Sea monkeys are actually a hybrid type of aquatic creature known as brine shrimp. The brine shrimp known as sea monkeys have been bred to live longer lives in the home aquarium. Sea monkeys are small creatures, growing only between 1/2 to 3/4 inch in length. This makes telling the gender of the sea monkeys a bit of a challenge. Some people may believe that there is no way to tell apart males and females of a small shrimp. However, there are actually several ways that you can determine the gender of your tiny pets.
Compare the sea monkeys’ sizes, looking at all the sea monkeys as a group. Male sea monkeys are generally slightly smaller or shorter than the females.
Look at the sea monkey’s middle. Female sea monkeys always have egg sacks, circular in shape, which are clearly visible at about the midpoint of their bodies. These sacks will be white in color if the female is not carrying any eggs. If the female is carrying eggs, the sack will look to be brownish or yellowish. If you hold a magnifying glass up to the sea monkey, you may be able to see individual eggs. If you don’t see an egg sack, the sea monkey is most likely a male.
Look again at the sea monkey’s middle region, just past the bulk of its main body --the thorax -- if you did not see an egg sack on prior inspection. Since this may mean your sea monkey is a male, you can look for the male penes, which are tubular in shape. The penes are used for reproduction. Although they are visible when they are retracted, the penes can also be viewed when they are extended. When extended, the penes may stretch to more than four times their retracted length.
Look at the head area of the sea monkey. All sea monkeys and brine shrimp have two sets of antennas on their heads. In females, the first set is thick and short, while the second set is small all around. In males, the first antenna set is much like the females’, although it may be slightly thinner. However, the males’ second set of antenna differ greatly from the females’. The males’ second antenna are long and thick. They look something like large claws growing from their heads. These modified antenna are known as claspers or antlers. These claspers are what the males uses to grasp the female during spawning.