Conservation of our planet’s botanical resources and ecosystems

Questions about Tardigrades from the Higgins Family

The Higgins family e-mailed us to ask some questions about Tardigrades. Alex Young, a recent graduate at Lewis & Clark College who discovered a new species of tardigrade in 2014, provided some answers to these thoughtful questions.

Below are the questions submitted by the Higgins family and the responses from Alex Young.

1. Do we know WHAT allows them to survive in space? If so, can this be manipulated to benefit us?

I’ll begin with talking about an ability of most tardigrade species, which is the ability to enter a state of suspended animation. Tardigrades can only be active when they are surrounded by a film of water. They only require a small amount (think the vapor of a cloud, or a moist cushion of moss). If the environment they exist in becomes dry, they expel 98% of their water content, and shrivel up into a “tun”. While in this tun state,nothing inside the tardigrade moves, it has no metabolism, every life process is halted. It is in this tun state that they are able to exist in a wide range of environmental conditions. When water returns to their environment, they re-hydrate, and begin to walk around and go about their tardigrade life all the same.

but just HOW do they do this? I can assure you that people are looking into it, and it involves an in-depth study of tardigrade cells and the cellular mechanics involved in entering into the tun state. Also known as cryptobiosis. Some thought is the trehalose sugar that is found in the membrane of tardigrade cells. However, recently it was found that a glass covering may hold the key to their extraordinary ability.

– Side note to the vacuum of space: The amount of radiation that an organism would be exposed to in outer space (above a planetary atmosphere) is incredibly high. Also temperatures can fluxuate between extremely hot, to extremely cold in a matter of seconds depending if the object is exposed to solar radiation or shielded from it by a planet.

– side note about the tardigrades in space research- The whole story about the experiment is that they sent up shrivelled tardigrades (in the tun state) and exposed them to the vacuum. Then sucked them back in. brought them back to earth. rehydrated them. They Lived! then reproduced and made offspring. The space tardigrade offspring were completely viable, and functioned normally which is quite a feat!

2. What would happen if some of these Tardigrades where injected into someones blood stream?

There are two components that come into play for this question. One is the physical size of a tardigrade. About 1 mm long, and .4 mm wide on average. There are certainly human blood vessels that are wide than one millimeter (Like major blood vessels immediately surrounding the heart) but there are many more blood vessels that are smaller than 1 mm. A tardigrade would cause a physical blockage, and would be a considerable problem.

The second component is what would happen to the tardigrade surrounded by red and white blood cells in a blood vessel. The human body does a very good job of keeping “outside” out, and “inside” in. The body does this with its immune system that is incredibly good at deciding what particulate is good, and should be left alone to circulate in the human body. It is also good at detecting what is “foreign” or bad. the human immune system would most likely attach the tardigrade, surround it in white blood cells, and send it to the proteosome, a cellular machine that degrades proteins into simpler units.

3. People always said roaches will live the longest if something bad happened to earth. Would that title now be held by Tardigrades? [Ignoring the differences between the two creatures]

I think its safe to say that tardigrades will out-exist most organisms, as they have a pretty long track record already. They have survived 5 mass extinctions, and are evolutionarily quite old. Roaches are perhaps a more visible animal to humans, and thus have received the title, but it really comes down to whether or not an organism could have access to the resources it requires to survive and reproduce. Tardigrades eat free living microbes like algae and bacteria. I think it is safe to say that tardigrades will last longer than roaches if something bad happened on earth. However, the true ticket would be the microbial life. Microbes are powerful, and they rule this earth.

4. Do Tardigrades benefit ecosystems? Why couldn’t we take a few billion of them to mars and turn them lose? see if they start some kind of growth?

This is an intriguing question, and one that I think about a lot.

“Benefit” is a somewhat tricky word. Recently I was introduced to a concept of how to think about ecosystems, and their function. Similar to legs on a table, each species can be thought of as a leg that supports the table top. If you were to lose a leg of that table, the whole table top becomes less secure, less stable. However, we arent sure how much each “leg” of the table supports, or even how many legs are under this hypothetical table. Ecosystems are incredible complex, and their functioning is what provides all life with the resources needed to live! Tardigrades exist in ecosystems (more than one in fact, from the deep oceans, to wetlands to the top of icy mountains!) and as such, they have some impact on the space they inhabit. However small (or BIG) of an impact tardigrades have on ecosystems I would think that removing them from ecosystems would not be a good idea.

Shipping them to Mars? that is a neat idea. Wonder if they could do it? However, when talking about other planets, it is necessary to think about the biological contamination that could occur, which is something that NASA tries very hard to accomplish. They sterilize everything that they send into space, however, even satellites that do not have any humans on them are prone to being habitat for microbes, and it is somewhat of an issue you dont hear about often. Fungal molds have been found in space craft that have been circling around for 10 to 15 years, and it causes problems when seals are degraded because of fungal mold growing and disturbing what was meant to stay exactly the same.