Increased levels of the latter hygroscopic compound result in further water uptake by the
embryo. Consequently, the osmotic pressure inside the outer cuticular membrane builds up
continuously until a critical level is reached, which results in the breaking of the cyst
envelope, at which moment all the glycerol produced is released in the hatching medium. In
other words the metabolism in Artemia cysts prior to the breaking is a trehalose-glycerol
hyperosmotic regulatory system. This means that as salinity levels in the incubation medium
increase, higher concentrations of glycerol need to be built up in order to reach the critical
difference in osmotic pressure which will result in the shell bursting, and less energy
reserves will thus be left in the nauplius.
After breaking the embryo is in direct contact with the external medium through the hatching
membrane. An efficient ionic osmoregulatory system is now in effect, which can cope with a
big range of salinities, and the embryo differentiates into a moving nauplius larva. A hatching
enzyme, secreted in the head region of the nauplius, weakens the hatching membrane and
enables the nauplius to liberate itself into the hatching medium.