Copepods are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic, some are benthic, a number of species have parasitic phases, and some continental species may live in limnoterrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds, puddles, damp moss, or water-filled recesses of plants (phytotelmata) such as bromeliads and pitcher plants. Many live underground in marine and freshwater caves, sinkholes, or stream beds. Copepods are sometimes used as biodiversity indicators.
Tantulocarida is a highly specialised group of parasitic crustaceans that consists of about 33 species, treated as a class in superclass Multicrustacea. They are typically ectoparasites that infest copepods, isopods, tanaids, amphipods and ostracods.
The Cyclopoida are an order of small crustaceans from the subclass Copepoda. Like many other copepods, members of Cyclopoida are small, planktonic animals living both in the sea and in freshwater habitats. They are capable of rapid movement. Their larval development is metamorphic, and the embryos are carried in paired or single sacs attached to first abdominal somite.
Ergasilidae is a widespread family of copepods and comprises many species. The type genus is Ergasilus. With a few doubtful exceptions all ergasilids are parasitic on fishes.
Calamoecia is a genus of copepods in the family Centropagidae confined to Australasia. It is thought to have evolved since the separation of the Australian continent from Antarctica. Three of the Australian endemic species are listed as vulnerable species on the IUCN Red List. The genus contains the following species:
Monstrilloida is an order of copepods with a cosmopolitan distribution in the world's oceans. The order contains a single family, Monstrillidae. The name of the first ever described genus Monstrilla is derived from latin, meaning "tiny monster", because the lack of usual diagnostic features of copepods puzzled early taxonomists.
Bomolochidae is a family of copepods parasitic on marine fishes. Most species parasitize the gills of fish, but some species live in the nostrils or on the eyes of their hosts. The family contains just over 150 species from the following genera:
Hamaticolax unisagittatus is a species of parasitic copepod belonging to the family Bomolochidae. It is a parasite on the gills of the common snook and has only been recorded in coastal waters off Rio de Janeiro State. In one study over half of the host fish sampled in this area carried this parasite.
Paralubbockia longipedia is a species of copepod, and the only member of the family Paralubbockiidae. The family is characterised by the ventral position of the fifth legs, the possession of a separate maxillary palp, and the form of the endopods of the legs and antennae. The closest relatives of Paralubbockia are the family Oncaeidae. Initially placed among the Poecilostomatoida, Paralubbockia is now considered part of the Cyclopoida.
Acartia teclae is a species of copepod belonging to the family Acartiidae. This species was discovered when specimens previously identified as Acartia clausi were examined and found to belong to a separate species. This species appears to have a similar range to, and occupies similar brackish estuarine habitats as, Acartia lefevreae but differs in the absence of spines on the dorsal part of the posterior body segment (metasome).
Centropagidae is a family of copepods in the order Calanoida. Its members are particularly known as plankton in coastal waters and in fresh water in Australia and southern South America. They are also found on subantarctic islands and in lakes in Antarctica.
Tegastidae is a family of copepods, which are characterised by having laterally compressed bodies, a claw-like mandible in the nauplius stage, and by a modified male genital complex. 85 species have been described in 6 genera. Two species of Smacigastes are found at hydrothermal vents, while the remaining species are found in shallow water, associated with algae, bryozoans and cnidarians, such as corals.
Lernaeocera branchialis, sometimes called cod worm, is a parasite of marine fish, found mainly in the North Atlantic. It is a marine copepod which starts life as a small pelagic crustacean larva. It is among the largest of copepods, ranging in size from 2 to 3 millimetres when it matures as a copepodid larva to more than 40 mm as a sessile adult.
Gaussia is a genus of copepods. The genus contains bioluminescent species. It is a "characteristic genus of the mesopelagial", occurring at depths of 0–3,000 metres (0–9,843 ft). The genus Gaussia contains the following species:
Pennella is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host and enter into its skin. The males are free swimming. Due to their large size and mesoparasitic life history there have been a number of studies of Pennella, the members of which are among the largest of the parasitic Copepoda. All species are found as adults buried into the flesh of marine bony fish, except for a single species, Pennella balaenopterae which can be found in the muscles and blubber of cetaceans and occasionally other marine mammals, and is the largest species of copepod.
Pennella balaenopterae is a large ectoparasitic copepod specialising in parasitising marine mammals. It is the largest member of the genus Pennella, the other species of which are parasites of larger marine fish.
Lepeophtheirus pectoralis is a species of parasitic copepod from the northeast Atlantic Ocean, and the type species of the genus Lepeophtheirus. It is a parasite of flatfish, with the European flounder, the plaice, and the dab as the most frequent hosts. It feeds on the mucus, skin, and blood of the fish, with egg-producing females infecting the pectoral and pelvic fins of the host, while immature individuals and males are found on the rest of the body.
Peniculisa is a genus of marine parasitic copepods in the family Pennellidae.
Longipedia is a genus of marine copepods of the family Longipediidae, order Canuelloida.
Ergasilus curticrus is a freshwater parasitic copepod named in 2015. Described from the Orinoco river basin, it was found solely to be hosted by individuals of the Characiform fish species Bryconops giacopinii. Of those located in South America, it is one of only five species in its genus to be found outside of Brazil.
