Invasion History

First Non-native North American Tidal Record: 1991
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1991

General Invasion History:

The Green Porcelain Crab, Petrolisthes armatus, has a wide range, including the tropical eastern Pacific, from Mexico to Peru, the western Atlantic, from North Carolina to southern Brazil, and the eastern Atlantic, from Senegal to Angola (Haig 1960; Gore and Abele 1976; Rodriguez et al. 2005; Mantelatto et al. 2011). Some differences in life history and morphology have been noted over this range, especially between Atlantic and Pacific crabs (Haig 1960; Gore 1972), suggesting that this species may be a species complex (Rodriguez et al 2005). However, Mantelatto et al. (2011) found no consistent genetic or morphological differences between Atlantic and Pacific populations, or along the western Atlantic from the US to Brazil. Genetic comparisons with African populations have not yet been done. This crab was reported from Pacific Panama by Stimpson in 1859 and described from the Gulf of Mexico in 1850 (Haig 1960). It is uncertain where P. armatus is native. 

North American Invasion History:

Invasion History on the East Coast:

Petrolisthes armatus was first described from Pensacola, Florida on the Gulf Coast (Haig 1960), but was absent from early collections on the Atlantic Coast (e.g. Kingsley 1879). It was first collected on the Atlantic coast of Florida in the 1930s at Miami, in Biscayne Bay (Knott et al. 2000), and became abundant in the Indian River Lagoon in the 1970s (Knott et al. 2000). It was collected from worm reefs near Fort Pierce, and at Hutchinson Island in 1974-1975 (USNM 169902. 169905, US National Museum of Natural history 2011). In the 1980s, this crab was not mentioned in guidebooks covering the East Coast of the southern states (Kaplan 1988; Williams 1984). However, in the 1990s, the range expanded to include St. Catherines Island, Georgia, in 1994, and various sites in South Carolina in 1995. In recent years, it was extremely abundant on the coast of Georgia and South Carolina (Knott et al. 2000; Prezant et al. 2002; Power 2006; Hollebone and Hay 2007 a, b; Tilburg et al. 2010). However, a severe winter cold in 2009-2010 caused a sharp population decline in South Carolina (Canning-Clode et al. 2011). Interannual temperature fluctuations may slow or limit the range expansion of P. armatus. Cold winters are associated with later and reduced larval recruitment (Popp and Wilber 2020).  The northernmost record, to our knowledge, is from Cape Fear Sound, North Carolina (Rodriguez et al. 2005, undated). The rapid range extension of P. armatus' range probably is a response to climate change, and may involve a mixture of natural larval dispersal and anthropogenic transport. Possible human vectors include ballast water, hull fouling, and local oyster transplants. 


Petrolisthes armatus is a porcelain crab (sometimes called a half-crab) with proportionately large claws. The 4th pair of walking legs is vestigial, and the abdomen is more developed than in brachyuran crabs ('true crabs'). In porcelain crabs, the antennae are inserted outside the eyes (not between them, as in brachyuran crabs) (Gosner 1978; Williams 1984). The carapace is roughly circular, and is covered with narrow, low ridges and granules. The front is bluntly triangular, with a depression at the midpoint. The first joint of the antenna has a lobe, usually tipped with a spine. The chelipeds (claws) are long and narrow, about 3-4 X as long as wide, while the carpus (segment next to the claws) is 2 ½ X as long as wide, and bears three spines on its anterior side. The color is variable, often orange-brown to dark brown, or olive green to dark green. The mouthparts (mandible and maxillipeds) are bright blue, a distinctive mark for this species (Mantelatto et al. 2011; Smithsonian Marine Station at Fort Pierce 2011).

The wide geographical range of this species (including both sides of the tropical Atlantic, and the eastern tropical Pacific) and evidence for morphological variability within this range, has raised questions about whether P. armatus is a single species or a species complex. Rodriguez et al. (2005) mentioned unpublished molecular work that suggested that P. armatus consisted of three lineages, warm-temperate Atlantic, Caribbean, and eastern Pacific. Mantelatto et al. (2011) reexamined the phylogeny of P. armatus and its relatives from the western tropical Atlantic and eastern Pacific and concluded that P. armatus was a single species, with no evidence for multiple geographically based lineages. Surprisingly, specimens from Pacific Costa Rica and Ecuador were most similar to those from the Gulf of Mexico (Mantelatto et al. 2011).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Eucarida
Order:   Decapoda
Suborder:   Pleocyemata
Infraorder:   Anomura
Family:   Porcellanidae
Genus:   Petrolisthes
Species:   armatus


Petrolisthes iheringi (Ortmann, 1897)
Petrolisthes leporinus (Smith, 1869)
Petrolisthes similis (Henderson, 1888)
Porcellana armata (Gibbes, 1950)
Porcellana gundelachi (Guerin, 1855)
Porcellana leporina (Heller, 1862)

Potentially Misidentified Species

Petrolisthes galathinuss
Lined porcelain crab, Native to SC-FL coast



Life History- Male and female anomuran crabs press their ventral surfaces together and release eggs and spermatophores simultaneously. The female carries a 'sponge' of eggs brooded between the abdomen and the body (Barnes 1983). Fecundity varied with body size and sampling site, ranging from ~25 to 900 eggs over a range of carapace width of 3-10 mm (Wassick et al. 2018). Fecundity was greater at a northern site (North Inlet SC) in the introduced range than southern introduced sites, or sites in the native range (Wassick et al. 2018). Each egg hatches into a zoea, a larva about 1.6 mm long, armed with a long rostral spine, and two shorter posterior spines, which drifts in the plankton. The zoea goes through a molt into a second zoea stage (2.0 mm long), and then molts into a postlarval megalopa larva, about 1.5 mm long, with prominent eyes and fully developed appendages (Gore 1972). The megalopa molts into a miniature 'first crab' which has all the features of an adult crab, and is capable of crawling on the bottom (Gore 1972; Brossi-Garcia and Moreira 1992). Females have broods fter each molt, on average, every 6 dyas (Popp et al. 2020).Field sampling and modeling suggest that the larvae tend to move toward deeper water during development, leading to upstream transport in the bottom 'salt wedge' of an estuary, and retention of most of the recruits within an estuary (Tilburg et al. 2010).

Ecology- Petrolisthes armatus inhabits intertidal and shallow-water rocky, oyster-reef and mangrove communities. It is a suspension feeder, filtering phytoplankton and detritus form the water column (Hollebone and Hay 2008). This crab was positively associated with rugosity (vertical height and complexity) of oyster reefs (Margiotta et al. 2016). Crabs overwintered in subtidal waters, and low inter temperatures onset of breeding an populaiton growth (Popp etnal. 2020).


Phytoplankton, detritus

Trophic Status:

Suspension Feeder



General HabitatUnstructured BottomNone
General HabitatOyster ReefNone
General HabitatRockyNone
General HabitatMangrovesNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)6Experimental, temperature regime corresponding to 2010 temperature regime near Savannah Georgia, dropping from 14 to 6 C in about 15 days, ~40% survival (Canning-Clode et al. 2011)
Maximum Temperature (ºC)40.5Stillman and Somero 2000, cited by Hollebone and Hay 2007, Pacific crabs.
Minimum Salinity (‰)20Experimental, Crabs from Brazil, nearly half of animals dead or lethargic after 5 days at 13.6 PSU. Some mortality and lethargy was seen at 20 PSU (Shumway 1983).
Minimum Duration12Zoea-Megalopa, 28 C, 34 ppt, animals from Florida (Gore 1972).
Maximum Duration24Zoea-Megalopa, 28 C, 34 ppt, animals from Florida (Gore 1972).
Minimum Width (mm)3For reproductive females, SC (Knott and King undated)
Maximum Width (mm)14Knott and King undated
Broad Temperature RangeNoneWarm temperate-Tropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Petrolisthes armatus has reached extraordinary abundances (up to 20,000-30,000 crabs per m2) in Georgia and South Carolina since its invasion of the southern US Atlantic coast (Knott et al. 2000; Hollebone and Hay 2007a). Experimental and field studies in Georgia have shown a wide range of ecological impacts, including decreasing recruitment of native crabs through competition, suppression of phytoplankton blooms, and promotion of macroalgae abundance, through filter-feeding and altering feeding patterns of predators. High abundances of P. armatus on oyster reefs in Georgia increased recruitment of Oyster Drills (Urosalpinx cinerea), due to switching of predation by mud crabs Panopeus herbstii to P. armatus, decreasing predation on the oyster drills (Hollebone and Hay 2008).

Regional Impacts

CAR-VIICape Hatteras to Mid-East FloridaEcological ImpactCompetition
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus suppressed recruitment of oysters and mud crabs (Panopeus herbstii) (Hollebone and Hay 2008).
CAR-VIICape Hatteras to Mid-East FloridaEcological ImpactFood/Prey
In Georgia estuaries, where Petrolisthes armatus is very abundant, P. armatus was readily consumed by native fishes and the native crabs Callinectes sapidus and Panopeus herbstii in tethering experiments (Hollebone and Hay 2008).
CAR-VIICape Hatteras to Mid-East FloridaEcological ImpactHabitat Change
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus promoted macroalgal growth (Ulva spp.) (Hollebone and Hay 2008).
CAR-VIICape Hatteras to Mid-East FloridaEcological ImpactHerbivory
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus suppressed a phytoplankton bloom, through filter-feeding (Hollebone and Hay 2008).
CAR-VIICape Hatteras to Mid-East FloridaEcological ImpactTrophic Cascade
In oyster reefs in Georgia, high abundances of Petrolisthes armatus increased recruitment of Oyster Drills (Urosalpinx cinerea), due to switching of predation by mud crabs Panopeus herbstii to P. armatus, decreasing predation on the oyster drills (Hollebone and Hay 2008).
S130Ossabaw SoundEcological ImpactCompetition
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus suppressed recruitment of oysters and mud crabs (Panopeus herbstii) (Hollebone and Hay 2008).
S130Ossabaw SoundEcological ImpactFood/Prey
In Georgia estuaries, where Petrolisthes armatus is very abundant, P. armatus was readily consumed by native fishes and the native crabs Callinectes sapidus and Panopeus herbstii in tethering experiments (Hollebone and Hay 2008).
S130Ossabaw SoundEcological ImpactHabitat Change
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus promoted macroalgal growth (Ulva spp.) (Hollebone and Hay 2008).
S130Ossabaw SoundEcological ImpactHerbivory
In mesocosm experiments conducted in Georgia, high abundances of Petrolisthes armatus suppressed a phytoplankton bloom, through filter-feeding (Hollebone and Hay 2008).
S130Ossabaw SoundEcological ImpactTrophic Cascade
In oyster reefs in Georgia, high abundances of Petrolisthes armatus increased recruitment of Oyster Drills (Urosalpinx cinerea), due to switching of predation by mud crabs Panopeus herbstii to P. armatus, decreasing predation on the oyster drills (Hollebone and Hay 2008). High abundances of P. armatus also influenced the effects of mud crabs on Hard Clam (Mercenaria mercenaria behavior. In experiments, the absence of P. armatus, clams reduced their filtering in the presence of mud crabs. When P. armatus, was abundant, clam filtering rates were not reduced. Howver, P. armatus did not significantly affect overall filtering rates, either by their own filtering, or by effects on mud crabs or oysters (Byers et al. 2014).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-VIII None 0 Native Estab
NEP-IX None 0 Native Estab
SEP-H None 1859 Native Estab
CAR-III None 0 Native Estab
SEP-I None 0 Native Estab
SA-II None 0 Native Estab
NEP-VII None 0 Native Estab
WA-I None 0 Native Estab
WA-II None 0 Native Estab
WA-III None 0 Native Estab
WA-IV None 0 Native Estab
NA-ET4 Bermuda 0 Native Estab
SEP-Z None 1932 Crypto Unk
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 1850 Native Estab
CAR-VII Cape Hatteras to Mid-East Florida 1991 Def Estab
CAR-V None 0 Native Estab
CAR-II None 0 Native Estab
CAR-IV None 0 Native Estab
S190 Indian River 1974 Crypto Estab
S180 St. Johns River 2003 Def Estab
S080 Charleston Harbor 1995 Def Estab
SA-IV None 0 Native Estab
S050 Cape Fear River 2005 Def Estab
S200 Biscayne Bay 1935 Crypto Estab
S140 St. Catherines/Sapelo Sounds 1994 Def Estab
S130 Ossabaw Sound 1997 Def Estab
S160 St. Andrew/St. Simons Sounds 2005 Def Estab
S110 Broad River 1991 Def Estab
S120 Savannah River 2003 Def Estab
S076 _CDA_S076 (South Carolina Coastal) 1991 Def Estab
S056 _CDA_S056 (Northeast Cape Fear) 1997 Def Estab
S060 Winyah Bay 1991 Def Estab
S090 Stono/North Edisto Rivers 1997 Def Estab
S100 St. Helena Sound 1997 Def Estab
S206 _CDA_S206 (Vero Beach) 0 Native Estab
G030 North Ten Thousand Islands 0 Native Estab
G045 _CDA_G045 (Big Cypress Swamp) 0 Native Estab
G070 Tampa Bay 0 Native Estab
G090 Apalachee Bay 0 Native Estab
G110 St. Andrew Bay 0 Native Estab
G170 West Mississippi Sound 0 Native Estab
G200 Barataria Bay 0 Native Estab
G180 Breton/Chandeleur Sound 0 Native Estab
G210 Terrebonne/Timbalier Bays 0 Native Estab
G220 Atchafalaya/Vermilion Bays 0 Native Estab
G250 Sabine Lake 0 Native Estab
G300 Aransas Bay 0 Native Estab
G310 Corpus Christi Bay 0 Native Estab
G330 Lower Laguna Madre 0 Native Estab
S170 St. Marys River/Cumberland Sound 2005 Def Estab
SA-III None 0 Native Estab
G130 Pensacola Bay 0 Native Estab
S130 Ossabaw Sound 2010 Def Estab
S183 _CDA_S183 (Daytona-St. Augustine) 2002 Def Estab
PAN_PAC Panama Pacific Coast 1859 Native Estab
PAN_CAR Panama Caribbean Coast 0 Native Estab
SEP-C None 2015 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Abele, Lawrence G.; Kim, Won (1989) The decapod crustaceans of the Panama Canal, Smithsonian Contributions to Zoology 482: 1-50

Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

Blakeslee, April M. H.; Moore, Christopher S.; Stancil, Carter K.; Woodard, Nina C.; Geesin, Megan E.; Manning-Moore, Chloe; Aguilar, Robert;Ogburn, Matthew B.; Smith; Gittman, Scott; Rachel K. (2024) Caribbean Creeping Crabs: northward expansion of the green porcelain crab in North Carolina, USA, Bioinvasions Records 13(1): 109–120 3391/bir.2024.13.1.10

Brossi-Garcia, Ana Luiza, Moreira, Renata Guimarães (1992) Estudos biométricos e morfológicos dos primeiros estágios juvenis de Petrolisthes armatus (Gibbes, 1850) (Decapoda, Porcellanidae) em laboratório, Revista Brasileira de Biologia 56(2): 231-243

Bruce, A. J. (1976) A report on a small collection of shrimps from the Kenya National Marine Parks from at Malindi with notes on selected species, Zoologische Verhandelingen 145(1): 1-72

Byers, James E.; Smith, Rachel S.; Weiskel, Heidi W.; Robertson, Charles Y. (2014) A non-native prey mediates the effects of a shared predator on an ecosystem service, PLOS ONE 9(4): e93969

Canning-Clode, Joao; Fowler, Amy E.; Byers, James E.; Carlton, James T.; Ruiz, Gregory M. (2011) ‘Caribbean creep’ chills out: Vlimate change and marine invasive species, PLOS ONE 6(12): e29657

Eash-Loucks, Wendy E.; Kimball, Mathew E.; Petrinec, Kathryn M. (2014) Long-term changes in an estuarine mud crab community: Evaluating the impact of non-native species, Journal of Crustacean Biology 36(6): 731-738

Florida Museum of Natural History 2009-2013 Invertebrate Zoology Master Database. <missing URL>

Gore, Robert H. (1972) Petrolisthes armatus (Gibbes, 1850): The development under laboratory conditions of larvae from a Pacific specimen (Decapoda, Porcellanidae), Crustaceana 22: 67-83

Gore, Robert H. (1982) Porcellanid crabs from the coasts of Mexico and Central America (Crustacea: Decapoda: Anomura), Smithsonian Contributions to Zoology 363: 1-34

Gore, Robert H.; Abele, Lawrence G. (1976) Shallow water porcelain crabs from the Pacific coast of Panama and adjacent Caribbean waters (Crustacea: Anomura: Porcellanidae), Smithsonian Contributions to Zoology 237: 1-30

Gosner, Kenneth L. (1978) A field guide to the Atlantic seashore., In: (Eds.) . , Boston. Pp. <missing location>

Haig, Janet (1960) The Porcellanidae (Crustacea Anomura) of the eastern Pacific, Allan Hancock Pacific Expeditions 24: 1-400

Hollebone, A. L.; Hay, M. E. (2007a) Population dynamics of the non-native crab Petrolisthes armatus invading the South Atlantic Bight at densities of thousands m–2., Marine Ecology Progress Series 336: 211-223

Hollebone, A. L.; Hay, M. E. (2007b) Propagule pressure of an invasive crab overwhelms native biotic resistance., Marine Ecology Progress Series 342: 191-196

Hollebone, Amanda L.; Hay, Mark E. (2008) An invasive crab alters interaction webs in a marine community., Biological Invasions 10: 347-358

Kaplan, Eugene H. (1988) A Field Gude to Southeastern and Caribbean Seashores, In: (Eds.) . , Boston. Pp. <missing location>

Kingsley, J.S. (1879) On a collection of Crustacea from Virginia, North Carolina, and Florida, with a revision of the genera of Crangonidae and Palaemonidae., Proceedings of the Academy of Natural Sciences of Philadelphia 31: 383-427

Knott, D., Boyko, C., Harvey, A. (2000) Introduction of the green porcelain crab, Petrolisthes armatus (Gibbes, 1850) into the South Atlantic Bight, In: Pederson, Judith(Eds.) Marine Bioinvasions: Proceedings of a conference, January 24-27, 1999.. , Cambridge. Pp. 404

LaJeunesse, Todd C. Parkinson, John Everett Gabrielson, Paul W. Jeong, Hae Jin Reimer, James Davis Voolstra, Christian R. Santos, Scott R. (2019a) Systematic revision of Symbiodiniaceae highlights the antiquity and diversity of coral endosymbionts, Current Biology 28: 2570-2580

Mantelatto, Fernando L.; Pileggi, Leonardo G.; Miranda, Ivana; Wehrtmann, Ingo S. (2011) Does Petrolisthes armatus (Anomura, Porcellanidae) form a species complex or are we dealing with just one widely distributed species?, Zoological Studies 50(3): 372-384

Margiotta, Andrea M.; Shervette, Virginia R.; Hadley, Nancy H.;Plante, Craig J.; Wilber, Dara H. (2016) Species-specific responses of resident crabs to vertical habitat complexity on intertidal oyster reefs, Journal of Experimental Marine Biology and Ecology 477: 7-13

Nizinski, Martha S. (2003) Annotated checklist of decapod crustaceans of Atlantic coastal and continental shelf waters of the United States., Proceedings of the Biological Society of Washington 116(1): 96-157

Oliveira, E., Masunari, S. (1998) Population relationships between the parasite Aporobopyrus curatus (Richardson, 1904) (Isopoda: Bopyridae) and one of its porcelain crab hosts Petrolisthes armatus (Gibbes, 1850) (Decapoda: Porcellanidae) from Farol Island, southern Brazil, Journal of Natural History 32: 1707-1717

Popp, Teresa; Dwilber, ara H. (2021) Associations between winter temperatures and the timing and duration of annual larval recruitment of a non-native anomuran crab, Biological Invasions 44: 1074-1082

Power, Alan; Mitchell, Marcy; Walker, Randal; Posey, Martin; Alphin, Troy; Belcher, Carolyn (2006) <missing title>, University of Georgia Marine Extension Service, Athens. Pp. <missing location>

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

Rodríguez, Irene Teresa; Hernández, Gonzalo; Felder, Darryl L. (2005) Review of the Western Atlantic Porcellanidae (Crustacea: Decapoda: Anomura) with new records, systematic observations, and comments on biogeography., Caribbean Journal of Science 41(3): 544-582

Shumway, Sandra E. (1983) Oxygen consumption and salinity tolerance in four Brazilian crabs, Crustaceana 44(1): 76-82

Smithsonian Marine Station at Fort Pierce 2011 Field Guide to the Indian River Lagoon. <missing URL>

South Carolina Department of Natural Resources (2007) <missing title>, South Carolina Department of Natural Resources, Columbia SC. Pp. 1-95

Stillman, Jonathon H.; Somero, George N. (2000) A comparative analysis of the upper thermal tolerance limits of eastern Pacific porcelain crabs, genus Petrolisthes: influences of latitude, vertical zonation, acclimation, and phylogeny, Physiological and Biochemical Zoology 73(2): 200-208

Tilburg, Charles E.; Seay, Jennie E.; Bishop, T. Dale; Miller, Harlan L. III; Meile, Christof (2010) Distribution and retention of Petrolisthes armatus in a coastal plain estuary: The role of vertical movement in larval transport, Estuarine, Coastal and Shelf Science 88: 260-266

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database.

USGS Nonindigenous Aquatic Species Program 2003-2024 Nonindigenous Aquatic Species Database.

Williams, Austin B. (1984) Shrimps, Lobsters, and Crabs of the Atlantic Coast of the Eastern United States, Maine to Florida, Smithsonian Institution Press, Washington, DC. Pp. <missing location>

Yasser, A. Gh.; Naser, M. D.; ; Abdul-sahib, I. M. (2022) Some new records of marine gastropods from the Iraqi coast, Zoodiversity 56(4): 285-290