An order of carnivorous branchiopod crustaceans formerly included in the order Cladocera. Only one species, the fresh-water Leptodora kindti, is included.
The body is about 9 mm (0.4 in.) long. Leptodora is among the most transparent of multicellular freshwater animals. It swims slowly by means of enormous antennae and seizes its prey with its six pairs of segmented, grasping, thoracic limbs. The mandibles are styliform and of a type unique within the Branchiopoda. There is a single, median sessile eye. The carapace is reduced to a dorsal brood pouch and does not protect the body.
Parthenogenetic eggs and young are carried in the brood pouch in summer. In autumn, fertilized resting eggs are carried there which are shed freely, and the eggs overwinter. They hatch in spring as nauplii, a stage eliminated from the parthenogenetic phase of the life cycle.
Leptodora is widely distributed in the plankton of larger lakes of the Holarctic region. See also Branchiopoda.
