During copulation, the male clam shrimp grasps the ventral edge of the female shell and deposits a spermatophore in side the female's carapace by extending his abdomen. The eggs are brooded inside the female's shell and are shed at the time of the female molt. Breeding is constant throughout the adult life of clam shrimps, and the female sheds eggs with every molt. Conchostracans usually produce two kinds of eggs: vegetative and asexual eggs, known as summer eggs, and more resistant, dry-season or winter eggs that are usually sexually produced. The summer eggs possess a thin shell and they might develop parthenogenetically or be fertilized; their development is rapid and they may hatch while still attached to the female. The winter eggs possess a thick shell and, in some species, they can remain dormant for long periods of time. Winter eggs are produced in lesser numbers and their production might be stimulated by external factors such as population density, temperature, and photoperiod. With the exception of the family Cyclestheriidae, the eggs of clam shrimps hatch as a nauplius larva that develops quickly into an adult without undergoing metamorphosis, although the acquisition of the carapace gives a false impression of metamorphosis. The family Cyclestheriidae reproduces mostly by parthenogenesis, with the eggs hatching in a brood pouch attached to the female and developing into replicas of the adult before being released without a naupliar stage.
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