User:John Bratton

Ephippium, pl. ephippia. A hard drought resistant case which some Cladocera or water fleas (Crustacea) produce to protect their resting eggs. In many Cladocera, when resting eggs are produced, the part of the valves covering the brood pouch becomes thickened and often much darkened. When the animal moults, this specialised structure separates from the rest of the valves and closes over the egg or eggs, forming a protective covering referred to as an ephippium on account of its saddle-like shape in many cases. Ephippia may float on the water surface, providing a means of dispersal for the species by currents, wind or birds. Ephippia are most highly developed in the Daphniidae and Macrothricidae. They occur in less developed states in the Bosminidae and many Chydoridae. They do not occur in the other families. (Scourfield, D.J., & Harding, J.P. 1966. A key to the British freshwater Cladocera with notes on their ecology. 3rd edn. Freshwater Biological Association Scientific Publication, no. 5.).