Morphology and life cycle
The adult Artemia is about 1cm long with a pair of stalked complex eyes, 11 pairs of thoracopods, sensory antennulae, and a linear digestive system. The male possesses a pair of the posterior penis, while the female has a conspicuous brood pouch located behind the thoracopods. Eggs grow in a pair of tubular ovaries situated in the abdomen (Van Stappen 41).
Normally, fertilized eggs grow into swimming nauplii following their release by the mother. However, in unfavorable conditions such as low O2 levels and high salinity, the embryo only grows up to the level of gastrula and gets cocooned and enters a state of dormancy prior to their release. Theoretically in all Artemia strains, females can switch in between oviparity and ovoviviparity mode of reproduction (Van Stappen 87).
In its natural habitat at the appropriate time, Artemisia lays biconcave-shaped cysts which float on the water surface to be washed ashore by waves and wind. The cyst is metabolically dormant and does not undergo further development in dry conditions. However, when they get immersed in seawater the cysts absorb water, attain a spherical shape and the embryo inside the cyst resumes its metabolism. In 20 hrs time, the shell burst releasing the embryo which hangs beneath the shell and the hatching membrane burst to release a free-swimming nauplius shortly (Van Stappen 43).
