See text 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.

[2] However, their most distinctive anatomical trait is the presence of a joint between the fifth and sixth body segments.

[2] 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.

[2] Many commercial fish are dependent on calanoid copepods for diet in either their larval or adult forms.