What is an ephippium in anomopod branchiopods?

In anomopod branchiopods, an ephippium is a saddlelike, chitinous thickening that forms over the brood pouch. When shed, this structure functions as a protective, bivalve capsule that houses fertilized, dormant eggs.1

These eggs are highly resistant to harsh environmental conditions, such as freezing or drying, allowing the species to survive periods of drought or cold. While many anomopods reproduce through parthenogenesis under favorable conditions, the production of these resistant eggs—often triggered by food scarcity or sudden temperature changes—ensures the survival of the population until conditions become favorable again.2