Males differ from females by having the second antennae markedly enlarged, and modified into clasping organs used in mating. Adult female brine shrimp ovulate approximately every 140 hours. In favourable conditions, the female brine shrimp can produce eggs that almost immediately hatch. While in extreme conditions, such as low oxygen level or salinity above 150 ‰, female brine shrimp produce eggs with a chorion coating which has a brown colour. These eggs, also known as cysts, are metabolically inactive and can remain in total stasis for two years while in dry oxygen - free conditions, even at temperatures below freezing. This characteristic is called cryptobiosis, meaning "hidden life ''. While in cryptobiosis, brine shrimp eggs can survive temperatures of liquid air (− 190 ° C or − 310 ° F) and a small percentage can survive above boiling temperature (105 ° C or 221 ° F) for up to two hours. Once placed in briny (salt) water, the eggs hatch within a few hours. The nauplius larvae are less than 0.4 mm in length when they first hatch. Brine shrimp have a biological life cycle of one year.
when do brine shrimp produce eggs versus live birth
every 140 hours