By using a simple Sea-Monkeys toy, students can unlock the secrets of cryptobiosis—the remarkable survival trick that lets tiny creatures spring back to life in extreme environments. Science communicator Ceana Priest uncovers how Sea-Monkeys can help develop scientific methods of observing and experiencing the natural world.
Sea-Monkeys are actually brine shrimp—tiny crustaceans from the Artemia family that live in salty lakes and ponds, including Lake Grassmere in Marlborough, which produces half the country’s salt by evaporating seawater. The water in these environments is so salty that brine shrimp and certain types of algae are often the only things living there.
What makes these critters even more interesting is their ability to survive extreme drought conditions through a process called cryptobiosis, which allows their eggs to completely dry out and stay dormant for months or even years before coming to ‘life’ when water returns.
History of Sea-Monkeys
This unusual survival strategy caught the attention of American inventor and showman Harold von Braunhut in 1957. He saw brine shrimp being sold as fish food and wondered if their life cycle could be turned into something educational for kids. With help from marine biologist Anthony D’Agostino, he developed a formula that included salts, water purifiers and food—everything the shrimp would need to survive once the eggs were added. The first version of the product was sold as Instant Life for 49 cents. A few years later, in 1962, it was rebranded as Sea-Monkeys—a name that sounded more exciting, especially to children seeing ads in comic books. The version sold in stores was reportedly a special hybrid strain, Artemia NYOS, named after the New York Ocean Science Laboratory, where it was allegedly developed.
Sea-Monkeys were intensely marketed as pets, particularly through comic books, throughout the 1960s and early 1970s. The marketing featured illustrations (below) by comic-book illustrator Joe Orlando depicting humanoid animals, which disappointed many buyers because the actual crustaceans looked very different.
Using the Sea-Monkeys’ kit
Inside the kit are three packets to set up the brine shrimp habitat, introduce dried-out brine shrimp eggs and food.
Stage 1: The water purifier packet
This first packet is crucial for setting up the ideal Sea-Monkeys’ environment.
What’s in the packet? The Water Purifier packet contains dormant cysts (the dried-out eggs), along with salt and conditioning agents.
Setting up the habitat: Brine shrimp naturally live in highly saline environments, such as salt lakes and temporary pools. The salts and conditioning agents in this packet help recreate their natural, very salty environment. This is vital for their survival and activation.
The science of survival – cryptobiosis
- Sea-Monkeys (brine shrimp) are remarkable because their eggs can survive extreme drought conditions through a process called cryptobiosis.
- Cryptobiosis is a state where an organism almost completely shuts down its metabolism to survive harsh conditions, acting like a temporary ‘pause button’ for life. Unlike hibernation, metabolism nearly ceases, allowing the eggs to remain alive but inactive for months or even years.
- Brine shrimp specifically use a form of cryptobiosis called anhydrobiosis, which allows them to lose up to 99% of their body water and enter a state of suspended animation when experiencing extreme water stress or desiccation (drying out). In this dried form, called a cyst, all visible signs of life stop.
- Molecular Protection: During anhydrobiosis, the organisms produce protective sugars, such as trehalose, which help stabilise proteins and cell membranes, preventing damage during desiccation. This also provides a significant energy source when the cysts rehydrate.
Key anhydrobiosis characteristics
- Metabolic depression/slowdown: Eggs stop all activity while dry.
- Reversibility: Once cysts are placed in salty water, they ‘come back to life’.
- Survival mechanism: Helps brine shrimp survive droughts and salty environments where water may disappear.
- Molecular protection: Special molecules protect the egg’s cells and proteins from damage.
Stage 2: The Instant Life Eggs Packet
After the initial setup, this packet adds more ‘life’ to the tank, triggering the next development phase.
What’s in the packet? This packet adds more eggs and nutrients, which are designed to trigger the hatching process.
- Once the cysts are placed in suitable salty water, they rapidly ‘come back to life’.
- Hatching begins within hours, releasing tiny nauplius larvae.
- Under ideal conditions, typically at 24–27°C (75–81°F), development happens quickly.
Early development and unique features
- Brine shrimp are born with one eye, a simple naupliar eye, which is common in many crustaceans at the larval stage and is retained into adulthood.
- As they develop, they grow two additional compound eyes, which provide enhanced visual perception as they mature.
- They respire (breathe) through their phyllopodia—feathery, leaf-like appendages that also help them move. These limbs beat in coordinated waves, allowing the shrimp to swim in a distinctive, undulating motion.
- Their forked tails, which curl upwards, have been described as vaguely ‘monkey-like,’ inspiring their popular name.
- Growth Rate: Sea-Monkeys reach maturity in about 8 days.
Stage 3: The Food Packet
As the Sea-Monkeys grow, providing them with the proper nourishment is key to their continued health and development.
What’s in the packet? The third packet includes food (mainly dried algae powder—often spirulina or chlorella) and a few more eggs, ensuring a constant supply of new brine shrimp.
- Diet and growth
- In their natural habitat, brine shrimp feed on specific types of algae. The food packet provides this essential diet.
- With proper nutrition, they can grow to be about 15 mm long.
- Life cycle and reproduction
- A full Sea-Monkey life cycle plays out over 8 to 10 weeks.
- While cryptobiosis is a survival strategy, brine shrimp also have five unique reproductive strategies:
- Pretermitted oviparity: Uses cryptobiosis for survival in drought conditions, where eggs are laid and remain dormant.
- Viviparity: The mother gives live birth to her young.
- Oviparity: The mother lays eggs that hatch outside her body.
- Ovoviviparity: Eggs develop and hatch inside the mother’s body, leading to live births.
- Necro ovoviviparity: Even if a pregnant female dies, the viable eggs she carries can continue to develop and hatch inside her, resulting in live births.
Beyond the kit: Amazing cryptobiosis and other survivors
Anhydrobiosis is only one type of cryptobiosis. Others include:
Cryobiosis (freezing survival): This occurs when organisms are exposed to freezing cold temperatures. They slow down their bodily functions to survive being frozen solid. One example is the mountain stone wētā (Hemideina maori), which lives in cold mountain areas. It can survive even if 80% of the water in its body freezes. The wētā makes special ‘antifreeze’ chemicals called cryoprotectants to protect its cells from damage. When the weather warms up, the wētā ‘wakes up’ and moves around again.
[Image: Frozen mountain stone wētā in the Southern Alps, New Zealand. Credit: Santanu123 CC BY 4.0]
Anoxybiosis (surviving without oxygen): Sometimes animals have to survive when there’s no oxygen at all. In anoxybiosis, they take in water and become stiff, stopping all their body functions until oxygen returns.
Osmobiosis (handling salty or sugary water): Osmobiosis happens when there’s a lot of salt or other dissolved particles in the water, making it hard to live there. Brine shrimp can pause their lives when the water gets too salty. They stop their metabolism and form protective eggs called cysts until conditions get better.
Chemobiosis (surviving poisonous conditions): Some tiny creatures called rotifers, which swim using little hairs called cilia, live near geothermal areas like Rotorua and Taupō where the water has toxic chemicals. They slow down their metabolism to survive the poisons.
Tardigrades | Tiny but mighty survivors
Another organism that uses cryptobiosis to survive is the tardigrades, also called water bears or moss pigs. These microscopic animals are known for their incredible toughness. Less than a millimetre long, they live all over the world, including New Zealand, where around 90 species have been found so far. They can handle extreme heat, freezing cold, radiation, and even the vacuum of space. Some have even been sent into orbit, exposed to solar radiation, and later brought back to life, healthy enough to have babies. A recent discovery in the Southern Alps revealed four new species crawling through solid ice on the Fox and Franz Josef glaciers, and in the Whataroa Valley, feeding on algae and thriving in the icy cold. When conditions get too dry or harsh, tardigrades curl into a dried-up ball called a tun and shut down almost all life processes. In this state, they can survive without food, water, or oxygen—sometimes for decades. These tiny creatures are living proof that size doesn’t matter when it comes to surviving the impossible.
Ngā kupu
mātanga pūtaiao: scientist
moana: sea, ocean, large lake. This is the source of the saltwater where the brine shrimp live.
moe hōtoke : to hibernate, hibernation
pūtaiao: science
rangahau: to seek, search out, pursue, research, investigate
Te Moana-nui-a-Kiwa: Pacific Ocean. Literally translates to ‘the great ocean of Kiwa’.
tote: salt, salted, to salt, add salt
wai māori: freshwater, mineral water
[Sourced from Te Aka Māori Dictionary]
Classroom questions and activities
Complete an observation log as the Sea-Monkeys grow. Download a written and visual blank PDF log.
Why don’t all animals have a pause button? Why do you think Sea-Monkeys can pause their life, but humans can’t?
What happens if the habitat changes? What might happen to the Sea-Monkeys if their water dries up or gets too dirty?
Cryptobiosis allows organisms to survive hard times—but only for a while. Everything on Earth needs a relatively stable habitat for long-term survive. What might be happening to the habitat on Earth? List three things that might impact human survival.
Further links
The Great Big Story | The Mad Genius Behind Sea-Monkeys [YouTube Video]
BBC Earth | Frozen wētā: The Insect That Freezes To Survive | Nature’s Biggest Beasts [YouTube Video]
Picocosmos | Life Cycle of Brine Shrimp | Brine Shrimp Microscopy [YouTube Video]