What Type of Animal Is a Sea Monkey?

Sea monkeys are a market name for the Artemia saline brine shrimp. Their biology, adaptation and nutrient value make them a marketing marvel. The sea monkeys eggs can lie dormant for years until rejuvenated in salt water. In 1956 Harold von Braunhut marketed the eggs as a kid's toy. He concocted a chemical recipe that turned ordinary tap water into a thriving environment and then sold the inactive eggs to kids via comic book ads. Sea monkeys are also harvested to feed shellfish and finned fish juveniles in commercial hatcheries.

  1. Biology

    • Sea monkeys eat microscopic phytoplankton in the wild.

      Sea monkeys are tiny transparent crustaceans and are white, red, pink, green and blue. They live in warm, salty pools and streams with partial sunlight. Adults have 11 pairs of hairy appendages. These filter algae, yeast and bacterial micronutrients toward their mouths and enable them to paddle through the water. Attached to the appendages are gills for breathing. Females lay eggs called cysts that contain trehalose, a gel-like simple sugar that substitutes for water if cyst cells dehydrate. Trehalose keeps cells safe from extreme weather and enables cysts to survive years without water, because it protects dormant cells from lethal damage. Adults mature in about five weeks and can live about four months.

    Sexual Characteristics

    • Mono Lake in California is a breeding ground for the brine shrimp.

      Primitive asexual Artemia species coexist with modern bisexual species. Female asexuals can flourish and produce new generations with no male fertilization. In bisexual species, a male must fertilize a female egg pouch to generate new cysts. Males use their mandibles to clasp females to mate with and fertilize them. Water temperature and salinity decide whether a female spawns live embryos or lays dormant cysts. Environments with proper saline, oxygen, pH and light rehydrate cysts, which develop into embryos called nauplii. When embryos split, free-swimming nauplii emerge. Nauplii shed their outer shells and grow new exoskeletons about 15 times before maturity.

    Unique Features

    • The baby nauplius is born with one eye but grows two compound eyes as it matures. Cysts can remain inactive for as long as 25 years and then rehydrate in salt water without inner or outer structural damage. Brine shrimp are light-sensitive; they swarm toward light and darkness makes them still until they find light, which makes them dance frantically. A cluster of dormant cysts looks like brown crystals; when salt water is added, the "magical" dust suddenly "comes alive" as dark orange nauplii begin swimming with jerky moves.

    Aquaculture Industry

    • The sea monkey is invaluable to the aquaculture industry because dried cysts can sit in a cool, dry, sealed container for many months. Utah's Great Salt Lake harvests 90 percent of the world's cyst supply. Cysts sell for $20 to $30 a pound to home aquarium enthusiasts, aquaculture systems and research laboratories. Nauplii provide the perfect energy and nutrition for thriving young fish and shellfish larvae. Dried cysts are actually inactive embryos (not eggs) that stay dormant as long as they remain dry.