Crustacea
Guides
Caecidotea kenki
Caecidotea kenki is a spring-dwelling asellid isopod found in the eastern United States. Originally described as Asellus kenki by Bowman in 1967, it is one of only three asellid species in Maryland habitually associated with springs rather than subterranean caves. It is distinguished from the six obligate cave-dwelling Caecidotea species in the region by its surface water habitat preference.
Caecidotea racovitzai racovitzai
Caecidotea racovitzai racovitzai is a subspecies of freshwater isopod in the family Asellidae. It was originally described as Asellus racovitzai racovitzai by Williams in 1970. The subspecies is known from Vermont, United States. As a member of the genus Caecidotea, it inhabits freshwater environments.
Cirolanidae
Cirolanidae is a family of aquatic isopod crustaceans established by Dana in 1852. The family encompasses approximately 70 genera and over 500 species, ranging from small interstitial forms to the supergiant deep-sea isopods of the genus Bathynomus that can exceed 30 cm in length. Members occupy diverse aquatic habitats including marine coastal waters, deep-sea environments, freshwater systems, and subterranean groundwater. The family is characterized by dorsoventrally flattened bodies and includes both free-living and troglobitic species.
Eurycercus longirostris
Eurycercus longirostris is a Holarctic cladoceran crustacean first described by Hann in 1982. A 2011 taxonomic revision synonymized E. vernalis with E. longirostris due to lack of morphological and genetic justification for their separation. The species has a broader distributional range than previously recognized and belongs to the subgenus Eurycercus (Eurycercus). As a member of the Eurycercidae family, it shares characteristics with other chydorid-like cladocerans including a rounded carapace and specialized feeding appendages.
Hepatidae
Hepatidae is a family of marine decapod crustaceans within the order Decapoda. The family was historically recognized to contain certain crab-like taxa, though its current taxonomic status and composition remain subjects of revision in modern crustacean systematics. Members of this group are marine organisms with characteristic decapod features including ten walking legs and a segmented body plan. The family's validity and scope have been debated, with some authorities synonymizing it with other families or reclassifying its constituent genera.
Hippolytidae
broken-back shrimp, cleaner shrimp, anemone shrimp, hump-backed shrimps
Hippolytidae is a family of marine caridean shrimp commonly known as broken-back shrimp, cleaner shrimp, or anemone shrimp. The family was redefined in 2023, with several former genera transferred to other families (Bythocariidae, Lysmatidae, Merguiidae, Thoridae), leaving 16 genera in Hippolytidae sensu stricto. Some members engage in cleaning symbiosis with fish, removing parasites and debris from host bodies. The family shows both diurnal and nocturnal activity patterns, with behavioral differences in cleaning site preferences.
Ilyocryptus
water fleas
Ilyocryptus is a genus of freshwater cladocerans (water fleas) in the family Ilyocryptidae. Species in this genus are characterized by a benthic lifestyle, inhabiting lake sediments and muddy substrates. The genus has a global distribution with notable diversity in the Neotropics and Far East. Several species groups have been identified, including the widespread I. spinifer group and the sarsi-group, with some taxa showing complex biogeographic patterns across transitional zones between boreal and tropical regions.
Lepadiformes
stalked barnacles, goose barnacles
Lepadiformes is an order of stalked barnacles within the class Maxillopoda. Members possess a fleshy peduncle that attaches the capitulum (shell) to substrates, distinguishing them from sessile acorn barnacles. The order includes approximately nine extant families, with Lepadidae being the most species-rich. Many species are epibiotic, attaching to mobile marine hosts including crustaceans, elasmobranchs, and marine debris.
Leptocheliidae
Leptocheliidae is a family of small, low-mobility crustaceans in the order Tanaidacea, comprising over 30 genera and 140 described species. Members are abundant in shallow marine waters and show high sensitivity to environmental shifts, particularly dissolved oxygen and temperature changes. Global diversity patterns reveal a bimodal latitudinal distribution with peaks in lower latitudes and decline at the equator, with biodiversity hotspots in the Indo-Australian region, Central Indo-Pacific, Gulf of Mexico, and Caribbean. The family serves as an important indicator group for monitoring environmental change in threatened coastal habitats.
Palaemon intermedius
Striped Shrimp
Palaemon intermedius is a species of caridean shrimp in the family Palaemonidae. It is endemic to temperate waters of southeastern Australia. The species is characterized by its translucent body with distinctive red spots and narrow stripes. It is a marine species with limited available ecological data.
Petrolisthes armatus
Green Porcelain Crab
Petrolisthes armatus, commonly known as the green porcelain crab, is a small porcellanid crab native to the southwestern Atlantic, particularly Brazil. The species has established invasive populations along the southeastern United States coast, where densities can exceed 30,000 individuals per square meter. Genetic studies confirm it as a single monophyletic species with exceptional geographic range spanning the Atlantic and eastern Pacific. It is frequently parasitized by the bopyrid isopod Aporobopyrus curtatus, which causes parasitic castration.
invasive-speciesfilter-feederparasite-hostintertidalporcelain-craboyster-reefsymbiosisplanktonic-larvaevisual-ecologycrustaceandecapodanomuraporcellanidaesouthwestern-atlanticeastern-pacificsoutheastern-united-statesbopyrid-parasiteAporobopyrus-curtatusestuarinemangrovesponge-symbiosisgaze-stabilizationachromatic-visionlarval-transportoyster-bedballast-wateraquaculturemonophyleticcryptic-species-complexparasitic-castrationzoeamegalopapleopodspermatophorechellipedcarapacegranulatedolive-greenblue-colorationFarol-IslandBrazilGeorgiaSouth-CarolinaFloridaPanamaCosta-RicaEcuadorPeruBaja-CaliforniaCaribbeanGulf-of-MexicoWest-IndiesAscension-IslandBermudaBahamasWest-Africarock-rubblesoft-sedimentshallow-subtidallower-intertidaldensity-30000-per-square-meter6-8-mm0.5-gorange-spotfour-segmented-chelipedantennae-outside-eyesvestigial-fourth-leg-pairfeathery-mouthpartszooplanktonscavengerpheromone-settlement-cue3-mm-sexual-maturity17%-parasite-prevalencebranchial-chamber-parasitesynchronous-growth-parasite-hostcastrationvisual-noisecaustic-flickerpolarization-sensitivityoptomotor-assaytidal-creekspectrally-narrow-environmentmitochondrial-DNAgenetic-variabilityexceptional-rangepre-Canal-Panama18591930s-Floridalineagewarm-temperate-Atlanticspecies-complexhalf-crabsquat-lobster-relativetrue-crabfalse-crabDecapodaMalacostracaArthropodaCrustaceaGibbes-1850Porcellana-armatagreen-porcelain-crabPetrolisthes-armatusRandallia
Randallia is a genus of true crabs in the family Leucosiidae, established by Stimpson in 1857. The genus comprises approximately 17 described species. These crabs belong to the diverse brachyuran crab fauna and are classified within the subfamily Ebaliinae. Members of this genus are marine decapod crustaceans.
Simocephalus
water flea
Simocephalus is a genus of freshwater cladoceran crustaceans commonly known as water fleas. Members exhibit the characteristic cladoceran life cycle with alternating parthenogenetic and sexual reproduction phases. The genus has been studied extensively for reproductive biology, with environmental factors such as temperature, food concentration, crowding, and illumination influencing life history traits.
Talitroides
landhopper, lawn shrimp
Talitroides is a genus of terrestrial amphipod crustaceans commonly known as landhoppers or lawn shrimp. These small, laterally compressed crustaceans have adapted to life on land, inhabiting moist soil and leaf litter in forested environments. Several species have been introduced outside their native ranges and have become established in new regions, including T. topitotum in Brazil and Hong Kong. The genus has been documented in mosquito surveillance bycatch studies and ecological research on soil fauna.
Thecostraca
Barnacles and Allies
Thecostraca is a class of marine crustaceans encompassing over 2,200 described species, with barnacles (subclass Cirripedia) comprising the vast majority. The group includes three major lineages: sessile suspension-feeding barnacles, parasitic ascothoracidans that infect cnidarians and echinoderms, and the enigmatic Facetotecta, known only from planktonic larvae. Members undergo distinctive larval development, typically featuring a nauplius stage followed by a cypris stage that facilitates settlement. Thecostraca exhibits remarkable life history diversity, ranging from free-living suspension feeders to endoparasites with highly derived morphologies.
Trophithauma rostrata
Trophithauma rostrata is a spider crab species in the family Inachidae, formerly classified under the genus Macropodia. Molecular genetic analysis (COI barcode) demonstrated that Macropodia parva should be synonymised with T. rostrata, while M. longipes was determined to be a synonym of M. tenuirostris. The species occurs in the Atlantic and Mediterranean regions. Like other inachid crabs, it exhibits epibiosis, carrying algae and other sessile organisms on its carapace.