Thursday, April 23, 2015

Talkin' About Tardigrades

They are tiny. They are tenacious. They are tardigrades.

Even as a biology major in college, I didn't learn about these fascinating creatures until a couple years ago. Also known as the water bear or the moss piglet, tardigrades are microscopic eight-legged animals that make up the phylum Tardigrada, from the latin for "slow walker." There are more than 1,000 species of tardigrades currently known. They are roughly the size of the tip of a pen or pencil, and are commonly found living on lichens or mosses in freshwater habitats.

GIF of footage from Cosmos: A Spacetime Odyssey
Tardigrades have been around a long time, with fossils dating from the Cambrian, a period about 500 million years ago that contained a rapid diversification of lifeforms known as the Cambrian explosion. They have survived every mass extinction event in the history of the Earth.

Image via Wikimedia Commons CC BY-SA 2.5
Image via Wikimedia Commons CC BY 2.5
Tardigrades are extremophiles, meaning they can survive in extreme environments. They have been found living in hot springs and also under layers of polar ice. They can tolerate 1,000 times more radiation than any other animal. They even survived the vacuum of outer space for research performed during space missions in 2007 and 2011.

They are extremely adaptable to these varying environments because of cryptobiosis -- essentially stopping all metabolic processes for a period of time. When conditions stabilize, tardigrades will return to it's normal metabolism.  This makes the water bear a wonderfully unique model organism to study evolutionary biology and the survival of life in extreme situations.




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