Invasion History

First Non-native North American Tidal Record: 2000
First Non-native West Coast Tidal Record: 2000
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Caprella simia is native to the Northwest Pacific from Hong Kong to (at least) Pusan, Korea and the Boso Peninsula, east of Tokyo (Mayer 1903; Kim and Lee 1978; Takeuchi et al. 1990). Its range may extend further north, but we have not been able to find many records for this species. In 2000, it was collected in Long Beach Harbor California (Cohen et al. 2002; Ashton personal communication 2007), and individuals have been present in San Francisco Bay since 2007 (Gail Ashton, personal ocmmunication; Foss 2011).

North American Invasion History:

Invasion History on the West Coast:

In 2000, one specimen of Caprella simia was collected in Long Beach Harbor, in a rapid assessment survey of Southern California (Cohen et al. 2002; Cohen et al. 2005). In 2007, Dr. Gail Ashton collected specimens from a single site in San Francisco (Gail Ashton, personal communication). In 2010, C. simia was found to be widespread in San Francisco Bay (Foss 2011). Caprella simia, like other caprellids, is easily transported in ballast water or hull fouling on ships.


Description

Caprellid amphipods have a greatly modified body form, when compared to more familiar gammarid amphipods. The body is elongated (giving rise to the name 'skeleton shrimp'), though the abdomen is compressed. The head is partly fused with the first thoracic segment (called Pereonite 1 in amphipods). The head bears a pair of long antennae 1, somewhat shorter antennae. The 1st antennae (A1) have a 3-segmented peduncle, tipped by a flagellum with multiple segments. The 2nd antennae (A2) may be fringed with long setae, and have 3-4 segments in the peduncle, and a shorter flagellum, usually of 2 segments. A mandibular palp of several segments is present in some genera, arising between the antennae, but this is absent in Caprella. There is a small pair of gnathopods, with small grasping claws with a movable finger (Gnathopod 1) , on Pereonite 1. Pereonite 2 bears a much larger pair of gnathopods (Gnathopod 2), which may have conspicuous spines or setae. Pereonites 3 and 4 usually have round or club-shaped gills, while in most species, including Caprella, pereiopods are absent. Pereiopods 5, 6, and 7 are roughly equal and hook-like, for climbing and attachment, with 6 segments. Females develop oostegites, plates which form a brood pouch. Males are usually larger than females of the same species. Females and immature males can be hard to identify to species level. (Description from: Barnes 1983; Watling and Carlton, in Carlton 2007).  

Adults of Caprella simia range from 6-17 mm in length. Both sexes are distinguished by an elongate body shape and a sharply pointed, forward-pointing dorsal spine on the head. Antenna 1 is 2/3 or more of the body length. Antenna 2 is a little shorter than the peduncle of the Antenna 1. The propodus of Gnathopods 1 have a palm covered with setae, and have grasping spines. Pereonite 2 is the longest segment of the body. Gnathopods 2 are attached near the posterior end of pereonite 2. The propodus of Gnathopod 2 is elongate, with one grasping spine, 2 spinules, a long poison tooth, and a blunt triangular projection. The gills are long and elliptical. Pereopods 5 - 7 have a propodus with grasping spines. Description from: Kim and Lee 1978; Watling and Carlton, in Carlton 2007; Ashton 2012d. The available descriptions refer largely to males. Females are probably smaller, and have less-developed gnathopods.


Taxonomy

Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Peracarida
Order:   Amphipoda
Suborder:   Caprellidea
Infraorder:   Caprellida
Superfamily:   Caprelloidea
Family:   Caprellidae
Genus:   Caprella
Species:   simia

Synonyms

Potentially Misidentified Species

Caprella penantis
Cosmopolitan, a species complex

Caprella scaura
Cosmopolitan, a species complex, introduced to East and West coasts of US

Ecology

General:

Life History - Males and females are morphologically distinct. The males are probably larger, more robust, and armed with larger gnathopods. This is likely an adaptation to competition for females and for guarding themselves during molting, which proceeds mating. The young are brooded by the female in an egg-pouch formed by large plates (oostegites) on the 3rd and 4th pereionites (Turcotte and Sainte Marie 2009). Development is direct, with the newborn juveniles having the general form of the adults.

Ecology - Caprellids can feed in a variety of ways, including filtering small particles from the water, browsing on small filamentous algae, scraping tissue from large algae, scavenging, and predation (Turcotte and Sainte Marie 2009). Caprella simia has been found on seaweeds, and manmade structures such as pilings and floating docks (Takeuchi et al. 1990; Foss 2011). One population in Japan was found associated with a red seaweed (Gelidium amansii), but was most abundant in June-September when the algae was undergoing more rapid growth, and rare during the colder months (Takeuchi et al. 1990). We have not found experimental information on the temperature and salinity tolerances of C. simia.

Food:

Phytoplankton; Detritus

Trophic Status:

Suspension Feeder

SusFed

Habitats

General HabitatMarinas & DocksNone
General HabitatRockyNone
General HabitatGrass BedNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone


Tolerances and Life History Parameters

Maximum Length (mm)22Mayer 1890, cited by Kim and Lee 1978
Broad Temperature RangeNoneWarm temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Caprella simia is common and widespread in Long Beach Harbor and San Francisco Bay. However, no economic or ecological impacts have been reported.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-3a None 0 Native Estab
NWP-2 None 0 Native Estab
NWP-4a None 0 Native Estab
NWP-3b None 0 Native Estab
NEP-VI Pt. Conception to Southern Baja California 2000 Def Estab
P050 San Pedro Bay 2000 Def Estab
NEP-V Northern California to Mid Channel Islands 2010 Def Estab
P090 San Francisco Bay 2010 Def Estab
P065 _CDA_P065 (Santa Barbara Channel) 2011 Def Estab
P062 _CDA_P062 (Calleguas) 2011 Def Estab
P027 _CDA_P027 (Aliso-San Onofre) 2011 Def Estab
P040 Newport Bay 2011 Def Estab
P058 _CDA_P058 (San Pedro Channel Islands) 2011 Def Estab
P030 Mission Bay 2011 Def Estab
P020 San Diego Bay 0 Def Estab
NEP-III Alaskan panhandle to N. of Puget Sound 2008 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
767386 Ruiz et al., 2015 2012 2012-08-15 Tomales- Call Box 401, Bodega Bay, California, USA Def 38.1793 -122.9104
767422 Ruiz et al., 2015 2013 2013-07-19 SeaWorld Marina, Mission Bay, CA, California, USA Def 32.7676 -117.2314
767436 Ruiz et al., 2015 2013 2013-07-23 Marina Village, Mission Bay, CA, California, USA Def 32.7605 -117.2364
767456 Ruiz et al., 2015 2013 2013-07-29 Mission Bay Yacht Club, Mission Bay, CA, California, USA Def 32.7778 -117.2485
767476 Ruiz et al., 2015 2013 2013-08-04 Bahia Resort Marina, Mission Bay, CA, California, USA Def 32.7731 -117.2478
767505 Ruiz et al., 2015 2013 2013-08-01 Hyatt Resort Marina, Mission Bay, CA, California, USA Def 32.7634 -117.2397
767523 Ruiz et al., 2015 2013 2013-08-03 Mission Bay Sport Center, Mission Bay, CA, California, USA Def 32.7857 -117.2495
767551 Ruiz et al., 2015 2013 2013-08-02 The Dana Marina, Mission Bay, CA, California, USA Def 32.7671 -117.2363
767564 Ruiz et al., 2015 2013 2013-08-05 Paradise Point Resort, Mission Bay, CA, California, USA Def 32.7730 -117.2406
767578 Ruiz et al., 2015 2013 2013-08-30 201 Main, Morro Bay, CA, California, USA Def 35.3564 -120.8474
767591 Ruiz et al., 2015 2013 2013-08-27 City Harbor, Morro Bay, CA, California, USA Def 35.3709 -120.8582
767603 Ruiz et al., 2015 2013 2013-09-05 Launch Ramp, Morro Bay, CA, California, USA Def 35.3577 -120.8508
767612 Ruiz et al., 2015 2013 2013-08-29 Moorings, Morro Bay, CA, California, USA Def 35.3619 -120.8548
767625 Ruiz et al., 2015 2013 2013-08-31 Morro Bay Marina, Morro Bay, CA, California, USA Def 35.3641 -120.8532
767632 Ruiz et al., 2015 2013 2013-08-28 Sealion Dock, Morro Bay, CA, California, USA Def 35.3658 -120.8555
767655 Ruiz et al., 2015 2013 2013-09-04 Tidelands, Morro Bay, CA, California, USA Def 35.3602 -120.8521
767665 Ruiz et al., 2015 2013 2013-07-16 Naval Base Point Loma, San Diego Bay, CA, California, USA Def 32.6886 -117.2343
767676 Ruiz et al., 2015 2013 2013-07-17 Naval Station San Diego, San Diego Bay, CA, California, USA Def 32.6867 -117.1333
767705 Ruiz et al., 2015 2013 2013-07-25 Navy Ammo Dock, Pier Bravo, San Diego Bay, CA, California, USA Def 32.6939 -117.2276
767759 Ruiz et al., 2015 2013 2013-07-26 Pier 32 Marina, San Diego Bay, CA, California, USA Def 32.6516 -117.1077
767783 Ruiz et al., 2015 2013 2013-07-28 Marriott Marquis and Marina, San Diego Bay, CA, California, USA Def 32.7059 -117.1655
767820 Ruiz et al., 2015 2011 2011-09-20 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8067 -122.4432
767832 Ruiz et al., 2015 2011 2011-09-14 Coyote Point Marina, San Francisco Bay, CA, California, USA Def 37.5880 -122.3160
767853 Ruiz et al., 2015 2011 2011-09-13 Oyster Point Marina, San Francisco Bay, CA, California, USA Def 37.6725 -122.3864
767888 Ruiz et al., 2015 2011 2012-09-19 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8609 -122.4853
767903 Ruiz et al., 2015 2011 2011-09-21 South Beach Harbor, San Francisco Bay, CA, California, USA Def 37.7797 -122.3871
767915 Ruiz et al., 2015 2011 2011-09-20 Jack London Square Marina, San Francisco Bay, CA, California, USA Def 37.7947 -122.2822
767949 Ruiz et al., 2015 2011 2011-09-12 Paradise Cay Yacht Harbor, San Francisco Bay, CA, California, USA Def 37.9156 -122.4769
767964 Ruiz et al., 2015 2011 2011-09-12 Corinthian Yacht Club, San Francisco Bay, CA, California, USA Def 37.8103 -122.3228
767978 Ruiz et al., 2015 2012 2012-08-24 Richmond Marina Bay Yacht Harbor, San Francisco Bay, CA, California, USA Def 37.9134 -122.3523
768002 Ruiz et al., 2015 2012 2012-08-23 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8609 -122.4853
768018 Ruiz et al., 2015 2012 2012-08-28 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8071 -122.4341
768033 Ruiz et al., 2015 2012 2012-08-27 Port of San Francisco Pier 31, San Francisco Bay, CA, California, USA Def 37.8078 -122.4060
768055 Ruiz et al., 2015 2012 2012-09-11 Ballena Isle Marina, San Francisco Bay, CA, California, USA Def 37.7676 -122.2869
768077 Ruiz et al., 2015 2012 2012-08-30 Oyster Point Marina, San Francisco Bay, CA, California, USA Def 37.6633 -122.3817
768101 Ruiz et al., 2015 2012 2012-08-29 Coyote Point Marina, San Francisco Bay, CA, California, USA Def 37.5877 -122.3174
768148 Ruiz et al., 2015 2012 2012-09-06 Loch Lomond Marina, San Francisco Bay, CA, California, USA Def 37.9736 -122.4802
768166 Ruiz et al., 2015 2012 2012-09-05 Port of Oakland, San Francisco Bay, CA, California, USA Def 37.7987 -122.3228
768189 Ruiz et al., 2015 2012 2012-09-07 Jack London Square Marina, San Francisco Bay, CA, California, USA Def 37.7940 -122.2787
768245 Ruiz et al., 2015 2012 2012-09-12 Emeryville, San Francisco Bay, CA, California, USA Def 37.8396 -122.3133
768268 Ruiz et al., 2015 2013 2013-08-15 Ballena Isle Marina, San Francisco Bay, CA, California, USA Def 37.7656 -122.2858
768291 Ruiz et al., 2015 2013 2013-08-20 Coyote Point Marina, San Francisco Bay, CA, California, USA Def 37.5877 -122.3163
768311 Ruiz et al., 2015 2013 2013-08-22 Jack London Square Marina, San Francisco Bay, CA, California, USA Def 37.7926 -122.2746
768350 Ruiz et al., 2015 2013 2013-08-13 Oyster Point Marina, San Francisco Bay, CA, California, USA Def 37.6639 -122.3821
768394 Ruiz et al., 2015 2013 2013-08-19 Richmond Marina Bay Yacht Harbor, San Francisco Bay, CA, California, USA Def 37.9138 -122.3522
768414 Ruiz et al., 2015 2013 2013-08-12 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8078 -122.4354
768446 Ruiz et al., 2015 2013 2013-08-16 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8611 -122.4851

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Takeuchi, Ichiro; Yamakawa, Hiroshi; Fujiwara, Masamu (1990) Density fluctuations of caprellid amphipods (Crustacea) inhabiting the red alga Gelidium amansii (Lamouroux) Lamouroux with emphasis on Caprella okadai, La Mer 28(1): 30-36

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