Originally, it was thought that Isoxys was related to another bivalved arthropod from the Cambrian, Tuzoia, due to the similar aspects of their carapaces.

Currently the group has been placed into the Deuteropoda, a proposed clade of arthropods whose members are distinguished by an anatomical reorganization of the head region, including the appearance of a differentiated first appendage pair (the 'deutocerebral' pair), a multisegmented head, and a hypostome/labrum complex,[5][6][7] being placed outside the crown group of Arthropoda, with both Mandibulata and Chelicerata being more closely related to each other than to isoxyids.

[1] Species of the Isoxydia are thought to have been actively swimming predators, using their frontal appendages to capture soft-bodied prey, with the frontalmost pairs of biramous limbs aiding in food processing.

[1] The various species of the order are thought to have occupied a variety of niches, from swimming just above the seafloor (nektobenthic) to open ocean swimmers (pelagic).

[1] Isoxyid species with elongated carapace spines are likely to have engaged in vertical migration up and down the water column, like many modern marine invertebrates.