What are Tardigrades?

Sept. 13, 2024

Detailed 3D images of the first tardigrade fossils ever discovered help scientists predict when tardigrades evolved their near-indestructibility, which helps them survive in extreme environments.

About Tardigrades:

  • Tardigrades, often called water bears or moss piglets, are microscopic eight-legged animals.
  • They are free-living tiny invertebratesbelonging to the phylum Tardigrada.
  • Around 1,300 species of tardigrades are found worldwide.
  • Habitat:
    • Considered aquatic because they require a thin layer of water around their bodies to prevent dehydration, they’ve also been observed in all kinds of environments, from the deep sea to sand dunes.
    • Freshwater mosses and lichens are their preferred habitat, hence their nickname, moss piglet.
  • They belong to an elite category of animals known as extremophiles, or critters that can survive extreme environments.
    • They can survive punishing heat, freezing cold, ultraviolet radiation and even outer space.
    • Under unfavourable conditions, they go into a state of suspended animation called the “tun” state—in which the body dries out and appears as a lifeless ball (or tun).
    • Tardigrades can survive as tuns for years or even decades.
  • Physical Features:
    • Tardigrades are short, plump, and covered in a tough cuticle (similar to that of grasshoppers and other insects) that they must shed to grow.
    • Tardigrades are mostly about 1 mm (0.04 inch) or less in size. 
    • Their tiny bodies contain no bones and are instead supported by a hydrostatic skeleton – a fluid-filled compartment known as a hemolymph.
    • They have four pairs of legs, with 4-6 claws on each foot.
    • Their specialised mouthpart–called a buccopharyngeal apparatus–allows them to suck the nutrients out of plants and other microorganisms.