Conchostracans are commonly known as clam shrimp due to their outward resemblance to bivalve mollusks. All con-chostracans are laterally flattened and possess a bivalve carapace, joined by a dorsal hinge or fold with the two halves connected and controlled by a strong adductor muscle. This carapace covers the entire body and limbs (or almost), and, in most cases, is marked by concentric lines of growth. The trunk is divided into 10-32 segments, each with a pair of appendages. The second pair of antennae is well developed and biramous, and the compound eyes are sessile. Conchostracans can be distinguished from other groups of the Branchiopoda because their bodies are completely enclosed within the carapace and because they possess a comparatively reduced abdomen. They range in size from a few millimeters to up to 0.7 in (1.7 cm). Their color is usually translucent to pale, although some species might present a pink, reddish, or orange coloration because of the presence of hemoglobin in the haemolymph; the shell color varies from translucent to dark brown.
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