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Experiment Idea: How To Observe Tardigrades, the Microscope World’s "Water Bear"

Tardigrades, also called water bears or moss piglets, are the stuffies of the microscopic world. Kids love them because they're so adorable. Even better, they're almost everywhere, and you don't need any expensive equipment or specialized knowledge to find and examine them. You can use any of IQCREW's microscopes to do your own tardigrade experiments. 

All About Tardigrades

Tardigrades are among the hardiest species in the world. They have been found in every biome on Earth, from the antarctic to the rain forest and from mountain tops to the bottom of the sea. Water bears can go dormant in hostile environments and have survived in the following conditions: 

  • Extreme pressure, both high and low
  • Radiation
  • Dehydration
  • Starvation
  • Extreme temperatures, both high and low
  • Outer space 
  • Lack of air

Although they can survive harsh conditions, tardigrades aren't immortal. Their normal lifespan is around 2 1/2 years, but they can survive for decades in their dormant state. 

Tardigrades grow to about 0.5 mm in length, which means they're ideal for a fun kid's microscope experiment. Their bodies are short and plump, with four pairs of legs that end in claw-like projections. They're easy to find in backyards in leaf litter, lichens, and mosses. 

How To Find Tardigrades

You'll need some patience to find your first tardigrade but you'll soon develop an eye for them. If your children are young or impatient, you might want to do the preliminary work beforehand so they don't get frustrated. You'll need a few basic supplies that you probably already have on hand to collect the water bears: 

  • Small bowls
  • A butter knife, tweezers, or forceps
  • A small mesh strainer, such as a drain liner, a tea strainer, or a flour sifter
  • Facial tissues
  • Small pipettes or a bulb medicine dropper
  • Slides and slide covers or a petri dish or a jar lid
  • Microscope

Tardigrades are called moss piglets because they're frequently found in moss, so that's a great place to start looking for them. You can also check in lichen, which may contain less dirt and be easier to shift through. Use your butter knife to scoop some quarter-sized samples of moss and lichen in different bowls. Your kids will probably love to help with this step. Once you have your samples, head home and take the following steps: 

  • Put your mesh strainer inside of a small bowl (one for each sample you collected)
  • Line the strainer with several layers of tissues
  • Place one of your samples on each strainer 
  • Pour distilled water over the moss or lichen until it reaches the level of the bottom of the moss
  • When the bottom layer of the moss or lichen is touching the water, leave it to sit overnight

In the morning, you can take off the strainer with the moss or lichen and tissues. You'll be left with a bowl of water and the tardigrades will be activated and at the bottom of the bowl. Use the pipette to remove some of the water from the bottom of the bowl to the jar lid, petri dish, or slide. If you don't have any type of pipette, carefully pour off the top of the water, being careful not to disturb the bottom layer. 

How To View Tardigrades

Now it's time for your tardigrade hunt! Take your water sample, either in a slide, a petri dish, or a jar lid, and examine it under the microscope to see what you can find. If you're using slides, you may need to prepare quite a few before you find a water bear. You may find other microbes before you find a tardigrade. Don't get discouraged. That's part of the fun. There are many microbes that are active in moss. Nematodes look like little worms and are fun to watch. 

When you're trying to figure out if you've found a nematode or a water bear, look for feet. Nematodes won't have any, while tardigrades will have stubby little feet with claws on the end. Nematodes are more common than tardigrades, so you'll probably find more of them. Water bears are rare enough to be exciting to discover but still common enough that you can find them a bit of effort. 

Tardigrade Experiments

Tardigrades are fun to watch, but you can also do some fun kids' experiments with them. You can try letting them dehydrate and then rehydrate them to check their survivability rate. You can also freeze them and then thaw them to see how many survive. 

This is a great opportunity to introduce your kids to a science lab notebook. Younger children can simply draw what they see, but older children can include charts and graphs of their results. 

You'll be in good company if you do science experiments with tardigrades. NASA sent water bears into space to try to identify the genes that are responsible for helping them survive such harsh conditions. Tardigrades have been crash-landed on the moon, shot out of a gun, and may have even entered a quantum state. 

Other Microscope Experiments

Tardigrades are just the beginning of what's possible to discover with microscopes. Even environments that look sterile and barren are teeming with microscopic life. Start by examining ordinary household items under your microscope. You can buy complete kits that include prepared and blank slides for your children to use in their experiments. The following materials are fun to look at under the microscope: 

  • Onion skin
  • Scrapings from mushrooms
  • Thin leaves
  • Insect parts
  • Cheek cells
  • Mold
  • Pond water
  • Pollen
  • Soap foam
  • Egg membrane

Most of these items can be simply placed under the microscope for examination. However, you can also introduce your kids to preparing slides using the following techniques: 

Wet mount

Wet mounts are used for living things or anything wet. You simply put a drop of water containing the specimen on a slide and top it with a coverslip. You can use flat slides or slides that come with a small indention in them for wet mounts. 

Dry mount

Dry mount slides are used without water. The specimen is placed directly on the slide, either with or without a coverslip. Some specimens may be too thick for a coverslip. 

Encouraging a Love of Science

Whether you're helping your child with a science fair project or just hoping to encourage a love of STEM (science, technology, engineering, and math), microscopes open up a whole new world to explore. You can show your children how exciting science can be by helping them investigate the world around them using all-in-one kits. If your kids want to dive deeper into microscopy, you can look into joining your local Microscopy Society. By fostering a love of science while they're young, you'll be setting them up for a lifetime of success.