Cold-water
Guides
Capnura
small winter stoneflies
Capnura is a genus of small winter stoneflies in the family Capniidae, established by Banks in 1900. The genus contains approximately seven described species distributed primarily in North America. These stoneflies are part of the winter-emerging group of Plecoptera, with adults typically active during cold months when most other insects are inactive.
Chloroperlidae
Green Stoneflies, Green Sallies, Yellow Sallies, Yellow Sallflies
Chloroperlidae is a family of stoneflies comprising over 200 species across 22 genera, commonly known as green stoneflies for their characteristic yellowish-green to green coloration. Adults range from 6–20 mm in body length and are distinguished by relatively short cerci, slender labial palps, and wings pads that remain parallel to the body midline. The family exhibits hemimetabolous development with egg, nymph, and adult stages but no pupal stage. Nymphs are aquatic inhabitants of cold, clean streams and rivers across five continents, where their sensitivity to pollutants makes them important bioindicators of water quality. Adults are primarily terrestrial, dwelling in riparian vegetation near water bodies with a brief lifespan focused on reproduction.
Eucapnopsis brevicauda
short-tailed snowfly
Eucapnopsis brevicauda is a small winter stonefly in the family Capniidae, commonly known as the short-tailed snowfly. It has a transpacific distribution spanning North America and eastern Asia, with confirmed records from Canada, the United States, Mongolia, Russia, and South Korea. Adults emerge during late winter to spring and are typically found in association with cold, running water in sub-montane stream habitats. The species was previously misidentified as E. quattuorsegmentata in Korean records.
Lithodidae
King Crabs, Stone Crabs
Lithodidae is a family of large, cold-water decapod crustaceans commonly known as king crabs or stone crabs. Members possess a crab-like body form within the otherwise hermit crab-associated infraorder Anomura, representing an independent evolutionary transition to the crab morphology. The family includes commercially important species such as the red king crab (Paralithodes camtschaticus) and encompasses both deep-water and intertidal habitats across cold seas of the Northern and Southern Hemispheres.
Megarcys
springflies
Megarcys is a genus of springflies in the family Perlodidae, comprising approximately 11 described species. The genus was established by Klapálek in 1912. Species occur primarily in cold-water habitats across northern regions of North America and Asia. Megarcys belongs to the tribe Arcynopterygini within the subfamily Perlodinae.
Pandalus
cold-water prawn
Pandalus is a genus of medium-sized cold-water shrimp in the family Pandalidae, inhabiting marine benthic environments primarily in northern seas. Members are protandric hermaphrodites, beginning life as males and transitioning to females with age. Several species support significant commercial fisheries, including P. borealis (northern shrimp), P. jordani (pink shrimp), and P. platyceros (spot prawn). The genus exhibits characteristic vertical diel migrations and variable nursery habitat associations across species.
Paralithodes
king crab
Paralithodes is a genus of large king crabs (family Lithodidae) native to cold waters of the North Pacific Ocean, including the Bering Sea, Okhotsk Sea, and Sea of Japan. The genus contains commercially important species, particularly the red king crab (P. camtschaticus). These crabs undergo a biphasic life cycle with distinct larval stages (zoeae, glaucothoe) before reaching the juvenile phase. Molecular studies indicate that early larval stages lack adaptations to elevated temperature and hypoxia, requiring stable environmental conditions for survival.
Pediciidae
Hairy-eyed Crane Flies
Pediciidae, commonly known as hairy-eyed crane flies, is a family of about 500 species worldwide. They are medium-sized to large flies (5–35 mm) closely related to true crane flies (Tipulidae). The family is distinguished by pubescent compound eyes with short erect hairs between the facets, a trait absent in related families. They occupy diverse habitats but are particularly associated with clean, cold aquatic environments. The family was established as a separate lineage from Tipulidae based on morphological and molecular evidence, representing one of two primary lineages within the superfamily Tipuloidea.
Saduria entomon
Saduria entomon is a large benthic isopod crustacean and one of the largest crustaceans in the Baltic Sea, reaching nearly 9 cm in length. It is distributed across Arctic and northern Pacific coasts, the brackish Baltic Sea (where it is a glacial relict), several North European lakes, and has been introduced to the Black Sea. The species is sexually dimorphic with males growing larger and maturing at larger sizes than females. It functions primarily as a predator and scavenger, with documented cannibalism and feeding on other benthic invertebrates.
Utacapnia logana
Logan Snowfly
Utacapnia logana is a small winter-emerging stonefly in the family Capniidae, commonly known as the Logan Snowfly. It is native to the Rocky Mountain region of the western United States, where it inhabits cold, clean mountain streams. Adults emerge during winter months, a trait characteristic of the Capniidae family. The species was originally described as Capnia logana in 1965 before being transferred to the genus Utacapnia.
Zapada
forestflies, spring stoneflies, little brown stoneflies
Zapada is a genus of small spring stoneflies in the family Nemouridae, commonly known as forestflies or little brown stoneflies. The genus contains at least 10 described species distributed across western North America, from Alaska and the Rocky Mountains to California. Adults are 5–8 mm in body length and emerge in early spring, often February through April depending on elevation and species. Nymphs are aquatic shredders that process leaf litter and other organic matter in cold, well-oxygenated streams.