Calanoida is an order of copepods, a group of arthropods commonly found as zooplankton. The order includes around 46 families with about 1800 species of both marine and freshwater copepods between them. The largest specimens reach long, but most do not exceed long.
- Acartiidae
- Aetideidae
- Arctokonstantinidae
- Arietellidae
- Augaptilidae
- Bathypontiidae
- Calanidae
- Candaciidae
- Centropagidae
- Clausocalanidae
- Diaixidae
- Diaptomidae
- Discoidae
- Epacteriscidae
- Eucalanidae
- Euchaetidae
- Fosshageniidae
- Heterorhabdidae
- Hyperbionycidae
- Kyphocalanidae
- Lucicutiidae
- Megacalanidae
- Mesaiokeratidae
- Metridinidae
- Nullosetigeridae
- Paracalanidae
- Parapontellidae
- Parkiidae
- Phaennidae
- Pontellidae
- Pseudocyclopidae
- Pseudocyclopiidae
- Pseudodiaptomidae
- Rhincalanidae
- Rostrocalanidae
- Ryocalanidae
- Scolecitrichidae
- Spinocalanidae
- Stephidae
- Sulcanidae
- Temoridae
- Tharybidae
- Tortanidae
Ecology
Calanoid copepods are the dominant animals in the plankton in many parts of the world's oceans, making up 55–95% of plankton samples. They are therefore important in many food webs, taking in energy from phytoplankton and algae and 'repackaging' it for consumption by higher trophic level predators.