Freshwater
Guides
Ecnomidae
Tubecase Netspinning Caddisflies
Ecnomidae is a family of caddisflies (Trichoptera) comprising approximately 375–400 described species across 9 genera. The family exhibits a characteristic Gondwanan distribution pattern, with all genera restricted to the Southern Hemisphere except Ecnomus, which is also widespread in the Palearctic and Oriental regions. Larvae are aquatic and construct fixed silk retreats on submerged surfaces. The family's taxonomy has been historically unstable, having been classified as a subfamily of both Hydropsychidae and Psychomiidae before recognition as a monophyletic family closely related to Polycentropodidae.
Einfeldia
non-biting midges
Einfeldia is a genus of non-biting midges in the subfamily Chironominae, tribe Chironomini, within the bloodworm family Chironomidae. The genus was established by Kieffer in 1924 and contains approximately 11 described species distributed across Europe, North America, and other regions. At least one species, E. synchrona, has been studied in detail and exhibits univoltine life history with synchronized adult emergence.
Elmidae
Riffle beetles
Elmidae, commonly known as riffle beetles, is a family of aquatic beetles in the superfamily Byrrhoidea containing over 150 genera and 1,500 described species. Both adults and larvae are primarily aquatic, inhabiting fast-flowing shallow areas of streams and rivers such as riffles. Adults breathe underwater using a plastron—a microfilm of air held by microscopic hairs on their body surface that enables oxygen diffusion from the water. The family has significant value in freshwater biomonitoring due to their sensitivity to water pollution.
Elminae
riffle beetles
Elminae is a subfamily of riffle beetles (family Elmidae) comprising at least 120 genera and over 1,300 described species. Members are primarily aquatic, inhabiting running water habitats across all major biogeographic regions. The subfamily exhibits considerable morphological diversity, with some genera showing pronounced secondary sexual dimorphism and miniaturization traits.
Elophila gyralis
Waterlily Borer Moth
Elophila gyralis, commonly known as the waterlily borer moth, is a species of aquatic moth in the family Crambidae. It was first described by George Duryea Hulst in 1886. The species is distributed across eastern North America, ranging from Canada through the eastern and central United States. Its common name suggests an association with waterlily plants, though specific larval host details require further documentation.
Elophila icciusalis
pondside pyralid moth, Pondside Crambid Moth
Elophila icciusalis, commonly known as the pondside pyralid moth, is a small crambid moth native to most of North America. The species has a wingspan of 16–26 mm and is active from June through September. Its larvae are fully aquatic, feeding on submerged aquatic vegetation in freshwater habitats. Three subspecies are recognized: E. i. albiplaga, E. i. avalona, and the nominate E. i. icciusalis.
Elophila occidentalis
Elophila occidentalis is a small crambid moth described by William Harry Lange in 1956. The species exhibits sexual dimorphism in wing size, with females notably larger than males. Adults are active during summer months with multiple generations per year. Larvae are aquatic and feed on submerged aquatic plants.
Enallagma concisum
Cherry Bluet
Enallagma concisum, commonly known as the cherry bluet, is a narrow-winged damselfly species in the family Coenagrionidae. It is endemic to the Eastern United States, where it inhabits freshwater habitats. The species is currently classified as Least Concern by the IUCN, with a stable population and no immediate threats to its survival. As a member of the genus Enallagma, it belongs to one of the most species-rich damselfly genera in North America.
Enallagma recurvatum
Pine Barrens Bluet, Pale Barrens Bluet
Enallagma recurvatum is a small damselfly endemic to the United States. It inhabits freshwater lakes, particularly in pine barrens and similar sandy, acidic lake systems. The species is considered threatened due to habitat loss from development, water quality degradation, and shoreline alteration. Its restricted range and specialized habitat requirements make it vulnerable to environmental changes.
Enallagma semicirculare
Claw-tipped Bluet
Enallagma semicirculare, commonly known as the claw-tipped bluet, is a damselfly species in the family Coenagrionidae. It occurs primarily in Mexico and the southwestern United States, with documented records from Arizona, New Mexico, and southern Texas. The species was described by Edmond de Sélys Longchamps in 1876. Like other members of the genus Enallagma, it is a small, slender damselfly associated with freshwater habitats.
Enallagma signatum
Orange Bluet
The orange bluet (Enallagma signatum) is a species of damselfly in the family Coenagrionidae. It is a small, slender odonate found across eastern North America. The species was first described by Hagen in 1861 and has been subject to taxonomic revision, including work by Rosser Garrison who published a revision of the genus Enallagma in 1984. Like other members of its genus, it is associated with freshwater habitats where it completes its aquatic larval development.
Endochironomus
Endochironomus is a genus of non-biting midges in the bloodworm family Chironomidae. The genus was established by Kieffer in 1918 and contains at least six described species distributed across Europe and North America. Members belong to the subfamily Chironominae and tribe Chironomini. As with other chironomid midges, adults do not feed and lack functional mouthparts.
Enochrus cinctus
Water Scavenger Beetle
Enochrus cinctus is a species of water scavenger beetle in the family Hydrophilidae. It is native to North America, with documented records across much of the United States and southern Canada. As a member of the Hydrophilidae, it is an aquatic beetle associated with freshwater habitats. The species was originally described by Thomas Say in 1824 under the basionym Hydrobius cinctus.
Enochrus pygmaeus pectoralis
Enochrus pygmaeus pectoralis is a subspecies of water scavenger beetle in the family Hydrophilidae. It belongs to a genus of small aquatic beetles commonly found in lentic and slow-flowing lotic habitats. The subspecies designation indicates geographic variation within the widespread E. pygmaeus species complex. Like other members of the genus, it likely occupies shallow freshwater environments and exhibits the characteristic clubbed antennae and ventral swimming hairs typical of hydrophilid beetles.
Enochrus sayi
Enochrus sayi is a species of water scavenger beetle in the family Hydrophilidae. It occurs across much of eastern and central North America, with introduced populations in the Hawaiian Islands. The species inhabits freshwater aquatic environments.
Eoparargyractis
Eoparargyractis is a genus of aquatic moths in the family Crambidae, subfamily Acentropinae. Described by Lange in 1956, it contains three recognized species distributed in North America. The genus belongs to a group of moths whose larvae are adapted to freshwater habitats. Species include E. floridalis, E. irroratalis, and E. plevie.
Ephemerella aurivillii
spiny crawler mayfly
Ephemerella aurivillii is a spiny crawler mayfly in the family Ephemerellidae with a strict one-year life cycle. The species occurs across northern regions of the Northern Hemisphere, including Europe, northern Asia, and North America. Research in Norway demonstrated that its distribution and growth rates are strongly temperature-dependent, with populations expanding following hydropower-induced warming of previously cold streams.
Ephemerella invaria
Sulphur Dun
Ephemerella invaria, commonly known as the sulphur dun, is a species of spiny crawler mayfly in the family Ephemerellidae. It occurs in headwater streams across eastern North America, from southeastern and northern Canada through the eastern United States. The species has been studied for population genetic impacts associated with deforestation of its stream habitats. As a member of the Ephemerellidae, it belongs to a group of mayflies characterized by distinctive spiny or tuberculate body features.
Ephemerellidae
Spiny Crawler Mayflies
Ephemerellidae, commonly known as spiny crawler mayflies, is a family of mayflies (Ephemeroptera) comprising approximately 90 species across 8-14 genera. The family is distributed throughout North America and the UK, with additional records from Europe and Asia. Nymphs inhabit lotic-erosional environments including flowing streams of all sizes, lake shores, and beaches with wave action. They are primarily collector-gatherers and serve as important indicators of water quality due to their sensitivity to pollution.
Ephemeridae
Burrowing Mayflies
Ephemeridae is a family of large mayflies comprising approximately 150 described species distributed worldwide except Australia and Oceania. Adults range up to 35 mm in length and possess either two or three elongated caudal filaments. Many species exhibit distinctively patterned wings. The family is commonly known as "burrowing mayflies" due to the fossorial adaptations of their nymphs, which inhabit silty or sandy substrates in freshwater systems. Nymphs possess specialized morphological features including spur-like projections on foretibiae, dorsally positioned plumose and lanceolate abdominal gills, and mandibular tusks that facilitate burrowing behavior.
Epischura
Epischura is a genus of freshwater calanoid copepods in the family Temoridae. The genus contains approximately 11 recognized species, including the well-studied Epischura lacustris of North American lakes and the endemic Epischura baikalensis of Lake Baikal. Species within this genus exhibit diverse feeding strategies ranging from omnivory to predation, with documented consumption of both phytoplankton and zooplankton prey. The genus has been proposed as paraphyletic with respect to Heterocope, with suggestions to transfer the Siberian species E. baikalensis and E. chankensis to the resurrected genus Epischurella.
Epischura lacustris
Epischura lacustris is a predatory calanoid copepod in the family Temoridae. It inhabits freshwater lakes across northeastern North America, including all five Great Lakes. The species exhibits size-selective predation on small zooplankton, particularly Bosmina longirostris, and has been observed to consume both phytoplankton and animal prey. It can be distinguished from other Great Lakes calanoids by three stout caudal setae on each caudal ramus and a noticeably bent urosome in mature specimens.
Erythemis mithroides
Claret Pondhawk
Erythemis mithroides, commonly known as the claret pondhawk, is a neotropical dragonfly in the family Libellulidae. It is a medium-sized, brightly colored species with distinctive red coloration in males. The species occupies a wide geographic range across the Americas, from the southern United States through Central America and South America, and is frequently encountered in both natural and artificial lentic water bodies. It is an active predator with territorial males that exhibit aggressive behaviors during mate-finding and foraging activities.
Erythrodiplax fervida
Red-mantled Dragonlet
Erythrodiplax fervida, commonly known as the Red-mantled Dragonlet, is a small dragonfly in the family Libellulidae. The species occurs in the Caribbean and South America, with records from Cuba, Colombia, and Mexico. It is one of five Antillean Erythrodiplax species found in Cuba. The last instar larva was formally described in 2007, filling a gap in the taxonomic knowledge of Cuban dragonflies. The IUCN lists the species as Least Concern with a stable population.
Estelloxus
Estelloxus is a genus of mites in the family Lebertiidae, order Trombidiformes. The genus was established by Habeeb in 1963 and belongs to the superfamily Lebertioidea. Members of this genus are predatory or parasitic mites associated with freshwater or semi-aquatic habitats. The genus is poorly known, with limited published information on species diversity and biology.
Eubranchipus serratus
Ethologist Fairy Shrimp
Eubranchipus serratus is a fairy shrimp species in the family Chirocephalidae, first described by Forbes in 1876. It is one of approximately 300 species of Anostraca, commonly known as fairy shrimp, which are specialized for temporary aquatic habitats. The species has been documented across North America, though specific ecological details remain limited in published sources.
Eubrianax edwardsii
water penny beetle
Eubrianax edwardsii is a species of water penny beetle in the family Psephenidae, found in North America. Water penny beetles are aquatic insects with flattened, disc-shaped larvae that cling to rocks in streams and rivers. The family Psephenidae is a small group of beetles specialized for life in flowing freshwater habitats.
Eurycercus
Eurycercus is a genus of large-bodied cladoceran crustaceans (water fleas) and the sole genus of the monotypic family Eurycercidae. Species reach up to 6 mm in length, making them among the largest anomopods. The genus contains 16 described species distributed across four subgenera, with a primarily Holarctic distribution and some extensions into the Neotropics and Southern Hemisphere. Species occupy littoral zones of freshwater lakes and ponds, often associated with submerged vegetation.
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.
Eurypterida
sea scorpions, eurypterids
Eurypterida is an extinct order of aquatic chelicerate arthropods commonly known as sea scorpions. They ranged from the Cambrian through the Permian periods, with their main diversification occurring during the Paleozoic. The group includes both marine and freshwater species, with body sizes ranging from a few centimeters to over two meters in some species. Eurypterids are characterized by a segmented body with a prosoma and opisthosoma, paired swimming paddles, and a terminal telson spine. They represent one of the largest arthropod groups in the fossil record and are significant for understanding early chelicerate evolution.
Euthycera
Euthycera is a genus of marsh flies in the family Sciomyzidae, commonly known as snail-killing flies. The genus contains approximately 30 described species distributed primarily across the Palearctic region. Members of this genus are predators or parasitoids of freshwater snails and slugs, making them significant biological control agents. The genus was established by Latreille in 1829 and is classified within the tribe Tetanocerini.
Farula
Farula is a genus of caddisflies in the family Uenoidae, established by Milne in 1936. The genus belongs to the subfamily Uenoinae and is part of the Limnephiloidea superfamily. As a uenoid genus, Farula likely comprises small to medium-sized caddisflies associated with freshwater habitats. The genus has not been extensively documented in public observation databases.
Faxonius immunis
papershell crayfish
Orconectes immunis, commonly known as the papershell crayfish, is a freshwater crayfish native to central North America that has become invasive in parts of Canada. The species has been documented in southwestern Ontario and Lake of the Woods, where it shows preferences for shallow waters with fine substrates and aquatic vegetation. Reproductive studies indicate significant egg mortality during incubation, with females exhibiting size-dependent fecundity. The species has been subject to cellular-level studies of oogenesis, demonstrating intracellular yolk synthesis in oocytes.
Faxonius luteus
Golden Crayfish
Faxonius luteus, commonly known as the Golden Crayfish, is a freshwater crustacean in the family Cambaridae. It is native to North America, with documented presence in the United States. The species was first described by Creaser in 1933. Like other members of the genus Faxonius, it inhabits freshwater environments. The specific epithet "luteus" refers to its golden or yellowish coloration.
Faxonius palmeri
Gray-speckled Crayfish
Faxonius palmeri is a freshwater crayfish in the family Cambaridae, commonly known as the Gray-speckled Crayfish. It was originally described as Cambarus palmeri by Faxon in 1884 and later transferred to the genus Faxonius. The species is native to North America, with documented occurrences in the United States.
Faxonius virilis
Northern Crayfish, Virile Crayfish
Orconectes virilis is a medium-sized freshwater crayfish native to North America, widely distributed across Canada and the northern United States. The species is notable for its well-documented behavioral ecology, including complex social hierarchies, territorial home range behavior, and sophisticated predator avoidance mechanisms. It has been extensively studied as a model organism for agonistic behavior, chemical communication, and escape response mechanics. The species is currently expanding its range westward into Alberta and shows adaptability to varying environmental conditions, though acidification poses reproductive challenges.
Gammaridae
gammarids, scuds
Gammaridae is a family of amphipod crustaceans with a distribution centered on Eurasia. The family exhibits euryhaline tolerance as a lineage, inhabiting environments from freshwater to marine waters. Historically, Gammaridae served as a wastebin taxon for numerous gammaridean amphipods, many of which have since been reassigned to separate families including Anisogammaridae, Melitidae, and Niphargidae. In North America, members are commonly referred to as scuds.
Gammaridea
Gammaridea was historically recognized as a suborder of Amphipoda encompassing approximately 7,275 species (92% of described amphipods) across ~1,000 genera and ~125 families. The group included nearly all freshwater amphipods alongside numerous marine species. Taxonomic revisions by Lowry and Myers (2003–2017) demonstrated that Gammaridea was paraphyletic, leading to its deconstruction into new suborders: Corophiidea (2003), Senticaudata (2013), and Amphilochoidea (2017). The name Gammaridea is no longer recognized as a valid taxon in current amphipod classification.
Gammarus
scuds, freshwater shrimp, sideswimmers
Gammarus is a genus of amphipod crustaceans in the family Gammaridae, containing over 200 described species and representing one of the most species-rich crustacean genera. Species occupy diverse aquatic habitats ranging from purely freshwater to estuarine and marine environments, with salinity tolerance varying markedly among species. The genus is widely distributed throughout the Holarctic region, with additional species extending into tropical Southeast Asia. Gammarus species serve important ecological functions as shredders and predators in aquatic food webs.
Gammarus fasciatus
Gammarus fasciatus is a freshwater amphipod native to North America. Laboratory studies demonstrate that food type significantly influences growth rates, with algae and animal matter supporting greater growth than detritus-based diets. The species serves as a host for the acephaline gregarine parasite Ganymedes oaklandi. In the Great Lakes region, populations have declined due to competition with the invasive Ponto-Caspian amphipod Echinogammarus ischnus.
Gammarus pseudolimnaeus
Northern Spring Amphipod
Gammarus pseudolimnaeus is a freshwater amphipod crustacean inhabiting lotic (flowing water) environments in North America. The species exhibits complex behavioral ecology, including size-selective predation vulnerability to fish predators such as brook trout and sculpins, and chemically-mediated responses to predation risk that influence reproductive behavior. Population dynamics are characterized by univoltine (single annual) generation cycles with high mortality during early life stages and winter periods. The species serves as an important prey item in stream food webs and has been extensively studied as a model organism for freshwater invertebrate ecology, toxicology, and predator-prey interactions.
freshwaterloticamphipodpredator-preybehavioral-ecologytoxicologyunivoltineNorth-Americamodel-organismstream-ecologysize-selective-predationchemical-ecologyparasitismacanthocephalacopper-toxicitymate-guardingcalceolimicrohabitat-selectionthigmotaxisdiel-activityseasonal-dynamicsproduction-ecologydriftbrook-troutsculpinOntarioVirginiaGammaridaecrustaceaninvertebratesenticaudataBousfield-1958Northern-Spring-AmphipodGammarus seideli
Seidel's Scud
Gammarus seideli is a species of freshwater amphipod in the family Gammaridae, described in 2018. It is one of numerous Gammarus species found in North American freshwater systems. The species is recognized by iNaturalist with the common name "Seidel's Scud" and has been documented in a small number of observations. As a relatively recently described species, detailed ecological and biological information remains limited.
Gelastocoris oculatus
Big-eyed Toad Bug
Gelastocoris oculatus, commonly known as the big-eyed toad bug, is a riparian predator in the family Gelastocoridae. It inhabits freshwater margins across North and Central America, where its cryptic coloration and hopping locomotion resemble small toads. The species captures smaller insects by leaping onto them and subduing them with piercing-sucking mouthparts. Both adults and nymphs are predatory, with females depositing eggs under rocks or in sand or mud.
Gerris
water striders
Gerris is a genus of water striders (family Gerridae) comprising 43 species in three subgenera (Gerris, Gerriselloides, and Macrogerris). Species in this genus inhabit freshwater surfaces across temperate regions, where they use surface tension to walk on water. The genus has become a model system for studying sexual conflict, with well-documented antagonistic coevolution between males and females over mating control.
Gerris buenoi
water strider
Gerris buenoi is a small water strider species native to North America, first described in 1911. Adults measure 8-10 mm in length and possess elongated mid-legs adapted for locomotion on water surfaces. The species exhibits wing polymorphism, with multiple wing forms corresponding to different seasons and environmental conditions. It has been extensively studied as a model organism for sexual conflict research and was the first water strider to have its genome sequenced.
Gerroidea
Water Striders and Ripple Bugs
Gerroidea is a superfamily of semiaquatic true bugs (Hemiptera: Heteroptera) comprising at least three families—Gerridae (water striders), Veliidae (smaller water striders or riffle bugs), and Hermatobatidae—with over 2,000 described species. Members are specialized for life on the water surface, utilizing water-repellent legs and surface tension to remain afloat. The group occupies diverse aquatic habitats ranging from freshwater ponds and streams to marine coastal environments including mangroves and open ocean. Recent research has documented significant undescribed diversity in tropical regions and novel bacterial symbiont associations.
Gomphurus
clubtails
Gomphurus is a genus of dragonflies in the family Gomphidae, commonly known as clubtails. The genus was elevated from subgenus rank within Gomphus in recent taxonomic revisions, reflecting distinct morphological and genetic characteristics. It contains approximately 13 described species, primarily distributed in North America. Species within this genus are associated with lotic freshwater habitats and exhibit restricted geographic ranges.
Grammotaulius
Grammotaulius is a genus of caddisflies in the family Limnephilidae, established by Kolenati in 1848. The genus contains species distributed across Europe and North America, including at least two recognized species: G. alascensis and G. bettenii. As limnephilid caddisflies, members of this genus are aquatic in their larval stages and terrestrial as adults.
Graphoderus
Graphoderus is a genus of predaceous diving beetles in the family Dytiscidae, comprising 12 extant species and 2 extinct species known from fossils. The genus is native to the Holarctic region, with species distributed across Europe, North America, and parts of Asia. Several species are of conservation concern, particularly G. bilineatus, which is listed in Annexes II and IV of the European Habitats Directive and has experienced significant population declines across its range.
Graphoderus perplexus
predacious diving beetle
Graphoderus perplexus is a predaceous diving beetle in the family Dytiscidae, described by Sharp in 1882. It is distributed across the Holarctic region, occurring in both North America and the Palearctic. Like other members of its genus, it is an aquatic predator inhabiting freshwater environments. The species is part of the tribe Aciliini, which includes other medium to large diving beetles.