Invasion History

First Non-native North American Tidal Record: 1872
First Non-native West Coast Tidal Record: 1985
First Non-native East/Gulf Coast Tidal Record: 1872

General Invasion History:

Microdeutopus gryllotalpa is native to the Eastern Atlantic, where it occurs from the Western Baltic and southern Norway to Atlantic Spain and the Mediterranean Sea (Myer 1969; Lincoln 1979; Bellan-Santini et al. 1993). It occurs from the intertidal zone to 155 m, and often occurs in moderately brackish lagoons at salinities as low as 15 PSU (Bousfield 1973). Based on its limited range and association with manmade structures and eutrophic habitats, it appears to have been introduced to the Northwest Atlantic, from Casco Bay, Maine to Chesapeake Bay (Verrill and Smith 1873; Bousfield 1973; Chapman 2000; Wells et al. 2014; Ruiz et al., unpublished data). In the Pacific, it has been found in Humboldt Bay, California since the 1980s (Boyd et al. 2002).

North American Invasion History:

Invasion History on the West Coast:

Microdeutopus gryllotalpa is introduced on the West Coast, where it is currently only known from Humboldt Bay, California (1st collected in the 1980s - Boyd et al. 2002; Chapman 2007). It is known from sloughs and saltmarshes at the northern and southern ends of the Bay (Boyd et al. 2002).

Invasion History on the East Coast:

On the East Coast, M. gryllotalpa was first reported in Vineyard Sound, Massachusetts by Verrill and Smith (1872, as M. minax) where it ‘sometimes occurs in great abundance on eelgrass in brackish ponds' (Verrill and Smith 1872). It has been reported from Massachusetts Bay (MIT Sea Grant 2003) to the Indian River estuary, Delaware, south of Delaware Bay (Watling and Maurer 1972). It was not reported in earlier surveys of amphipods in Chesapeake Bay (Cowles 1930; Feeley and Wass 1971; Marsh 1972; Wass 1972), but was found in fouling plates in lower Chesapeake Bay in 1994 (Ruiz et al., unpublished data). John Chapman (Chapman 2000; personal communication 2008) and James Carlton (personal communication 2008) consider this species introduced in the Northwest Atlantic, based on its limited range on the East Coast, compared to its much wider European range, its absence from high latitudes, its potential for transport on ship hulls, and its preference for nutrient-rich, disturbed environments (Bousfield 1973). Potentially, it could have been a much earlier introduction to North America, but we have insufficient records to document early spread along the East Coast.


Microdeutopus gryllotalpa has a somewhat slender and shallow body. In the male, Coxa Plate 1 is produced anteriorly into a point, which ends behind and below the antennal sinus. In both sexes, Coxa Plate 5 has two lobes and the anterior one projects slightly deeper. Antenna 1 is about half the body length and has a flagellum of up to 22 segments, with a minute accessory flagellum. Antenna 2 has a flagellum of 6-9 segments, shorter than peduncle segment 5.

The gnathopods are sexually dimorphic in this family. Gnathopod 1 is greatly enlarged in males and much larger than Gnathopod 2. Segment 2 of Gnathopod 1 is expanded distally, while segment 5 (carpus, 'hand') is greatly expanded in the male, and is about as long as deep, with 2-4 teeth on the posterior distal margin. The propodus (segment 6) is short, with a sinuous posterior edge. The dactyl (segment 7), when folded, reaches the angle of the palm of the carpus. In the male, Gnathopod 2 has its basis (segment 2) greatly expanded, with the anterior margin convex. In both sexes, segments 5 and 6 are elongated. In the female, Gnathopods 1 and 2 are roughly equal in length. In the female's Gnathopod 1, the propodite is longer than the carpus. In females, the carpus is only moderately expanded. 

The rami of Uropod 3 are about equal in length to the peduncle. The outer rami are slightly longer; and the apices have groups of 3 spines across tips, with paired and solitary spines on margins. The terminal setae on the telson are long. Males reach 8 mm and females reach 10 mm in size. The color is greenish-white with small brown patches on the dorsal surface. Description based on: Myers 1969, Bousfield 1973, Lincoln 1979, and Bellan-Santini et al. 1993.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Peracarida
Order:   Amphipoda
Suborder:   Gammaridea
Family:   Aoridae
Genus:   Microdeutopus
Species:   gryllotalpa


Autonoe grandimana (Bruzelius, 1859)
Microdeutopus minax (Smith, 1874)
Microdeutopus bidens (Sowinski, 1880)

Potentially Misidentified Species

Microdeutopus anomalus
This amphipod is native to both sides of the North Atlantic from Norway to the Canary Islands and Mediterranean Sea; and Cape Ann, Massachusetts to mid-Atlantic states and Bermuda, in marine habitats (Bousfield 1973).



Microdeutopus gryllotalpa is a tube-dwelling amphipod, living in vegetation and fouling communities in estuaries in coastal waters (Bousfield 1973; Lincoln 1979). Gammarid amphipods have separate sexes, brooded embryos, and direct development.  Females in a population near Cadiz, Spain matured at 3.5-4.5 mm (Drake and Arias 1995). In M. gryllotalpa, mating takes place in the female's tube (Borowsky 1989). Females in a Greek lagoon carried 1-8 eggs in a brood, and young were born at ~1 mm length (Karakiri and Nicolaidu 1987). Breeding was year-round in Spanish and Greek populations (minimum temperature 8C) (Karakiri and Nicolaidu 1987; Drake and Arias 1995), but is likely to be seasonal in regions with colder winters.

Microdeutopus gryllotalpa tolerates a wide range of temperature (-1.8 to 27C) and salinity (15-65 PSU) (Bousfield 1973; Karakiri and Nicolaidu 1987; Drake and Arias 1995). This amphipod occurs from the intertidal zone to 150 m depth (Bousfield 1973; Lincoln 1979). The U-shaped tubes, constructed from bits of debris, glued with secretions from the animal's glands, provide some protection from desiccation in the intertidal zone, and probably from predators (Borowsky 1989). Habitats include rocky areas, algae, seagrasses (Zostera and Ruppia), oyster and mussel beds, salt marshes and fouling communities on docks and floats (Bousfield 1973; Lincoln 1979; Boyd et al. 2002). Microdeutopus gryllotalpa feeds on macroalgae, especially filamentous green algae (e.g. Cladophora and Ulva sp.), detritus, and to lesser extent on seagrasses (Zostera sp.) (Hauxwell et al. 1998; Jephson et al. 2008).


Phytoplankton, detritus

Trophic Status:

Suspension Feeder



General HabitatGrass BedNone
General HabitatCoarse Woody DebrisNone
General HabitatSalt-brackish marshNone
General HabitatUnstructured BottomNone
General HabitatOyster ReefNone
General HabitatMarinas & DocksNone
Salinity RangeMesohaline5-18 PSU
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Salinity RangeHyperhaline40+ PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)-1.8Based on geographical range and personal observations (Paul Fofonoff, Narragansett Bay and Rhode Island salt ponds, with winter ice cover)
Maximum Temperature (ºC)27Field, Mazama Lagoon, Greece (Karakiri and Nicolaidu 1987)
Minimum Salinity (‰)15Bousfield 1973
Maximum Salinity (‰)65Field, San Francisco de Asis lagoon, Cadiz, Spain (Drake and Arias 1995).
Minimum Length (mm)3.5Females start breeding at 3.5 mm in summer, 4.5 mm in winter, near Cadiz, Spain (Drake and Arias 1995).
Maximum Length (mm)10Females (Males reach 8 mm, Bousfield 1973)
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNoneMesohaline-Euhaline

General Impacts

Microdeutopus gryllotalpa is an abundant amphipod in algae and seagrass communities on the coast of the Northeast US (Bousfield 1973). It has potential impacts on Eelgrass (Zostera marina) and Widgeongrass (Ruppia maritima) by covering the leaves with its tubes, but also consuming epiphytic algae (Bousfield 1973; Jephson et al. 2008). This amphipod is also a likely food for fishes.

Ecological Impacts

Herbivory- Microdeutopus gryllotalpa is the most abundant grazer of macroalgae in Waquoit Bay, Massachusetts, making up an average of over 50% of the grazer community. In experiments, it was capable of grazing at 5X the growth rate of algae in low-nutrient conditions, but at only 1/10 of the growth rate under high nutrient conditions (Hauxwell et al. 1998).

Regional Impacts

NA-ET3Cape Cod to Cape HatterasEcological ImpactHerbivory
Microdeutopus gryllotalpa is the most abundant grazer of macroalgae in Waquoit Bay, Massachusetts, making up on average over 50% of the grazer community. In experiments, it was capable of grazing at 5X the growth rate of algae in low-nutrient conditions, but at only 1/10 of the growth rate under high nutrient conditions (Hauxwell et al. 1998).
N195_CDA_N195 (Cape Cod)Ecological ImpactHerbivory
Microdeutopus gryllotalpa is the most abundant grazer of macroalgae in Waquoit Bay, Massachusetts, making up on average over 50% of the grazer community. In experiments, it was capable of grazing at 5X the growth rate of algae in low-nutrient conditions, but at only 1/10 of the growth rate under high nutrient conditions (Hauxwell et al. 1998).
MAMassachusettsEcological ImpactHerbivory
Microdeutopus gryllotalpa is the most abundant grazer of macroalgae in Waquoit Bay, Massachusetts, making up on average over 50% of the grazer community. In experiments, it was capable of grazing at 5X the growth rate of algae in low-nutrient conditions, but at only 1/10 of the growth rate under high nutrient conditions (Hauxwell et al. 1998).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
N170 Massachusetts Bay 2000 Def Estab
M130 Chesapeake Bay 1994 Def Estab
M100 Delaware Inland Bays 1972 Def Estab
N195 _CDA_N195 (Cape Cod) 1872 Def Estab
M090 Delaware Bay 1972 Def Estab
P130 Humboldt Bay 1985 Def Estab
M070 Barnegat Bay 1968 Def Estab
M040 Long Island Sound 1905 Def Estab
M020 Narragansett Bay 2000 Def Estab
M010 Buzzards Bay 1910 Def Estab
N180 Cape Cod Bay 1905 Def Estab
MED-IX None 0 Native Estab
MED-VI None 0 Native Estab
NA-ET3 Cape Cod to Cape Hatteras 1872 Def Estab
NEP-IV Puget Sound to Northern California 1985 Def Estab
B-III None 0 Native Estab
NA-ET2 Bay of Fundy to Cape Cod 1879 Def Estab
B-I None 0 Native Estab
MED-IV None 0 Native Estab
MED-VII None 0 Native Estab
MED-III None 1853 Native Estab
NEA-II None 0 Native Estab
NEA-V None 0 Native Estab
N100 Casco Bay 2013 Def Estab
N130 Great Bay 2013 Def Estab
B-IV None 0 Native Estab
NEA-IV None 0 Native Estab
MED-II None 0 Native Estab
AR-V None 0 Native Estab
NEA-III None 0 Native Estab
B-II None 0 Native Estab
MED-V None 0 Native Estab
NEP-V Northern California to Mid Channel Islands 2006 Def Estab
P070 Morro Bay 2006 Def Estab
N170 Massachusetts Bay 2001 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Amaral, Maria José; Costa, Maria Helena (1999) Macrobenthic communities of saltpans from the Sado estuary (Portugal), Acta Oecologia 20(4): 27?332

Apadoo, Chandani; Myers, Alan A. (2004) Corophiidea (Crustacea: Amphipoda) from Mauritius, Records of the Australian Museum 56: 331-362.

Bakir, Ahmet Kerem; Katagan, Tuncer (2014) Distribution of littoral benthic amphipods off the Levantine coast of Turkey with new records, Turkish Journal of Zoology 38: 23-34

Bell, Richard; Buchsbaum, Robert; Chandler, Mark (2005) Inventory of intertidal marine habitats, Boston Harbor Islands National Park area, Northeastern Naturalist 12(Special Issue 3): 169-200

Bellan-Santini, Denise; Karaman, Gordon; Krapp-Schickel, Gertraud; Ledoyer, Michel; Myers, Alan A.; Ruffo, Sandro; Schiecke, Ulrich (1982) The Amphipoda of the Mediterranean: Part 1. Gammaridea (Acanthonotozomatidae to Gammaridae), Memoires de l'Institut Oceanographique (Monaco) 13: 1-364

Bellan-Santini, Denise; Karaman, Gordon; Krapp-Schickel, Gertraud; Ledoyer, Michel; Myers, Alan A.; Ruffo, Sandro; Schiecke, Ulrich (1993) The Amphipoda of the Mediterranean: Part 3. Gammaridea: Melphippidae to Talitridae; Ingolfiellidea; Caprellidea, Memoires de l'Institut Oceanographique (Monaco) 13: 577-813

Borowsky, Betty (1989) The effects of residental tubes on reproductive behaviors in Microdeutopus gryllotalpa (Crustacea: Amphipoda), Journal of Experimental Marine Biology and Ecology 128: 1170125

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

Boyd, Milton J.; Mulligan, Tim J; Shaughnessy, Frank J. (2002) <missing title>, California Department of Fish and Game, Sacramento. Pp. 1-118

Cacabelos, Eva; Lourido, Antía; Troncoso, Jesús S. (2010) Composition and distribution of subtidal and intertidal crustacean assemblages in soft-bottoms of the Ria de Vigo (NW Spain), Scientia Marina 74(3): 455-464

Chapman, John W. (2000) Climate effects on the geography of nonindigenous peracaridan crustacean introductions in estuaries., In: Pederson, Judith(Eds.) Marine Bioinvasions. , Cambridge MA. Pp. 66-80

Chapman, John W. 2005 Aoridae. <missing URL>

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

Christodoulou, Magdalini; Paraskevopoulou, Sofia; Syranidou, Evdokia; Koukouras, Athanasios (2013) The amphipod (Crustacea: Peracarida) fauna of the Aegean Sea, and comparison with those of the neighbouring seas, Journal of the Marine Biological Association of the United Kingdom 93(5): 1303-1327

Cowles, R.P. (1930) A biological study of the offshore waters of Chesapeake Bay, United States Bureau of Fisheries Bulletin 46: 277-381

Drake, P.; Arias, A. M. (1995) Distribution and production of Microdeutopus gryllotalpa (Amphipoda: Aoridae) in a shallow coastal lagoon in the bay of Cadiz, Spain, Journal of Crustacean Biology 15(3): 454-465

Eddy,Elizabeth N. ; Roman, Charles T. (2016) Relationship between epibenthic invertebrate species assemblages and environmental variables in Boston Harbor’s intertidal habitat, Northeastern Naturalist 23(1): 45-66

Evagelopoulos, A.; , Spyrakos, E.; Koutsoubas, D. (2006) The biological system of the lower salinity ponds in Kalloni Saltworks (NE. Aegean Sea, Greece): phytoplankton and macrobenthic invertebrates., Transitional Waters Bulletin 3: 23-25

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

Graening, G. O.; Rogers, D. Christopher; Holsinger, John R.; Barr, Cheryl; Bottorff, Richard (2012) Checklist of inland aquatic Amphipoda (Crustacea: Malacostraca) of California, Zootaxa 3544: 1-27

Hauxwell, Jennifer; McClelland, James; Behr, Peter J.; Valiela, Ivan (1998) Relative importance of grazing and nutrient controls of macroalgal biomass in three temperate shallow estuaries., Estuaries 21(2): 347-360

Hauxwell, Jennifer; Osenberg, Craig W.; Frazer, Thomas K. (2004) Conflicting management goals: manatees amd invasive competitors inhabit restoration of a native macrophyte., Ecological Applications 14(2): 571-586

Holmes, S. J. (1905) The Amphipoda of southern New England., Bulletin of the Bureau of Fisheries 24: 457-541

Jephson, Therese; Nyström, Per; Moksnes, Per-Olav; Baden, Susanne P. (2008) Trophic interactions in Zostera marina beds along the Swedish coast, Marine Ecology Progress Series 369: 63-76

Karakiri, Maria; Nicolaidu, Artemis (1987) Population studies on the Amphipoda of Mazoma lagoon (Greece), Helgolander Meeresuntersuchungen 41: 453-454

King, R.; Myers, A. A. 2015 North-eastern Atlantic Amphipoda: Aoridae: <em>Microdeutopus gryllotalpa</em> Costa, 1853. <missing URL>

Larsen, Peter F. (1985) The benthic fauna associated with the oyster reefs of the James River estuary, Virginia, U. S. A., Internationale Revue der Gesamten Hydrobiologie 70(9): 707-814

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Loveland, Robert E.; Shafto, Sylvia S. (1984) Fouling Organisms, In: Kennish, Michael J., and Lutz, Richard A.(Eds.) Ecology of Barnegat Bay, New Jersey.. , Berlin. Pp. 226-20

Mancinelli, Giorgio; Sabetta, Letizia Alberto Basset brackish coastal lake located in Puglia (SE Italy) on the Adriatic Sea. (2007) Colonization of ephemeral detrital patches by vagile macroinvertebrates in a brackish lake: a body size-related process?, Oecologia 151: 292-302

Marsh, G. Alex (1973) The Zostera epifaunal community in the York River, Virginia, Chesapeake Science 14(2): 87-97

MIT Sea Grant 2003-2008 Introduced and cryptogenic species of the North Atlantic. <missing URL>

Myers, A. A. (1969) A revision of the amphipod genus Microdeutopus Costa (Gammaroidea: Aoridae), Bulletin of the British Museum (Natural History) Zoology 17: 93-148

Pederson, Judith, and 13 authors (2021) 2019 Rapid Assessment Survey of marine bioinvasions of southern New England and New York, USA, with an overview of new records and range expansions, Bioinvasions Records 10(2): 22-–237

Prato, E.; Biandolino, F. (2005) Amphipod biodiversity of shallow water in the Taranto seas (north-western Ionian Sea), Journal of the Marine Biological Association 85: 333-338

Procaccini, Gabrielle; Scipione, Maria Beatrice (1993) Observations on the spatial-temporal distributions of crustacean amphipods in the Fusaro coastal lagoon (Central Tyrhennian Sea, Italy), and some notes on their presence in Mediterranean lagoons, Marine Ecology 13(3): 203-224

Sezgün, Murat; Kocata, Ahmet; Kataúan, Tuncer (2001) Amphipod fauna of the Turkish central Black Sea region, Turkish Journal of Zoology 25: 57-61

Sumner, Francis B., Osburn, Raymond C., Davis, Bradley M. (1913a) A biological survey of the waters of Woods Hole and vicinity. Part I. Section I. Physical and Zoological. Section II. Botanical, Bulletin of the Bureau of Fisheries 31: 1-544

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Vader, Wim; Christophersen, Carlos G.; Kempe, Jochen; Skadsheim, Arfinn (1984) Gammarus inequicauda Stock 1966, in Norway (Crustacea: Amphipoda), Fauna Norvegica Series A 5(5): 9-12

Verrill, A.E.; Smith, S.I. (1873) <missing title>, 1 Report of the United States Commission of Fish and Fisheries, <missing place>. Pp. 1-757

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

Watling, Les; Maurer, Don (1972) Marine shallow water amphipods of the Delaware Bay area, U.S.A., Crustaceana <missing volume>: 251-266

Wells, Christopher D. and 23 authors (2014) Report on the 2013 rapid assessment survey of marine species at New England bays and harbors, Massachusetts Office of Coastal Zone Management, Boston MA. Pp. 32