Rotaria neptunia is characterized by its extended, whirling motion. Among bdelloid rotifers, this species stands out for having the longest foot, which has the unique ability to be retracted. This retractable foot adaptation allows R. neptunia to thrive in relatively thick layers of mud, setting it apart from other bdelloid rotifers, which typically have shorter feet. In terms of its body structure, R. neptunia exhibits bilateral symmetry, and like all organisms, it is multicellular in terms of cellularity.