Brine shrimp are tiny crustaceans that live in saltwater lakes and oceans. They are a major food source for other fish and water-dwelling birds, and have a unique life process that allows them to go into a dormant state when dry. The dried form of these creatures is commonly sold as food for aquarium fish as well as under the name of sea monkeys. Brine shrimp can survive in very polluted waters and can actually help cleanse the water by recycling some of the chemicals in it.
Adults are about half an inch (1 cm) in length. The body of the brine shrimp is naturally transparent, but when it consumes a regular diet of a particular color of algae, it can begin to turn that color, much like the effect shrimp have on flamingos. Each shrimp has 22 microscopic fins that propel it through the water, and males have two larger appendages at the front of the body. They feed on microscopic bacteria and single-celled organisms.
The only water that the brine shrimp can survive in is extremely salty, and this limits the places where it occurs in nature. The species was first discovered in England in ponds with an incredibly high salt content; since then, it has been studied extensively in the United States' Great Salt Lake. Here, it was found that in spite of the shrimp-like appearance that gave the creatures their name, they are more closely related to shellfish like lobster. It was also discovered that they feed on chemicals such as phosphorus, which can enter a lake's ecosystem through pollutants like chemical fertilizers.
The life cycle of brine shrimp is a unique one that allows them to thrive in difficult conditions. The brine shrimp is capable of a process called parthenogenesis, in which the female develops, lays, and fertilizes eggs called cysts without the assistance of a male. When the eggs are laid, they are covered in a protective coating, which will only dissolve when conditions are right for the larvae to hatch and grow. If conditions are not right, the eggs will remain dormant.
This ability makes brine shrimp a popular choice for fish food in home saltwater aquariums. Eggs can be dried and sold in powder form, hatch once introduced to the tank environment, and be eaten fresh by the fish. Brine shrimp are also sold in containers under the name of sea monkey.