[1] Its colouration is highly variable, ranging from brown or red to green, which accounts for its common name of "chamaeleon shrimp".

The two can be differentiated by the following characters:[1] Praunus flexuosus was the first mysidacean species ever to be formally described, when Otto Friedrich Müller described it under the name Cancer flexuosa in 1776.

[1] It is "the only documented non-native marine zooplankton species established on the East Coast [of North America]".

[10] It is an omnivore, feeding on debris and preying on small crustaceans, especially harpacticoid copepods,[11] but consumes a greater proportion of macrozooplankton than other common littoral mysids, such as Neomysis integer and Praunus inermis.

[9] When it detects a predator nearby, using a combination of visual and chemical cues, P. flexuosus hides among vegetation.