Which branchiopods lack a carapace?

Within the class Branchiopoda, the presence of a carapace is a common but not universal feature. While many branchiopods possess a protective plate or shell, the following groups lack a carapace:1

• Order Anostraca: Commonly known as fairy shrimps and brine shrimps, these elongated crustaceans are characterized by the absence of a carapace and the presence of stalked compound eyes.234
• Order Lipostraca: This is an extinct group known only from the fossil record, specifically the Devonian period.23

While other branchiopod groups, such as the infraorders Onychopoda and Haplopoda, have a carapace, it is significantly reduced in these forms, serving only as a dorsal brood pouch rather than a structure that encloses the trunk or limbs.23