Diel-vertical-migration
Guides
Acartia
Acartia is a genus of marine calanoid copepods comprising the majority of species in the family Acartiidae. They are small, planktonic crustaceans found primarily in temperate coastal and estuarine waters worldwide. The genus includes ecologically important species such as A. tonsa, which is among the most abundant and well-studied estuarine copepods globally. Acartia species serve as key intermediaries in aquatic food webs and are increasingly used as model organisms for studying coastal plankton dynamics, thermal ecology, and phylogeographic patterns.
Bythotrephes longimanus
Spiny Water Flea, Spiny Waterflea
Bythotrephes longimanus is a predatory planktonic cladoceran crustacean native to northern Europe and Asia that has become a significant invasive species in North America since its introduction to the Great Lakes in the 1980s. Adults reach up to 15 mm in length, with females growing substantially larger than males. The species exhibits cyclic parthenogenesis and produces distinctive morphological forms depending on reproductive mode and season. Its invasion has caused substantial ecological disruption through direct predation on native zooplankton and non-lethal effects that alter prey behavior and population dynamics.
Chaoborus astictopus
Clear Lake gnat
Chaoborus astictopus is a phantom midge (family Chaoboridae) commonly known as the Clear Lake gnat. The species has a univoltine life cycle with adults emerging in spring. Older larvae exhibit diel vertical migration, occupying deep profundal zones during daylight hours and moving to open waters at night, indicating negative phototaxis. The species has been studied as a target for insecticide control and is known to host microsporidian and fungal pathogens.
Chaoborus festivus
phantom midge
Chaoborus festivus is a species of phantom midge in the family Chaoboridae, first described by Dyar and Shannon in 1924. The genus Chaoborus comprises aquatic midges known for their transparent, nearly invisible larvae that inhabit freshwater systems. Larvae are predatory and possess unique gas-filled sacs that aid in buoyancy control. Adults are short-lived and do not feed.
Chaoborus flavicans
phantom midge
Chaoborus flavicans is a phantom midge (Diptera: Chaoboridae) whose larval stages are important aquatic predators in lake ecosystems. Recent taxonomic revision indicates it represents a complex of at least four species, with C. flavicans sensu stricto primarily inhabiting lakes across the Holarctic region. Larvae are notable for their diel vertical migration behavior, which changes ontogenetically and serves as a predator avoidance mechanism against fish predation.
Crangon septemspinosa
sand shrimp, seven-spined bay shrimp
Crangon septemspinosa is a small caridean shrimp distributed along the Atlantic coast of North America from Newfoundland to eastern Florida. Adults reach 7–7.5 cm in length and exhibit sand-colored camouflage. The species is nocturnal, with activity levels and respiration rates increasing at higher temperatures. It occupies diverse marine habitats from intertidal zones to depths of 450 m, including eelgrass beds, salt marshes, and estuaries. Reproductive timing varies geographically: northern populations show bimodal spawning in spring and late autumn, while southern Gulf of St. Lawrence populations reproduce more continuously through spring and summer with reduced autumn activity.
Nepidae
waterscorpions, water scorpions, water stick insects, needle bugs
Nepidae is a family of exclusively aquatic predatory true bugs containing approximately 250 species in 14 genera. Members are commonly called waterscorpions due to their superficial resemblance to scorpions, possessing raptorial forelegs and a long caudal respiratory siphon. The family is divided into two subfamilies: Nepinae (broad, flat-bodied 'water scorpions') and Ranatrinae (slender 'water stick insects'). They occur on all continents except Antarctica, inhabiting stagnant or slow-moving freshwater habitats.
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.
Penilia avirostris
Penilia avirostris is a marine cladoceran crustacean in the family Sididae, distributed across temperate and tropical coastal waters worldwide. It is a holoplanktonic species that exhibits cyclical parthenogenesis, with populations shifting between asexual and sexual reproduction in response to environmental cues. The species has been observed to undergo diel vertical migration and shows strong sensitivity to temperature, with optimal growth around 18°C but tolerance ranging from 12°C to 30°C. Population dynamics are closely tied to seasonal temperature fluctuations, with dramatic increases reported in warming waters.