Sea Monkeys is the brand name for a hybrid-species of brine shrimp (a type of fairy shrimp which are not true shrimp). The term "Sea-Monkeys" is a trademark used to sell them as a novelty pet in comic books, etc., however brine shrimp originate in salt lakes and evaporation flats – not the sea.
The main characteristic that allowed un-hatched "Sea-Monkeys" to be cheaply packaged, shipped, and handled is that in easily prepared environments, they enter cryptobiosis, a natural state of suspended animation. When released into their aquarium they leave this state and smash through their inner shell walls. Sea-Monkeys can reproduce both sexually (requiring a male and a female) and asexually. When the eggs are produced, there are usually fewer males than females, probably because they are not essential for reproduction. Females stop reproducing with the males when the males are too few.
They were first bred at the New York Ocean Science Laboratories for their larger size and longer lifespan, making them more suitable as pets than the original breed of brine shrimp. Advertisements for Sea-Monkeys were widespread in comics in the 1970s, but the ads featuring drawings of smiling humanoid creatures, bore little resemblance to actual brine shrimp, so a disclaimer stated that, "Caricatures shown not intended to depict Artemia." Sea-Monkeys have a biological life cycle of one year, but thanks to their ability to enter cryptobiosis, a Sea-Monkey colony could sustain itself for two years.
A television program, The Amazing Live Sea Monkeys, based on the comic book advertisements of the 1970s, was produced in 1992.