This picture of a Water Bear or Tardigrade (Paramacrobiotus craterlaki) has been floating around Facebook this week. Who knew that an invertebrate could be so cute? I hope the silverfish that I routinely squish in my bathroom don’t look this cute under a microscope. Thanks to the Royal Photographic Society for the photo and the description below.
This fully-grown specimen is about 1mm in length and was found on moss in Crater Lake, Tanzania. Tardigrades, or water bears, are tiny invertebrates that live in aquatic and semi-aquatic habitats such as lichen and damp moss. They require water to obtain oxygen by gas exchange. In dry conditions, they can enter a cryptobiotic state of dessication in which their body water content is just 3 percent. In this state they may survive for decades. P. craterlaki is a carnivorous species that feeds on nematodes and rotifers. Water bears are found throughout the world, including extreme environments such as hot springs and deep underwater. They can also survive the high levels of radiation and vacuum of space.