For the first edition of Science Sundays on this blog, I'm going to talk about my favorite microscopic animal of all time. These cute little guys are called water bears (due to their bear-like gait), or tardigrades. They're arthropods from the phylum Tardigrada, and oh yeah, they're nearly indestructible.
Water bears are small; they range from 0.3-0.5mm, and have four pairs of legs. These little guys have been found almost everywhere--including in sheets of ice and at the top of the Himalayas. Most of them live in moist places though, preferring patches of moss and the like. Something peculiar about them is that they're eutelic, which means that every single member of a species have the same amount of cells in their body. I think that's kinda neat. But even neater than that is the ridiculous amount of things that they can survive.
Water bears can survive:
- Temperature extremes– They can survive temperatures from 151 °C to -200 °C. They can even survive for a few minutes at temperatures near absolute zero.
- High Pressures- They can withstand the pressure of 6,000 atmospheres, which is almost six times the pressure of the very bottom of the ocean.
- Dehydration- Some species have been known to survive up to 10 years in a type of stasis known as cryptobiosis.
- Radiation– They can survive doses of 5,000 grays of radiation--5 or 10 are enough to kill a human.
- The Vacuum of Space – They have been known to survive for 10 days in space when protected from radiation, and sometimes even if they aren't protected from cosmic rays.