Ant farms and Sea Monkeys have been around for decades, and it’s little wonder that they’ve been so popular. These educational kits captivate children of all ages, enticing them to care for and watch the little creatures as they grow and carry out their intricate lives, lives that would otherwise be hidden or probably go unnoticed by us. They’re a stimulating introduction to the field of biology, or even fun—great gift!—for the experienced biologist.
So with spring finally sprung and summer break waiting just over the horizon, now’s a great time to look into some of the many educational biology kits out there. This installment of Biology Bytes will focus on the critters that make the classic ant farm and Sea Monkey kits possible. Next time, we’ll explore many other kinds of temporary “pets” available today—several of which can be found in most backyards—for the experienced or burgeoning biologist in all of us.
Ant Farms Ant farms, also known as “formicariums,” have been around for over half a century, and their great popularity highlights just how interested people are in watching the life of tiny, hard-working insects. Ant farms are typically a thin box with sides of transparent glass or plastic, filled mostly with dirt, allowing viewers to watch how ants work together to industriously build intricate tunnels through the dirt, store seeds they’ve gathered into different underground compartments, and even relocate the bodies of ants that have died. More recently, ant farms filled with a nontoxic, transparent gel instead of dirt have become widely popular as they allow a person to better see what’s going on in the “farm.”
Although ant habitats have caught the public spotlight only over the last century, ants themselves evolved from a wasp-like ancestor some 120 million years, making them quite a bit older than the dinosaurs. Ants still belong to the group that includes wasps and bees (the order Hymenoptera), though they’ve since evolved into thousands of different species. Most ants sold for ant farms are red harvester ants (Pogonomyrmex barbatus), which are from the Americas. They were named “harvester ants” because they love to gather and hoard great numbers of seeds, their primary food source. They can easily store thousands of seeds from over a hundred different plant species (mostly grasses) in their nests. These ants’ large size (about a quarter-inch long), combined with the fact that their food is easy to provide, makes them ideal for observing and keeping in an ant farm.
And there’s a great deal to observe in a natural harvester ant nest! All the chores are divided up among the ants, and they work together to ensure the nest thrives. Scouts are the first ants to leave the nest each morning, and their trails to food are followed by worker ants that collect the food. “Midden” ants keep nests clean, moving trash (such as dead ants and other rubbish) to specific chambers in the nests. Most of the ants in natural nests are workers, which are sterile female ants. There’s usually only one queen ant per nest, and she is responsible for creating all of the other ants.
While most of the ants the queen produces are sterile workers, sometimes she makes male or female ants that are sexually active. On certain days, based on the season and local weather, these ants will fly from their nests to mate with ants from other nests (amazingly meeting at the same place year after year). After mating, the males die, and the young queen ants will never mate again; each would now be storing thousands of sperm in a special organ inside of herself, and those sperm can survive for up to 40 years, all while she continues to lay eggs.
The young queens quickly set off to find suitable locations for their nests and start digging. Then each queen will lay her first clutch of 20 to 30 tiny, pearly white eggs. The larvae that hatch from these eggs will develop into adult workers after five to six weeks, at which point they’ll start taking care of the queen and her subsequent eggs. But it’s hard making a go of a new nest: Only about one out of 1,000 females that mate will have a nest after the first season.
The red harvester ants sold for ant farms in the U.S. are sterile worker ants. It’s illegal to sell queen ants in the U.S. because they can make new nests if they get loose, which is part of why there are about 150 ant species living in parts of the world that they don’t naturally live in. But, if you want to see a full nest in action, there are ways of catching queen ants; just don’t relocate them and be careful.
Speaking of being careful, a word of caution when checking out the ants in your ant farm, as red harvester ants have a notoriously painful sting. Although the sting of some wasps is said to be worse, a sting from a red harvester ant can linger for a day or longer. Amazingly, this ant venom contains enzymes that break down fat proteins, blood cells, and other molecules in your cells! But these little seed-gatherers don’t use their sting to kill live animals; they mostly use it in defense.
Despite their mostly vegetarian diet, they’re not too refined to overlook snacking on some small animal carcasses or dead bugs such as butterflies, spiders, worms, millipedes, other ants, and more. All of this industrious digging, harvesting, and scrounging helps the environment, too: Ants not only aerate the soil with their tunnels, but they help recycle nutrients in the dirt and pollinate plants.
A variety of ant farms can be purchased online at Amazon.com, or at many other online Web sites, such as this great biology Web site for kids of all ages, Insect Lore, or the Carolina Biological Supply Company.
Sea Monkeys Brine shrimp, also known as Sea Monkeys, have also been extremely popular if short-lived “pets” for decades. Brine shrimp (which belong to the genus Artemia) are small, ancient crustaceans, putting them in the same group as crabs, lobsters, other shrimp, and crayfish. These tiny shrimp, attaining lengths of only one-third to two-thirds of an inch as adults, seem to come to life from grains of sand.
The ability of brine-shrimp eggs to withstand extreme conditions has made them ideal for selling commercially. They can be gathered in large quantities and stored for long periods of time, then they spring to life when needed. Brine shrimp were originally used in the 1930s as an easy food source for baby fish, and aquarium hobbyists still buy brine shrimp in pet stores today to feed picky fish. Since the 1960s, brine-shrimp eggs have been cleverly packaged as “Sea Monkeys” and sold as kids’ pets or as novelties. Such kits not only include eggs, but also microscopic food for the brine shrimp. (In the wild they eat tiny algae, but cultured ones can eat yeast, egg-yolk proteins, wheat flour, and more.) And, of course, salt is essential for brine shrimp.
Most brine-shrimp eggs were originally harvested from the Great Salt Lake in Utah, where they’re one of the few multicellular organisms that enjoy that kind of super salty environment. Today, there are about 500 natural salty bodies of water worldwide from which brine shrimp are commercially harvested. Because they live in extremely salty, or hypersaline, environments with few predators, brine shrimp don’t really have natural defenses, which is why they don’t live in the open ocean. Brine shrimp can tolerate water that has a lot more, or a lot less, salt than is in normal sea water, even amazingly surviving in water that is 50 percent salt. This is a saturated solution! But they can’t survive in fresh water for over an hour. Astoundingly adaptive, they can tolerate a range of oxygen levels and temperatures, living in places as cold as Tibet and Siberia. They’ve done so well for themselves that researchers think they essentially haven’t changed over the last 100 million years.
Part of their great success is due to their super durable eggs (which are technically called cysts). The brine-shrimp lifecycle is about a year long: The cysts are usually laid in fall and hatch the following spring, repopulating a lake after winter has passed. But a harsh winter is the very least of what they can survive. The dormant cyst state (also known as diapause) is one of the most resilient life stages known, and brine-shrimp cysts can survive in this stage for two years. They can even, amazingly, be completely dried out (not a feat humans can come close to accomplishing, being about 60 percent water) and exposed to an oxygen-free or below-freezing environment and still be fine. Some can even survive temperatures above 200 degrees Fahrenheit for a couple hours. But when they’re put in some salty water with normal oxygen levels and temperatures, these cysts hatch within a few hours.
The durability of these cysts, and the relatively short life span of the shrimp, make brine shrimp very appealing creatures to investigate. Researchers have even hatched brine shrimp in outer space.
Triops Triops, also known as the “dinosaur shrimp” or tadpole shrimp, are also sold as educational “pets,” and while they haven’t been on the market as long as ant farms and Sea Monkeys, they’re quickly becoming more popular. Like brine shrimp, Triops are crustaceans, but Triops get much bigger than brine shrimp, easily reaching two-and-a-half inches long. Triops basically look like a little horseshoe crab, with a characteristic shield-like carapace (a hard outer covering, like what turtles have) and a long “tail.” They have three little eyes, which is how they got their name (from the Greek “tria” for three and “ops” for eyes). These are truly ancient animals; modern Triops have changed little in the last 200 million years, which is why they’re nicknamed “living fossils” (for reference, most dinosaurs went extinct about 65 million years ago).
And what has made Triops so successful for all these years? They’ve become extremely well-adapted to living in little temporary ponds (also known as vernal pools). Usually during winter and spring, rain fills these pools and the Triops eggs hatch. The Triops can grow to two inches long in just a few weeks, molting their exoskeleton several times in the process. Since they’re omnivores, it isn’t hard for them to find food; they eat most things, from algae to brine shrimp and insects that they hunt down, and more, sometimes even eating their own siblings, all while swirling the bits of food into their mouth using their many little appendages. After quickly reaching maturity, they lay eggs. They die when the water disappears, but can potentially live for about 50 to 90 days if water remains. The eggs remain in the dirt after the pond’s dried up, waiting for the next rain.
Like brine shrimp, the eggs of the Triops can endure harsh conditions and wait a long time before they spring to life in their temporary habitat, but in some ways the Triops eggs are even more impressive. Triops eggs can withstand freezing and temperatures over 200 degrees Fahrenheit for over half a day, and can normally survive in their dormant state for up to 20 years. But because they’re so adapted to living in temporary water, the eggs need to completely dry out before they can hatch; they won’t hatch in a permanent body of water, but have to wait until the water leaves and returns. Their amazing lifecycle makes Triops one of the few species adapted to these short-lived pools, and a true delight to watch grow and change over the span of several weeks. Moreover, understanding how the eggs’ prolonged dormant state is achieved may help researchers better understand how we can control the unwanted growth of our own cells, such as in cancer.
Next Time Tune in to Biology Bytes in two weeks for a discussion of live biology kits beyond ant farms and Sea Monkeys, when we look at silkworms, earthworms, caterpillars, fascinating plants, and much more, including some good tools to equip your budding biologist for exploring hidden life in the backyard!
For more on ant farms, Sea Monkeys, and triops, see the books The World of the Harvester Ants by Stephen Welton Taber, Urban Ants of North America and Europe by John Klotz, Laurel Hansen, Reiner Pospischil, and Michael Rust, Artemia: Basic and Applied Biology by T. J. Abatzopoulos, J. A. Beardmore, J. S. Clegg, and P. Sorgeloos, Triops – A Very Unusual Creature by Helen Pashley and Lori Adams, or Wikipedia’s articles on “Pogonomyrmex barbatus,” “Sea Monkeys,” or “Triops.”
Biology Bytes author Teisha Rowland is a science writer, blogger at All Things Stem Cell, and graduate student in molecular, cellular, and developmental biology at UCSB, where she studies stem cells. Send any ideas for future columns to her at firstname.lastname@example.org.