Seasonal changes in the body shape of cladoceron – Daphnia is due to the influence of

Cyclomorphosis Seasonal change in body shape found in rotifers (phylum Rotifera), and in cladoceran Crustacea (phylum Arthropoda). In cladocerans, e.g. Daphnia species, the changes in shape involve the head, which is rounded from midsummer to spring and then progressively becomes helmet-shaped from spring to summer, reverting to the rounded shape by midsummer. The process is poorly understood and may be the result of genetic factors interacting with external conditions, e.g. temperature or day length, density of water.