Does moss or lichen grow in your schoolyard or park? If so, you probably have water bears! These endearing and hardy micro-animals are fun to hunt for and easy to observe with a dissecting microscope at 40x magnification.
Also known as tardigrades, water bears resemble gummy bears with eight legs. Don’t let their cuteness fool you. Tardigrades are also tough. Dormant tardigrades, called tuns, can survive being frozen, boiled, and sent into space!
Back on Earth, scientists discovered that many tardigrades survived the ionizing radiation of space–and went on to lay eggs like this one, magnified hundreds of times in a scanning electron micrograph (SEM). Created by Eye of Science, these lovely, color-tinted SEMS are featured in Extreme Survivors: Animals That Time Forgot (Tilbury House Publishers).
Ready to go water bear hunting? Here are my tips from Extreme Survivors, with help from researcher Thomas C. Boothby, founder of the International Society of Tardigrade Hunters.
1. Collect small clumps of moss and lichen and put them in an envelope labeled with the location.
2. Soak the moss overnight or for a few days in distilled water or bottled water in a petri dish. Don’t use tap water, which may contain chlorine that can kill tardigrades.
3. Swish the moss in the petri dish and remove the moss.
4. Put the dish on a piece of black paper under a dissecting microscope. Shine a flashlight sideways across the dish. Tardigrades and other microscopic animals will glow against the black background.
5. When you’re done observing, release the water bears and other tiny creatures by pouring the water and placing the moss back where you found it.
You can read about my “tardi-party” here.
It can take a few tries to find water bears. If you’re short on time, I recommend this video, which I often share with students on my school visits as a fun nonfiction writing prompt.
You’ll find loads of tardigrade resources for teachers at Carleton College’s Science Education Resource Center.
Every time I walk by patch of moss like this one near my home in Maine, I like to imagine all the tardigrades, mites, nematodes, and other cool, tiny critters going about their mysterious business.
I hope you and your students have as much fun observing these ancient animals as I have, and I’d love to hear about your adventures!
Tardigrade photo by Peter Von Bagh on flickr, creative commons.