Maybe you have tried to find tardigrades before, but without any luck. Maybe you have found a few by “accident”. Or maybe you have never tried, and just want to get it right the first time. No matter what, the method I describe here is both an easy, fast and consistent way of finding tardigrades, and more than one!
All you need is:
- A microscope
- A plastic container
- Some water (preferably bottled water/spring water but tap water works as well)
- A strainer (not a must have)
- A petri dish
Tardigrades are without a doubt one of the most exciting microorganisms to find under the microscope, especially if you are searching for them specifically. The tardigrade is one of the smallest animals on the planet and finding them might sound difficult but with this method it should be rather easy! Tardigrades live on all continents in all environments, so if you have a microscope at hand you are all set no matter where you live. Now you just need the right sample and prepare it in the right way, and this is what I’m here for. To give you a few tips and tricks, that should help you find multiple of the little bastards in the first try, hopefully.
Even though the tardigrades live all over the planet, they can sometimes be a bit difficult to find if you don’t know where or how to look. Another name for the tardigrade is a moss piglet. This is because tardigrades are often found in moss. And even though it is possible to find the animal in moss, it is not the best way.
What I find to work the best is to take a small plastic container, find a tree with some lichen and scrape the tree with the container to collect some of the lichen. To maximize your chances of finding tardigrades and even entirely different species, you can sample a few trees into the same container (preferably different kinds of trees. And not trees standing right next to each other). When I go sampling for tardigrades, I usually end up with a total of around 2-5 tablespoons (20-50 mL) of sample in a container.
When you got your sample, you need to hydrate it to get the tardigrades out of cryptobiosis, which is a form of hibernation. This should ideally be done with bottled water/spring water, because tap water contains chlorine and other chemicals that will kill some of the microorganisms in the sample. But tap water will work as well. You want to use enough water to cover the sample, roughly the same amount of water as sample. Then you shake or stir your sample for a minute or two to make sure everything gets hydrated and to knock the tardigrades from the lichen into the water. If your container has a lid, just put that on and give it a gentle shake for a minute.
Now you take your hydrated sample and pour it through a strainer into a petri dish, to filter all the big chunks out. If you aren’t afraid of getting you hands dirty, squeeze the wet lichen in the strainer to flush some more tardigrades out (or use a spoon). If you don’t have a strainer, just pour the water directly into the petri dish, but hold back the lichen with your fingers.
The only thing left to do now is to take the petri dish, put it under the microscope and let the search begin. The tardigrades will slowly get out of the cryptobiosis over the next 15 minutes. So, if you don’t see any at first, have patience. The 4X objective (40X total magnification) is enough to see the tardigrades, and I would recommend you start your search with that. When you find a tardigrade, you can switch to the 10X objective to get a closer look. Unfortunately, when you are using a regular microscope and a petri dish with water, you can’t get closer than the 10X objective because the bigger objectives will crash into the water. If you want an even closer look, you have to either transfer the tardigrade to a microscope slide or search the sample a few drops at a time on a microscope slide, remember a coverslip to avoid getting water on your objective.
Now you should be all set for tardigrade hunting. I hope this was helpful. If this method works for you and you find some tardigrades, I would love to see them. You can use the tag #mymicroscopictardigrade on Instagram or mention @my.microscopic.world and I will be sure to check them out!
Here are some links to some cheap petri dishes and sample tubes like the ones I use I found on amazon (these are affiliate links which means I get a small commission if you choose to buy anything. But dont worry, your price doesn’t change).