a minute distal poison Phtisicinae have rudimentary pereopods on spine (Fig. 3). Ventral spines between pereonites three and four (Laubitz 1970). Of insertions of second gnathopods are lacking this family, Perotripus brevis has been in this species (Fig. 1a). Female gnathopods reported from California (McCain 1975; are much smaller than those of males. Watling and Carlton 2007). It, as well as Pereopods 3 through 7: Pereopods Cercops compactus (Laubitz, 1970), occurs in 5–7 prehensile (for grasping) and increase in Puget Sound. Caprella compactus has also size posteriorly (Fig. 1). Propodus on all been reported from the outer coast of Oregon, pereopods rather stout, with a concave inner at Cape Arago (Laubitz 1970; Martin 1977) edge and a proximal tooth with a pair of and is in the only representative of the Hiebert, T.C. 2015. Caprella drepanochir. 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. subfamily Paracercopinae locally. Cercops have only a uni-articulate flagellum (McCain compactus does not have an elongate body 1975). as other caprellids do, its abdomen has five A few caprellids have a ventral spine segments, and pereonites five and six are between the insertions of the second short and stout (Watling and Carlton 2007). gnathopods (C. drepanochir does not): C. The subfamily Caprellinae is the most californica, C. equilibra, C. mendax, and C. speciose with 23 species in the genus pilidigitata (Laubitz 1970). Caprella Caprella, three in Tritella and one each in californica has a long, forward directed Deutella and Mayerella (Watling and Carlton cephalic spine (Laubitz 1970). Both the 2007). propodus and basis of the male gnathopod Tritella pereopods have only one article two are very long in this species. Caprella and their second antennae have swimming californica has a wide distribution from the setae (Laubitz 1970; McCain 1975). Three western to eastern Pacific coasts (Martin species are found in Oregon: T. laevis is 1977). Caprella equilibra has no cephalic strongly stenohaline, and

Load more