Daphnia longispina typically has a slender body, with the head making up approximately one-third of the carapace’s margin, which is deeply concave. Its abdominal spine is relatively long, and the ventral eyespot on the head is small, positioned midway between the eye and the dorsal edge. It possesses a smooth helmet and an optic vesicle that touches the margin of the head. Reproduction occurs through parthenogenesis.