Brine Shrimp Lifecycle
The brine shrimp, Artemia,belongs to the phylum Arthropoda (joint-legged invertebrates), class Crustacea (shrimp, crab, lobster). There are several species of Artemia worldwide; Artemia franciscana is the species living in Great Salt Lake (and also in San Francisco Bay). Brine shrimp live in hypersaline lakes in which the salt content may be 25%, predators and competitors are few, and algal production is high. The life cycle of Artemia begins from a dormant cyst that contains an embryo in a suspended state of metabolism (known as diapause). The cysts are very hardy and may remain viable for many years if kept dry. Water-temperature and salinity changes in Great Salt Lake occur in about February and cause the cysts to rehydrate and open to release the first growth stage, known as a nauplius larva. Depending on the water temperature, the larvae remain in this stage for about 12 hours, subsisting on yolk reserves before molting to the second nauplius stage, which feeds on small algal cells and detritus using hair-like structures on the antennae known as setae
Although the cysts are very small (about 200 micrometers in diameter; 50 could fit on the head of a pin) at times they become so numerous that they form large red-brown streaks on the surface of the lake. Under optimum conditions of food supply and lack of stress from increasing salinity or decreasing dissolved oxygen, fertilized female shrimp may produce eggs that hatch soon after emerging from the ovisac to produce nauplius larvae, which is known as ovoviparous reproduction. If conditions are perfect, the female can live as long as 3 months and produce as many as 300 live nauplii or cysts every 4 days. However, the cold spring-time temperatures and variable food supply in Great Salt Lake usually limit the population to two or three generations per year.
The nauplii molt about 15 times before reaching adult size of about 10 millimeters in length. Adult male shrimp are easily identified by the large pair of "graspers" on the head end of the animal. These are modified antennae and are used to hold unto the female during mating. The population of Artemia franciscana in Great Salt Lake includes both males and females and reproduces sexually, but some species of Artemia exhibit parthenogenesis, a reproductive mode in which only females are present that give rise to young females in the absence of males. Adult shrimp feed primarily on phytoplankton (algae) suspended in the water but can also "graze" on benthic algae such as blue-greens or diatoms growing on the bottom of Great Salt Lake in shallow areas. They also may reprocess fecal pellets excreted earlier in the year when large numbers of phytoplankton present in their diet were incompletely processed. A recent study showed that the shrimp can graze on diatoms that colonize shrimp exoskeleton parts released from their many molts. As the food supply becomes exhausted, salinity increases, dissolved oxygen decreases, or a combination of these conditions occurs, the female shrimp switch from producing live young to producing cysts through oviparous reproduction. In Great Salt Lake, the adult shrimp typically die from lack of food or low temperature during December. Although, live brine shrimp have been observed in the lake at a water temperature of 3 degrees Celsius (37 degrees Fahrenheit), it is unlikely they can reproduce at that temperature. The cysts, which in Great Salt Lake are lighter than the lake water, float on the water surface where they may be harvested or may overwinter to form the source of shrimp for the following year.
Brine shrimp are also called "Sea Monkeys" and are raised in aquariums for their entertainment value.
You will finds links about Sea monkeys, Brine shrimp, Fairy Shrimp. You wil learn about raising brine shrimp and hatching brine shrimp and what is the brine shrimp life cycle