Freshwater
Guides
Caecidotea racovitzai australis
Caecidotea racovitzai australis is a subspecies of freshwater isopod in the family Asellidae. It was originally described as Asellus racovitzai australis by Williams in 1970. The subspecies belongs to a genus of aquatic isopods commonly found in groundwater and cave habitats.
Calamoceratidae
Calamoceratidae is a family of caddisflies comprising approximately 9 genera and at least 120 described species. The family is distributed across tropical and temperate regions worldwide, with notable diversity in the Neotropics. Larvae are aquatic and construct distinctive cases from plant material. The genus Phylloicus is particularly species-rich in the New World, with 66 described species.
Callicorixa
Callicorixa is a genus of water boatmen (family Corixidae) comprising nine described species. Members are aquatic insects inhabiting freshwater environments. Research on *Callicorixa vulnerata* has demonstrated sexual size dimorphism and tarsal asymmetry in mid-leg morphology. *Callicorixa praeusta* exhibits complex acoustic communication, with males producing synchronized stridulatory calls for congregation and reproduction.
Cambaridae
Cambarid Crayfishes
Cambaridae is the largest family of freshwater crayfish, comprising over 400 species. The family is predominantly native to eastern North America and Mexico, with a small number of species in eastern Asia (genus Cambaroides) and the Caribbean (Cuba). Several species have become invasive outside their native ranges, while many others have restricted distributions and are threatened with extinction.
Cambarus asperimanus
mitten crayfish
Cambarus asperimanus, commonly known as the mitten crayfish, is a species of freshwater crayfish in the family Cambaridae. It was first described by Faxon in 1914 and is native to North America. The species holds a Least Concern conservation status according to the IUCN, last reviewed in 2010.
Cambarus bartonii
common crayfish, Appalachian brook crayfish, Eastern Crayfish
Cambarus bartonii is a freshwater crayfish native to eastern North America, first described from North America in 1798. It inhabits fast-flowing, cool, rocky streams and shallow lakes across a broad range from Ontario and New Brunswick south to Alabama. The species exhibits notable physiological tolerance to acidic conditions and demonstrates behavioral flexibility, including documented use of terrestrial microhabitats for overwintering. Several subspecies have been proposed but their validity remains under investigation.
Cambarus bartonii bartonii
Common Crayfish
Cambarus bartonii bartonii is a subspecies of freshwater crayfish native to eastern North America. It is a secondary burrowing species found in streams and other aquatic habitats, with documented physiological tolerance to acidic conditions. The subspecies exhibits agonistic behavioral contests between males, particularly during reproductive periods when males adopt Form I morphology with enlarged claws. It has been observed using terrestrial microhabitats for overwintering.
Cambarus robustus
Big Water Crayfish, robust crayfish
Cambarus robustus, commonly known as the Big Water Crayfish or robust crayfish, is a freshwater crayfish species in the family Cambaridae. It is native to eastern North America, ranging from several U.S. states to Ontario, Canada. The species has been studied extensively as a surrogate for federally endangered crayfish species due to its close phylogenetic relationships and similar ecological requirements. Research indicates it demonstrates significant acid tolerance compared to sympatric Orconectes species, exhibits complex agonistic behaviors with distinct initiation acts predicting contest outcomes, and occupies a partitioned trophic position in multi-species crayfish communities.
Cambarus speciosus
Beautiful Crayfish
Cambarus speciosus, commonly known as the beautiful crayfish, is a species of freshwater crayfish in the family Cambaridae. It is endemic to Georgia, United States. The species is currently listed as Near Threatened (NT) by the IUCN, with a stable population as of the last review in 2010. The specific epithet 'speciosus' refers to its attractive appearance.
Cannaphila insularis
gray-waisted skimmer
Cannaphila insularis, commonly known as the gray-waisted skimmer, is a dragonfly species in the family Libellulidae. The species includes two recognized subspecies: C. i. insularis (nominate) and C. i. funerea. It is distributed across the Caribbean, Central America, and North America, with the nominate subspecies occurring on Hispaniola, Jamaica, and Isla de Pinos (Cuba), while C. i. funerea ranges from southern Texas through Colombia and is widely distributed in Cuba. The species inhabits lentic freshwater environments including lagoons, ponds, and slow-moving streams with abundant herbaceous vegetation. The last instar larva of C. i. funerea has been formally described, providing diagnostic morphological characters for identification.
Cardiocladius
Cardiocladius is a genus of non-biting midges in the family Chironomidae, subfamily Orthocladiinae. These aquatic insects are part of the diverse group of chironomid flies commonly known as bloodworms, though adults do not feed on blood. The genus was established by Jean-Jacques Kieffer in 1912. Larval stages are aquatic and contribute to freshwater food webs.
Caridea
caridean shrimp, true shrimp
Caridea is a species-rich infraorder of decapod crustaceans comprising over 3,000 described species of true shrimp. Members are distinguished from other shrimp groups by their brooding reproductive strategy, lamellar gill structure, and characteristic abdominal segmentation where the second segment overlaps both the first and third. They occupy diverse aquatic habitats from freshwater streams to abyssal depths exceeding 5,000 meters, with roughly one-quarter of species inhabiting freshwater environments. The group includes commercially significant species such as Pandalus borealis and ecologically important cleaner shrimp that maintain reef fish health.
Celina
Celina is a genus of small predaceous diving beetles (family Dytiscidae) first described by Aubé in 1837. These aquatic beetles belong to the subfamily Hydroporinae and tribe Methlini. The genus occurs primarily in the Neotropical region, with records from northern South America including Colombia. Members of this genus are aquatic predators inhabiting freshwater environments.
Celithemis elisa
Calico Pennant
Celithemis elisa, commonly known as the calico pennant, is a dragonfly species in the family Libellulidae native to eastern North America. Adults are small to medium-sized (24–34 mm body length) with distinctive brown spots at the wing bases and tips. The species inhabits calm freshwater bodies with emergent vegetation and exhibits spatial partitioning of perching microhabitats when co-occurring with congeners.
Celithemis fasciata
Banded Pennant
Celithemis fasciata, commonly known as the banded pennant, is a dragonfly species in the skimmer family Libellulidae native to the eastern and central United States. Adults are approximately 33 mm in length and are distinguished by extensive, sharply defined black markings on the wings, though wing pattern intensity varies geographically with northern individuals showing less coloration. The species inhabits lentic waters including ponds, lakes, and ditches. Research has demonstrated that individuals exhibit prey preference for small dipteran prey over larger alternatives and engage in prey switching behavior based on relative prey densities.
Cenocorixa wileyi
Cenocorixa wileyi is a species of water boatman in the family Corixidae. It was described by Hungerford in 1930. The genus Cenocorixa is endemic to western North America and contains several species adapted to lentic freshwater habitats. This species is part of a genus characterized by distinctive male genitalic structures and specific habitat preferences.
Centrocorisa nigripennis
Centrocorisa nigripennis is a species of water boatman in the family Corixidae, first described by Fabricius in 1803. It belongs to the suborder Heteroptera (true bugs) within the order Hemiptera. The genus Centrocorisa is part of the tribe Corixini, a group of aquatic insects commonly known as water boatmen. As a member of the Nepomorpha, it is adapted to an aquatic lifestyle. The species has been recorded across the Caribbean, Middle America, and North America.
Centropagidae
Centropagidae is a family of calanoid copepods comprising 14 genera and over 130 species. Members occupy diverse aquatic habitats including marine coastal waters, freshwater lakes, and saline lakes across the Southern Hemisphere, with notable concentrations in Australia, southern South America, subantarctic islands, and Antarctica. The family exhibits significant habitat diversity: marine genera include Centropages, Dussartopages, and Gladioferens; freshwater genera include Boeckella, Calamoecia, and Hemiboeckella. The genus Boeckella poppei represents the only terrestrial/freshwater invertebrate reported from all three main Antarctic biogeographic regions (subantarctic islands, maritime Antarctic, and continental Antarctic).
Cercopagididae
Cercopagididae is a family of predatory branchiopod crustaceans in the order Onychopoda. Members are planktonic water fleas characterized by specialized predatory adaptations including modified thoracopods and distinctive labral morphology. The family includes notable invasive species such as Bythotrephes longimanus (spiny water flea) and Cercopagis pengoi (fishhook water flea), which have been introduced to North America and pose significant threats to aquatic ecosystems. Native to the Palearctic, several species have expanded their ranges through human-mediated dispersal.
Chauliodes pectinicornis
Summer Fishfly
Chauliodes pectinicornis, commonly known as the Summer Fishfly, is a species of fishfly in the family Corydalidae native to eastern North America. First described by Carl Linnaeus in 1763, this species has a notably wide distribution across eastern Canada and the United States. A distinctive ecological feature is its commensal relationship with Plecopteracoluthus downesi larvae, which complete their entire life cycle including pupation on the fishfly's mesothorax.
Cheumatopsyche
Little Sister Sedges
Cheumatopsyche is a large genus of net-spinning caddisflies comprising at least 240 described species. Larvae construct silk capture nets to filter food from flowing water and are important components of freshwater benthic communities. Species exhibit variable life histories including univoltine and multivoltine cycles, with some populations capable of producing additional generations when thermal conditions permit. The genus is widely distributed across multiple continents and serves as a significant bioindicator for water quality assessment.
Cheumatopsyche analis
Cheumatopsyche analis is a species of netspinning caddisfly in the family Hydropsychidae. It belongs to a genus known for constructing fixed capture nets in flowing water to filter food particles. The species has been documented in the Nearctic region, including Hawaii. As a member of the Hydropsychidae, it participates in freshwater food webs as both a filter-feeder larva and a flying adult.
Chilostigmodes
Chilostigmodes is a genus of caddisflies in the family Limnephilidae, tribe Chilostigmini. It was established by Martynov in 1914. The genus is poorly documented, with only three observations recorded on iNaturalist as of 2024. It belongs to the diverse Limnephiloidea superfamily, whose members are primarily associated with freshwater habitats.
Chilostigmodes areolatus
Chilostigmodes areolatus is a species of caddisfly in the family Limnephilidae, first described by Walker in 1852. It belongs to the tribe Chilostigmini, a group of limnephilid caddisflies primarily associated with lentic (still-water) habitats. The genus Chilostigmodes is small and poorly studied, with limited published information on the biology of its constituent species.
Chimarra
Little Black Caddisflies
Chimarra is a large genus of caddisflies (Trichoptera: Philopotamidae) containing more than 630 described species. Adults are commonly known as "little black caddisflies" due to their characteristic dark coloration. The genus has undergone extensive radiation, with species distributed across multiple continents including North America, South America, Europe, Africa, and Asia. Molecular studies have investigated the evolutionary history and biogeographic patterns of diversification within this genus.
Chironominae
non-biting midges
Chironominae is a subfamily of non-biting midges (Diptera: Chironomidae) containing over 2,000 described species across three tribes: Chironomini, Pseudochironomini, and Tanytarsini. Members are globally distributed and primarily aquatic in their immature stages. The subfamily includes economically and ecologically significant genera such as Chironomus, Polypedilum, and Tanytarsus. Adults are characterized by reduced mouthparts and do not feed; larvae are diverse in habitat specialization, ranging from freshwater lakes and rivers to marine environments and phytotelmata.
Chironomini
non-biting midges
Chironomini is a diverse tribe of non-biting midges within the family Chironomidae. Adults are mosquito-like in appearance but lack piercing mouthparts and are harmless to humans. Larvae are primarily aquatic and play significant roles in freshwater food webs. The tribe contains numerous genera distributed across multiple continents, with species occupying varied freshwater habitats from oligotrophic lakes to eutrophic waters.
Chironomus staegeri
Chironomus staegeri is a non-biting midge (Diptera: Chironomidae) characterized by extensive chromosomal inversion polymorphism. Populations exhibit significant genetic differentiation between deep and shallow water habitats in North America, with inversion patterns suggesting possible incipient speciation. The species has been used as a standard test organism in aquatic ecotoxicology studies, particularly for heavy metal toxicity research.
Chloroperlinae
Chloroperlinae is a subfamily of stoneflies within the family Chloroperlidae, established by Okamoto in 1912. Members are commonly known as green stoneflies due to their characteristic coloration. The subfamily occurs across multiple continents in cold freshwater habitats. Adults emerge from aquatic environments to inhabit riparian zones.
Chydorus
Chydorus is a genus of small benthic-littoral cladocerans in the family Chydoridae, established by William Elford Leach in 1816. Species in this genus are characterized by rounded, often reticulated carapaces and are among the most common anomopods in freshwater systems worldwide. The genus exhibits cosmopolitan distribution with multiple centers of diversification in Europe and Asia, and includes ecologically significant species such as Chydorus sphaericus, which dominates eutrophic waters and plays important roles in food web dynamics involving cyanobacteria.
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.
Cirolanides
Cirolanides is a genus of eyeless isopods in the family Cirolanidae, first described by Benedict in 1896. The genus contains two species: C. texensis and C. wassenichae. Members are characterized by reduced visual structures and specialized appendages adapted for subterranean life. These crustaceans represent a lineage adapted to dark, aquatic habitats.
Claassenia sabulosa
Shortwing Stonefly, short-wing stone
Claassenia sabulosa, commonly known as the shortwing stonefly, is a species of common stonefly in the family Perlidae. It is found in North America, with documented populations in the western United States including Colorado, as well as Canada. The species has been studied for its life cycle dynamics in Colorado streams and its adult mate-finding behaviors.
Cladotanytarsus
Cladotanytarsus is a genus of non-biting midges (Chironomidae) containing over 80 described species with worldwide distribution, particularly diverse in the Holarctic region. The genus comprises two subgenera: Cladotanytarsus s. str. and Lenziella. Species are primarily lacustrine, with adults often associated with lake surroundings and larvae inhabiting freshwater sediments. Several species have been described from experimentally acidified lakes in North America, demonstrating tolerance to varying pH conditions. One species, C. lewisi, is a significant human allergen source in Sudan.
Clarkhydrus
Clarkhydrus is a genus of diving beetles in the family Dytiscidae, established in 2018 by Fery & Ribera. The genus was erected to accommodate species previously placed in related genera within the subtribe Deronectina. As a member of the subfamily Hydroporinae, these beetles are small to medium-sized aquatic predators. The genus is relatively recently described, and research on its species-level diversity and ecology is ongoing.
Climacia
spongillaflies
Climacia is a genus of spongillaflies in the family Sisyridae, containing more than 20 described species. Larvae of this genus are obligate associates of freshwater sponges, feeding on sponge tissues. Adults are short-lived and non-feeding. The genus is found in freshwater habitats across North America.
Clinocerinae
aquatic dance flies
Clinocerinae is a subfamily of dance flies (Empididae) comprising 16 recognized genera including Clinocera, Wiedemannia, Dolichocephala, Trichoclinocera, and Kowarzia. Members are commonly known as aquatic dance flies due to their strong association with freshwater habitats. The subfamily has a global distribution with particularly diverse faunas in the Palaearctic and Oriental regions. Multiple generic revisions and species-level revisions have been published for Nearctic, Palaearctic, and Oriental faunas.
Clostoeca
Clostoeca is a genus of northern caddisflies in the family Limnephilidae, established by Banks in 1943. The genus is monotypic, containing only one described species: Clostoeca disjuncta. As a member of the Limnephilidae family, it belongs to a group of caddisflies commonly known as northern caddisflies, which are predominantly found in cool, temperate regions.
Coelotanypus atus
Coelotanypus atus is a species of non-biting midge in the family Chironomidae, described by Roback in 1971. It belongs to the subfamily Tanypodinae, a group of predatory midges commonly found in aquatic habitats. The genus Coelotanypus contains relatively few described species and is distinguished by specific morphological features of the adult and larval stages.
Coenagrion
Eurasian Bluets, Northern Bluets
Coenagrion is a genus of damselflies in the family Coenagrionidae, commonly called Eurasian Bluets or Northern Bluets. Species are generally medium-sized with bright coloration. While predominantly Eurasian in distribution, three species occur in North America: C. angulatum, C. interrogatum, and C. resolutum. The genus exhibits phenotypic plasticity in thermal adaptation, with high-latitude populations showing significant thermal adaptation capacity.
Colobaea
snail-killing flies
Colobaea is a genus of 15 valid species of snail-killing flies in the family Sciomyzidae. Larvae of all reared species kill and consume freshwater nonoperculate pulmonate snails, with varying degrees of specialization. The genus occurs in both Palearctic and Nearctic regions.
Colymbetes longulus
Colymbetes longulus is a species of diving beetle in the family Dytiscidae, first described by LeConte in 1862. It belongs to the subfamily Colymbetinae, a group of predatory aquatic beetles. The genus Colymbetes is among the more diverse genera of diving beetles, with species distributed across the Northern Hemisphere. Like other members of its family, this species is adapted to life in freshwater habitats.
Copelatinae
copelatine diving beetles
Copelatinae is a subfamily of predaceous diving beetles (Dytiscidae) comprising seven genera: Agaporomorphus, Aglymbus, Copelatus, Exocelina, Lacconectus, Liopterus, and Madaglymbus. The genus Copelatus is the largest with approximately 470 described species worldwide, showing greatest diversity in tropical South America, Africa, and Southeast Asia. Members are predominantly aquatic, though some species have colonized highly ephemeral habitats including forest floor depressions. The subfamily exhibits remarkable morphological diversity and includes phylogenetically isolated lineages such as the South African genus Capelatus.
Copelatus distinctus
Copelatus distinctus is a species of diving beetle described by Aubé in 1838. It belongs to the genus Copelatus within the subfamily Copelatinae of the family Dytiscidae. The species is recorded from Middle America based on available distribution data. Like other members of Copelatus, it is an aquatic predator inhabiting freshwater environments.
Copelatus glyphicus
Copelatus glyphicus is a small diving beetle in the family Dytiscidae, described by Thomas Say in 1823. Adults measure 4.2–4.6 mm in length and 2.1–2.5 mm in width. The species is widely distributed across eastern North America.
Corisella
water boatmen
Corisella is a genus of water boatmen in the family Corixidae, established by Lundblad in 1928. The genus contains approximately five described species distributed in the Americas. Members are aquatic true bugs inhabiting freshwater environments. One species, Corisella edulis, has been documented as a host for the peritrich ciliate epibiont Orbopercularia lichtensteini in Mexico.
Corisella edulis
water boatman
Corisella edulis is a species of water boatman in the family Corixidae. It is found in Central America and North America. The species has been documented as a host for the peritrich ciliate epibiont Orbopercularia lichtensteini in Hidalgo, Mexico.
Corixidae
Water Boatmen, Lesser Water Boatmen
Corixidae is a family of aquatic true bugs in the order Hemiptera, commonly known as water boatmen or lesser water boatmen. The family comprises approximately 500 species across 33-55 genera distributed worldwide in freshwater habitats, with a few species inhabiting saline waters. Members are distinguished from similar aquatic bugs by their right-side-up swimming posture, flattened body shape, and modified front legs adapted for feeding. The family exhibits diverse feeding strategies including herbivory, carnivory, detritivory, and omnivory.
Corixinae
water boatman
Corixinae is a subfamily of aquatic true bugs comprising at least 130 described species. Members are commonly known as water boatmen and are found in freshwater habitats worldwide. The subfamily includes the genera Corixa and Sigara, among others. Larvae develop through five instars, with distinct morphometric and chaetotaxy characteristics separating developmental stages.
Corixoidea
water boatmen, pygmy water boatmen
Corixoidea is a superfamily of aquatic true bugs (Nepomorpha) containing two families: Corixidae (water boatmen) and Micronectidae (pygmy water boatmen). Members are exclusively aquatic, inhabiting ponds, slow-moving streams, and other freshwater bodies. The superfamily is distinguished by adaptations for underwater life including modified antennae with mechanoreceptive and chemoreceptive sensilla, and diverse feeding strategies ranging from detritivory to predation. Corixidae is the larger family with approximately 500 species worldwide, while Micronectidae contains smaller-bodied species with distinct antennal morphology supporting its family-level recognition.