Featured Creature: Tardigrade

Photo: Shuttershock

What creature can survive outer space, extreme temperatures, water scarcity, and even mass extinctions? 


Photo: Shuttershock

These ancient beings, which have existed on earth for over 500 million years, are hardier than even the infamously indestructible cockroach. 

Known as “water bears” or “moss piglets,” these microscopic creatures can be quite cute. Tardigrades actually make up their own phylum, a broad category of taxonomy like mollusks or sponges. Within this phylum, there are around 1300 species of tardigrades, and they are plentiful.

Tardigrades live in just about every corner of the earth. They like watery places, like bodies of freshwater, mossy areas (hence the term “moss piglets”), and the sediment of streams and oceans, but they’ve been found in more extreme locations, from geothermal hot springs to the Mariana Trench.  

Though there are plenty of them, these “micro-animals” are tiny, ranging from 0.05 mm to a little over a millimeter, so they can only be seen under a microscope. However, if you have a body of water, you can trust that there are Tardigrades nearby! 

What makes Tardigrades so hardy?

Tardigrades are famous for their survivability. They swim about, finding bacteria, plants, or smaller tardigrades to eat. They use their sharp claws to puncture cell walls and suck out nutrient rich fluids from their food of choice. Delicious! Just like with their habitat, tardigrades are not picky about their food, allowing them to proliferate. 

Besides having needs that are easy to meet, tardigrades have a few tricks up their sleeve to get by in extreme events. They can withstand extreme temperatures and pressures and the absence of oxygen. Though new research has indicated limits to their ability to withstand high heat, tardigrades have been shown to endure extreme cold, protect their cells against freezing, and live under intense pressure. They can even survive the vacuum of space and its harsh radiation.

Tardigrades do this by entering an extreme sort of hibernation – they undergo “cryptobiosis” (a state where nearly all metabolic function stops), expelling water from their bodies and curling up into dormant balls called “tuns” that are able to withstand the harshest conditions. In tun state, they experience about 0.01% of their usual metabolic function, and in this stasis, they do not need water or its oxygen to survive. They can stay like this for decades until conditions become more hospitable.

In most disastrous events that could wipe out humanity and most other living things on Earth, tardigrades have an edge in surviving. Scientists have modeled such improbable scenarios, including major changes to the biosphere, asteroid impacts, and the resulting conditions that organisms would have to contend with, and found that tardigrades could theoretically survive most of these doomsday scenarios. If these little guys had a slogan, it might be “Life goes on!”

Check out this neat animated video on the tardigrade’s remarkable resilience: Here!

Are tardigrades extremophiles?

Extremophiles are species that adapt to environments with, well, extreme conditions, like very high or low temperatures, high pressure, high acidity, or low oxygen levels. Some species of bacteria are extremophiles, thriving in these conditions that would kill off most other living things. Tardigrades, in contrast, prefer a regular mossy stream or riverbed, and so despite their ability to survive and get by in extreme environments, they wouldn’t be called extremophiles. They are, however, extremely cool!

While tardigrades may not be the most popular creatures, they deserve a lot of recognition. They show just how resilient life can be.