Invasion History

First Non-native North American Tidal Record: 1949
First Non-native West Coast Tidal Record: 1949
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Ampithoe longimana was described from Vineyard Sound, Massachusetts and is native to the East Coast of North America from Veracruz, Mexico to the Bay of Fundy, Canada with an isolated population in the southern Gulf of St. Lawrence (Mills 1964b; Barnard 1965; Bousfield 1973; Winfield et al. 2011). It also occurs in Venezuela, where its invasion status is uncertain (Martin and Diaz 2003). In 1949, it was collected on Catalina Island and in Newport Bay, California (CA) and subsequently found in Morro Bay, CA and Bahía de San Quintín, Baja California both in 1960 (Barnard 1965; Reish and Barnard 1967). However, later collections have not been reported and it was not found in later surveys of Morro Bay (Needles 2007; Needles and Wendt 2013).

North American Invasion History:

Invasion History on the West Coast:

Ampithoe longimana was first collected on the West Coast in 1949 on Santa Catalina Island, California (CA) (USNM 127599, Barnard 1965, US National Museum of Museum of Natural History 2015). In 1951-1954, this amphipod was found in a survey of Newport Bay (Barnard and Reish 1959). It was also collected in 1951 in the Estero de Punta Banda, Baja California (Barnard and Reish 1959) and later in the Bahia de San Quintin in 1960 (Barnard 1965, Carlton 1979, USNM 128304, US National Museum of Museum of Natural History 2015). Possible vectors of introduction include Eastern Oyster transplants, ballast water, or hull fouling.

There are no further records from the West Coast. Needles (2007) and Needles and Wendt (2013) surveyed the fauna of Morro Bay, CA in 2005 and did not find A. longimana. This amphipod could easily be overlooked, so we consider its establishment to be uncertain.


Ampithoe longimana has two medium-large black eyes. The coxal plates are relatively shallow, a little deeper than wide, and the edges of the plates are smooth, lacking setae. Coxal plate 1 is the widest. Antennae 1 and 2 are elongated, especially in the male and are close to body-length. The peduncles of the antenna are long and slender, but less so in the female. The flagellum of antenna 1 is about three times the length of antenna 2. The flagellum of antenna 2 bears bristly whorls of setae.

The gnathopods are somewhat sexually dimorphic in this genus. In males, segments 5 and 6 of gnathopod 1 are about equal and densely covered with setae on their posterior edges. The palm of the gnathopod is short and exceeded by the dactyl. In the female, segments 5 and 6 are shorter, but stouter, while the palm is longer than the dactyl. Gnathopod 2 is smaller in females than males. Further, segment 6 is shorter in females than in males, with a convex palm. Segments 4 and 5 of pereiopods 3 and 4 are roughly equal, with slightly inflated bases. The base of peraeopod 5 is deeper than broad.

In both sexes, the abdominal side plate 3 is broad with the hind corner rounded. Uropod 1 has a slender peduncle and the outer margin has 6 spines, while the outer ramus has 5-6 spines. Uropod 2 has an outer ramus with 3-4 spines. Uropod 3 has a relatively long peduncle, about twice as long as the rami and the outer ramus bears stout hooks. The telson is short, with a rounded apex, with low cusps. Adult males and females are about 10 mm long. Description based on Mills 1964b, Barnard 1965, and Bousfield 1973.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Peracarida
Order:   Amphipoda
Suborder:   Gammaridea
Family:   Ampithoidae
Genus:   Ampithoe
Species:   longimana


Potentially Misidentified Species

Ampithoe lacertosa
NE Pacific native, Alaska to Baja California, with long antennae (Barnard 1965; Chapman 2007).

Ampithoe plumulosa
NE Pacific native, British Columbia to Ecuador, with long antennae; antenna 2 is covered with dense, long setae (Barnard 1965; Chapman 2007).



Ampithoe longimana is a nest-building amphipod occurring in coastal waters and the outer parts of estuaries (Bousfield 1973). Gammarid amphipods have separate sexes, brooded embryos, and direct development. Female A. longimana in New England breed from May to September, with several broods per year (Bousfield 1973).

Ampithoe longimana has a wide native latitudinal range, from the Gulf of St. Lawrence to Florida and Mexico (Bousfield 1973; Winfield et al. 2011). This amphipod is found in polyhaline waters (22-35 PSU), from the lower intertidal to 10 m depth, often in areas of medium current (Bousfield 1973). In Newport Bay, California, it was found 'only in the Upper Bay on coarse shell bottoms or among the roots of eel grass on coarse sand and pulverized shell in the intertidal zone' (Barnard and Reish 1959). This amphipod constructs nests of bits of seaweed glued together with secretions. Bousfield (1973) reported that diatoms were the primary food, but experimental studies show that this amphipod eats a wide range of seaweeds (Duffy and Hay 1991). 



Trophic Status:




General HabitatGrass BedNone
General HabitatUnstructured BottomNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Salinity (‰)22Field data, Bousfield (1973), and reported from upper Polyhaline by Wass (1972)
Maximum Length (mm)10Bousfield 1973
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

The establishment of Ampithoe longimana on the West Coast of North America is uncertain. This species is an important herbivore and prey item for fish in East Coast estuaries, but has had no detectable impacts in California.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NA-S3 None 0 Native Estab
NA-ET2 Bay of Fundy to Cape Cod 0 Native Estab
NA-ET3 Cape Cod to Cape Hatteras 1873 Native Estab
CAR-VII Cape Hatteras to Mid-East Florida 0 Native Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 0 Native Estab
NA-ET4 Bermuda 0 Native Estab
NEP-VI Pt. Conception to Southern Baja California 1949 Def Unk
NEP-V Northern California to Mid Channel Islands 1960 Def Unk
P040 Newport Bay 1951 Def Unk
P058 _CDA_P058 (San Pedro Channel Islands) 1949 Def Unk
P070 Morro Bay 1960 Def Unk
CAR-III None 0 Crypto Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Barnard, J. Laurens (1965) Marine Amphipoda of the family Ampithoidae, Proceedings of the U. S. National Museum 118(3522): 1-46

Barnard, J. Laurens; Reish, Donald J. (1959) Ecology of Amphipoda and Polychaeta of Newport Bay, California, Allen Hancock Foundation Occasional Publications 21: 1-106

Bousfield, E.L. (1973) <missing title>, Comstock Publishing Associates, Ithaca, NY. Pp. <missing location>

Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Chapman, John W. (2007) The Light and Smith Manual: Intertidal invertebrates from Central California to Oregon (4th edition), University of California Press, Berkeley CA. Pp. 545-611

Duffy, J. Emmett; Hay, Mark E. (1991) Food and shelter as determinants of food choice by an herbivorous marine amphipod', Ecology 72(4): 1286-1298

Feeley, James B.; Wass, Marvin L. (1971) The distribution and ecology of the Gammaridea (Crustacea: Amphipoda) of the lower Chesapeake estuaries., Special Papers in Marine Science 2: 1-58

Fox, Richard S.; Bynum, Kenneth H. (1975) The amphipod crustaceans of North Carolina estuarine waters, Chesapeake Science 16(4): 223-237

LeCroy, Sara E. (2002) <missing title>, Florida Department of Environmental Protection, Division of Resource Assessment and Management, <missing place>. Pp. <missing location>

Low-Pfeng, Antonio; Recagno, Edward M. Peters (2012) <missing title>, Geomare, A. C., INESEMARNAT, Mexico. Pp. 236

Martín, A.; Díaz, Y. J. (2003) [The amphipod fauna (Crustacea: Amphipoda) of the coastal waters of eastern Venezuela], Boletin Insititute Espanol de Oceanografia 19(1-4): 327-344

McCarty, Amanda T.; Sotka, Erik E. (2013) Geographic variation in feeding preference of a generalist herbivore: the importance of seaweed chemical defenses, Oecologia 172: 1071-1083

Mills, Eric L. (1964b) Noteworthy amphipods in the collection of the Yale Peabody Museum, Postilla 79: 1-41

Needles, Lisa A. (2007) <missing title>, M.S. Thesis, California Polytechnic State University, San Luis Obispo. Pp. <missing location>

Needles, Lisa A.; Wendt, Dean E. (2013) Big changes to a small bay: Introduced species and long-term compositional shifts to the fouling community of Morro Bay (CA), Biological Invasions 15(6): 1231-1251

Nelson, Walter G. (1995) Amphipod crustaceans of the Indian River Lagoon: current status and threats to biodiversity, Bulletin of Marine Science 57(1): 143-152

Ortíz, Manuel; Martín, Alberto; Díaz, Yusbelly J. (2007) [List and references of crustacean amphipods (Amphipoda: Gammaridea) of the Western Tropical Atlantic], Revista de Biologia Tropical 55(2): 479-498

Prezant, Robert S.; Toll, Ronald B.; Rollins, Harold B.; Chapman, Eric J. (2002) Marine macroinvertebrate diversity of St. Catherines Island, Georgia., American Museum Novitates 3367: 1-31

Reish, Donald J.; Barnard, J. Laurens (1967) The benthic Polychaeta and Amphipoda of Morro Bay, California, Proceedings of the United States National Museum 120(3565): 1-26

Rodríguez-Almaraz, Gabino A.; García-Madrigal, María del Socorro (2014) [Aquatic Invasive Species in Mexico], Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, <missing place>. Pp. 337-371

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database. <missing description>

Wass, Melvin L. (1972) A checklist of the biota of lower Chesapeake Bay, Special Scientific Report, Virginia Institute of Marine Science 65: 1-290

Winfield, Ignacio; Mucino-Reyes, María del Refugio; Ortiza, Manuel; Cházaro-Olveraay, Sergio; Lozano-Aburto, Miguel Ángel (2015) [Biodiversity of benthic amphipods (Peracarida: Amphipoda) associated with algal beds from Puerto Progreso, Yucatán, Mexico], Revista Mexicana de Biodiversidad 86: 613-619

Winfield, Ignacio; Cházaro-Olvera, Sergio; Ortiz, Manuel; Palomo-Aguayo, Ulíses (2011) [Updated checklist of marine invasive species of amphipods (Peracarida: Gammaridea and Corophiidea) from Mexico], Revista de Biologia Marina y Oceanografia 46(3): 349-361

Yale Peabody Museum of Natural History 2008-2016 YPM Invertebrate Zoology - Online Catalog.