Fertilized eggs normally develop into free-swimming nauplii (= ovoviviparous reproduction)
(Fig. 4.1.12.) which are released by the mother. In extreme conditions (e.g. high salinity, low
oxygen levels) the embryos only develop up to the gastrula stage. At this moment they get
surrounded by a thick shell (secreted by the brown shell glands located in the uterus), enter a
state of metabolic standstill or dormancy (diapause) and are then released by the female (=
oviparous reproduction) (Fig. 4.1.14.). In principle both oviparity and ovoviviparity are found
in all Artemia strains, and females can switch in-between two reproduction cycles from one
mode of reproduction to the other. The cysts usually float in the high salinity waters and are
blown ashore where they accumulate and dry. As a result of this dehydration process
the diapause mechanism is generally inactivated; cysts are now in a state of quiescence
and can resume their further embryonic development when hydrated in optimal hatching
conditions.
Under optimal conditions brine shrimp can live for several months, grow from nauplius to
adult in only 8 days’ time and reproduce at a rate of up to 300 nauplii or cysts every 4 days