Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
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Class Malacostraca - Malacostracans

Phylum Arthropoda - Arthropods
Subphylum Crustacea - Crustaceans
Class Malacostraca - Malacostracans

Superorder Eucarida - Eucarida (Crabs, Crayfish, Shrimp, etc.)
Order Decapoda - Crabs, Crayfishes, Lobsters, Prawns, and Shrimp
Infraorder Anomura - Hermit Crabs and Mole Crabs
Superfamily Galatheoidea
Family Munididae - Squat Lobsters
Genus Pleuroncodes
Species planipes - Red Crab
Family Porcellanidae - Porcelain Crabs
Genus Euceramus
Species praelongus - Euceramus praelongus
Genus Petrolisthes
Species eriomerus - Petrolisthes eriomerus
Species armatus - Green Porcelain Crab
Genus Polyonyx
Species gibbesi - Polyonyx gibbesi
Genus Pachycheles
Species rudis - Pachycheles rudis
Superfamily Hippoidea
Family Hippidae - Mole Crabs
Genus Emerita
Species talpoida - Atlantic Mole Crab
Species analoga - Pacific Mole Crab
Superfamily Paguroidea - Hermit Crabs
Family Lithodidae
Genus Paralithodes
Species rathbuni - Spiny King Crab
Genus Cryptolithodes
Species sitchensis - Cryptolithodes sitchensis
Family Diogenidae
Genus Clibanarius
Species vittatus - Thinstripe Hermit Crab
Genus Petrochirus
Species diogenes - Petrochirus diogenes
Family Paguridae
Genus Pagurus
Species acadianus - Pagurus acadianus
Species annulipes - Pagurus annulipes
Species grainosinanus - Grainyhand Hermit Crab
Species hirsutiusculus - Hairy Hermit Crab
Species longicarpus - Long-Clawed Hermit Crab
Species pollicaris - Flat-clawed Hermit Crab
Species samuelis - Blueband Hermit Crab
Family Coenobitidae
Genus Coenobita
Species clypeatus - Caribbean hermit crab
Infraorder Astacidea - Crayfishes and Lobsters
Family Nephropidae
Genus Homarus
Species americanus - American Lobster
Superfamily Astacoidea - Crayfish
Family Astacidae
Genus Pacifastacus
Species leniusculus - Signal Crayfish
Species gambelli - Pacifastacus gambelli
Family Cambaridae
Genus Cambarus
No Taxon Subgenus Cambarus
No Taxon bartonii complex
Species bartonii - Cambarus bartonii
Subspecies bartonii - Cambarus bartonii bartonii
No Taxon Subgenus Hiaticambarus
Species speciosus - Beautiful Crayfish
No Taxon Subgenus Jugicambarus
Species dubius - Cambarus dubius
Species asperimanus - Cambarus asperimanus
Species tartarus - Oklahoma cave crayfish
No Taxon Subgenus Lacunicambarus
Species diogenes - Devil Crayfish
No Taxon Subgenus Puncticambarus
Species robustus - Robust Crayfish
No Taxon Subgenus Tubericambarus
Species polychromatus - Cambarus polychromatus
Genus Orconectes
No Taxon Subgenus Trisellescens
Species immunis - Calico Crayfish
Species validus - Powerful Crayfish
No Taxon Subgenus Cockerinus
Species propinquus - Northern Clearwater Crayfish
Species erichsonianus - Reticulate Crayfish
No Taxon Subgenus Gremicambarus
Species virilis - Virile Crayfish
No Taxon Subgenus Faxonius
Species limosus - Spiny-Cheek Crayfish
Species obscurus - Allegheny Crayfish
No Taxon Subgenus Procericambarus
Species rusticus - Rusty Crayfish
No Taxon Subgenus Orconectes
Species maletae - Orconectes maletae
Genus Procambarus
No Taxon Subgenus Leconticambarus
Species alleni - Florida Crayfish
No Taxon Subgenus Ortmannicus
Species acutus - White River Crayfish
Subspecies acutus - White River Crayfish
Species fallax - Slough Crayfish
No Taxon Subgenus Scapulicambarus
Species clarkii - Red Swamp Crayfish
Genus Faxonius
Species palmeri - Faxonius palmeri
Species luteus - Faxonius luteus
Infraorder Axiidea
Family Callianassidae - Ghost Shrimp
Genus Neotrypaea
Infraorder Brachyura - True Crabs
Family Calappidae - Box crabs
Genus Calappa
Species flammea - Flame-streaked Box Crab
Family Cancridae - Rock Crabs
Genus Metacarcinus
Species magister - Dungeness Crab
Genus Cancer
Species borealis - Cancer borealis
Species gracilis - Slender Crab
Species irroratus - Atlantic Rock Crab
Species productus - Red Rock Crab
Family Epialtidae - Kelp Crabs and Spider Crabs
Genus Libinia - Spider Crabs
Species dubia - Libinia dubia
Species emarginata - Portly Spider Crab
Genus Loxorhynchus
Species grandis - Sheep crab
Species crispatus - Masking Crab
Genus Pugettia
Species producta - Northern Kelp Crab
Genus Taliepus
Species nuttallii - Southern Kelp Crab
Family Gecarcinidae - Land Crabs
Genus Cardisoma
Species guanhumi - Blue Land Crab
Family Grapsidae - Marsh Crabs, Shore Crabs, and Talon Crabs
Genus Pachygrapsus
Species crassipes - Striped Shore Crab
Species transversus - Mottled Shore Crab
Genus Hemigrapsus
Species nudus - Purple Shore Crab
Species sanguineus - Japanese Shore Crab
Species oregonensis - Green Shore Crab
Genus Grapsus
Species grapsus - Sally Lightfoot Crab
Family Hepatidae
Genus Hepatus
Species epheliticus - Calico Crab
Family Inachidae
Genus Stenorhynchus
Species seticornis - Yellowline Arrow Crab
Family Leucosiidae
Genus Persephona
Species mediterranea - Mottled Purse Crab
Genus Randallia
Species ornata - Globose Sand Crab
Family Ocypodidae - Fiddler Crabs and Ghost Crabs
Genus Uca - Fiddler Crabs
Species crenulata - Mexican Fiddler Crab
Species longisignalis - Longwave Gulf Fiddler
Species minax - Red-jointed Fiddler Crab
Species pugilator - Atlantic Sand Fiddler Crab
Species pugnax - Atlantic Marsh Fiddler Crab
Species thayeri - Atlantic Mangrove Fiddler Crab
Genus Ocypode - Ghost Crabs
Species quadrata - Atlantic Ghost Crab
Family Panopeidae
Genus Dyspanopeus
Species sayi - Say's Mud Crab
Genus Panopeus
Species lacustris - Knot-fingered mud crab
Genus Lophopanopeus
Species bellus - Lophopanopeus bellus
Family Pilumnidae
Genus Pilumnus
Species sayi - Spineback Hairy Crab
Family Pinnotheridae - Pea Crabs
Genus Dissodactylus
Species mellitae - Sand-dollar Pea Crab
Genus Pinnixa
Species chaetopterana - Tube Pea Crab
Family Portunidae - Swimming Crabs
Genus Achelous
Species spinimanus - Achelous spinimanus
Genus Arenaeus
Species cribrarius - Speckled Swimming Crab
Genus Callinectes
Species ornatus - Callinectes ornatus
Species sapidus - Atlantic Blue Crab
Genus Carcinus
Species maenas - Green Crab
Genus Ovalipes
Species ocellatus - Lady Crab
Genus Portunus
Species sayi - Portunus sayi
Family Sesarmidae
Genus Aratus
Species pisonii - Mangrove Tree Crab
Genus Armases
Species cinereum - Squareback Marsh Crab
Family Ucididae
Genus Ucides
Species cordatus - Mangrove crab
Family Xanthidae - Mud Crabs
Genus Menippe
Species mercenaria - Menippe mercenaria
Infraorder Stenopodidea
Family Stenopodidae
Genus Stenopus
Species hispidus - Banded Coral Shrimp
Infraorder Caridea - Caridean shrimps
Family Crangonidae
Genus Crangon
Species septemspinosa - Crangon septemspinosa
Family Hippolytidae
Genus Lysmata
Species californica - Red Rock Shrimp
Genus Latreutes
Species fucorum - Latreutes fucorum
Family Palaemonidae
Genus Palaemon
Species elegans - Palaemon elegans
Species intermedius - Palaemon intermedius
Species pugio - Palaemon pugio
Species vulgaris - Palaemon vulgaris
Family Pandalidae
Genus Pandalus
Species platyceros - California Spot Prawn
Superorder Peracarida - Marsupial Crustaceans
Order Amphipoda - Amphipods
Suborder Senticaudata
Family Anisogammaridae
Family Bathyporeiidae
Genus Amphiporeia
Species virginiana - Amphiporeia virginiana
Family Calliopiidae
Genus Calliopius
Species laeviusculus - Calliopius laeviusculus
Family Caprellidae
Genus Aeginina
Species longicornis - Aeginina longicornis
Genus Caprella
Species californica - Caprella californica
Species mutica - Caprella mutica
Species verrucosa - Caprella verrucosa
Family Corophiidae
Genus Monocorophium
Species cylindricum - Monocorophium cylindricum
Family Crangonyctidae
Genus Crangonyx
Species gracilis - Crangonyx gracilis
Species richmondensis - Crangonyx richmondensis
Genus Stygobromus
Species pecki - Peck's Cave Amphipod
Species russelli - Stygobromus russelli
Family Gammaridae - Scuds
Genus Gammarus
Species fasciatus - Gammarus fasciatus
Species lacustris - Gammarus lacustris
Species locusta - Gammarus locusta
Species mucronatus - Gammarus mucronatus
Species seideli - Gammarus seideli
Species pseudolimnaeus - Gammarus pseudolimnaeus
Family Hadziidae
Genus Mexiweckelia
Species hardeni - Mexiweckelia hardeni
Family Hyalellidae
Genus Hyalella
Species wellborni - Hyalella wellborni
Species azteca - Hyalella azteca
Family Ischyroceridae
Genus Ericthonius
Species rubricornis - Ericthonius rubricornis
Genus Jassa
Species marmorata - Jassa marmorata
Family Talitridae - Beach Hoppers
Genus Americorchestia
Species megalophthalma - Americorchestia megalophthalma
Species longicornis - Americorchestia longicornis
Genus Arcitalitrus
Species sylvaticus - Lawn Shrimp
Genus Megalorchestia
Species californiana - California beach flea
Species corniculata - Megalorchestia corniculata
Genus Orchestia
Species grillus - Orchestia grillus
Genus Platorchestia
Species platensis - Platorchestia platensis
Genus Talitroides
Species alluaudi - Talitroides alluaudi
Genus Traskorchestia
Species traskiana - Traskorchestia traskiana
Genus Uhlorchestia
Species uhleri - Uhlorchestia uhleri
Family Unciolidae
Genus Unciola
Suborder Gammaridea
Family Haustoriidae
Genus Haustorius
Species canadensis - Haustorius canadensis
Suborder Hyperiidea
Family Hyperiidae
Genus Hyperia
Family Phronimidae
Genus Phronima
Order Isopoda - Isopods
Suborder Asellota - Asellotes
Superfamily Gnathostenetroidoidea
Superfamily Stenetrioidea
Superfamily Janiroidea
Family Janiridae
Genus Jaera
No Taxon albifrons complex
Species albifrons - Jaera albifrons
Genus Carpias
Species minutus - Carpias minutus
Superfamily Aselloidea - Waterslaters
Family Asellidae - Common Waterslaters
Genus Caecidotea
No Taxon forbesi group
Species racovitzai - Caecidotea racovitzai
Subspecies australis - Caecidotea racovitzai australis 0
Subspecies racovitzai - Caecidotea racovitzai racovitzai
Species communis - Caecidotea communis
Species tomalensis - Caecidotea tomalensis
No Taxon hobbsi group
Species kenki - Potamic Springslater
Genus Lirceolus
Genus Lirceus
Genus Asellus
No Taxon Arctasellus
No Taxon Asellus
Family Stenasellidae
Suborder Microcerberidea
No Taxon Scutocoxifera
Suborder Cymothoida - Predatory and Parasitic Isopods
Family Cirolanidae
Genus Bathynomus - Giant Isopods
Genus Cirolanides
Species texensis - Cirolanides texensis
Genus Excirolana
Species chiltoni - Excirolana chiltoni
Genus Cirolana
Infraorder Epicaridea - Crustacean-parasitic Isopods
Family Aegidae
Family Cymothoidae
Genus Anilocra
Species acuta - Anilocra acuta
Genus Elthusa
Species californica - Elthusa californica
Suborder Oniscidea - Woodlice
Infraorder Holoverticata
No Taxon Tylida
Family Tylidae
Genus Tylos
Species niveus - Tylos niveus
Species punctatus - Tylos punctatus
No Taxon Orthogonopoda
No Taxon Crinocheta
Family Alloniscidae
Genus Alloniscus
Species mirabilis - Alloniscus mirabilis
Species perconvexus - Alloniscus perconvexus
Family Armadillidae - Tropical and Southern Pillbugs
Genus Cubaris
Species benitensis - Cubaris benitensis
Species murina - Little Sea Pillbug
Genus Gabunillo - Gabunillo 0
Genus Venezillo
Species arizonicus - Venezillo arizonicus
Species microphthalmus - Venezillo microphthalmus
Species parvus - Venezillo parvus
Species pisum - Venezillo pisum 0
Family Armadillidiidae - European Pillbugs
Genus Armadillidium
Species vulgare - Common Pillbug
Species nasatum - Nosy Pillbug
Family Cylisticidae
Genus Cylisticus
Species convexus - Curly Woodlouse
Family Detonidae
Genus Armadilloniscus
Species coronacapitalis - Armadilloniscus coronacapitalis
Species holmesi - Armadilloniscus holmesi
Species lindahli - Armadilloniscus lindahli
Species ellipticus - Armadilloniscus ellipticus
Genus Detonella
Species papillicornis - Detonella papillicornis
Family Eubelidae
Genus Elumoides
Family Oniscidae - Sowbugs
Genus Oniscus
Species asellus - European Sowbug
Family Philosciidae
Genus Atlantoscia
Species floridana - Florida Fast Woodlouse
Genus Chaetophiloscia
Species sicula - Chaetophiloscia sicula
Genus Littorophiloscia
Species richardsonae - Littorophiloscia richardsonae
Species vittata - Littorophiloscia vittata
Genus Philoscia
Species muscorum - Philoscia muscorum
Family Platyarthridae
Genus Niambia
Species capensis - Niambia capensis
Genus Platyarthrus - Ant Woodlice
Species hoffmannseggii - Ant woodlouse
Species aiasensis - Platyarthrus aiasensis
Family Porcellionidae
Genus Acaeroplastes
Genus Porcellio
Species dilatatus - Giant Canyon Woodlouse
Species laevis - Swift Woodlouse
Species scaber - Common Rough Woodlouse
Species spinicornis - Brickwork Woodlouse
Genus Porcellionides
Species floria - Porcellionides floria
Species pruinosus - Plum Woodlouse
Species virgatus - Porcellionides virgatus
Genus Proporcellio
Species vulcanius - Proporcellio vulcanius
Family Trachelipodidae
Genus Nagurus
Species cristatus - Dwarf Gray Striped Isopod
Genus Trachelipus
Species rathkii - Rathke's Woodlouse
Family Rhyscotidae
Genus Rhyscotus
Species texensis - Rhyscotus texensis
No Taxon Synocheta
Family Styloniscidae
Genus Cordioniscus
Species stebbingi - Cordioniscus stebbingi
Family Trichoniscidae
Genus Androniscus
Species dentiger - Androniscus dentiger
Genus Brackenridgia
Species heroldi - Brackenridgia heroldi
Genus Haplophthalmus
Species danicus - Spurred Ridgeback
Genus Hyloniscus
Species riparius - Hyloniscus riparius
Genus Miktoniscus
Species medcofi - Miktoniscus medcofi
Species spinosus - Miktoniscus spinosus 0
Genus Trichoniscus
Species pygmaeus - Trichoniscus pygmaeus
Infraorder Diplocheta
Family Ligiidae - Seaslaters and Rockslaters
Genus Ligidium
Species blueridgensis - Ligidium blueridgensis
Species elrodii - Ligidium elrodii
Species gracile - Ligidium gracile
Species kofoidi - Ligidium kofoidi
Species lapetum - Ligidium lapetum
Species latum - Ligidium latum
Genus Ligia - Seaslaters
Species baudiniana - Ligia baudiniana
Species exotica - Wharf Roach
Species occidentalis - Western Seaslater
Species oceanica - European Seaslater
Species pallasii - Ligia pallasii
Suborder Valvifera - Valve-tailed Isopods
Family Chaetiliidae
Genus Saduria
Species entomon - Saduria entomon
Genus Chiridotea
Species coeca - sand isopod
Family Idoteidae
Genus Idotea
Species phosphorea - Idotea phosphorea
Species urotoma - Idotea urotoma
Species balthica - Idotea balthica
Species metallica - Idotea metallica
Genus Pentidotea
Species montereyensis - Pentidotea montereyensis
Species aculeata - Pentidotea aculeata
Species resecata - Eelgrass Isopod
Species wosnesenskii - Rockweed Isopod
Suborder Sphaeromatidea - Seapills and allies
Superfamily Sphaeromatoidea - Seapills
Family Sphaeromatidae - Typical Seapills
Genus Cassidinidea
Species ovalis - Cassidinidea ovalis
Genus Dynamenella
Genus Exosphaeroma
Species diminutum - "Exosphaeroma" diminutum
Species inornata - Exosphaeroma inornata
Genus Gnorimosphaeroma
Species noblei - Gnorimosphaeroma noblei
Species oregonense - Gnorimosphaeroma oregonense
Genus Paracerceis
Genus Sphaeroma
Species quadridentatum - Sphaeroma quadridentatum
Species papillae - Sphaeroma papillae
Genus Thermosphaeroma - Spring-Seapills
Species thermophilum - Socorro Isopod
Family Tecticipitidae
Family Ancinidae
Superfamily Seroloidea
Suborder Limnoriidea - Gribbles and Allies
Order Tanaidacea
Family Tanaididae
Genus Synaptotanais
Species notabilis - Synaptotanais notabilis
Genus Tanais
Species dulongii - Tanais dulongii
Family Leptocheliidae
Genus Hargeria
Species rapax - Hargeria rapax
Order Mysida - Mysid Shrimp
Family Mysidae
Order Stomatopoda - Mantis Shrimps
Family Squillidae
Genus Squilla
Species empusa - Squilla empusa