Tardigrades

Topic: Biodiversity

Why in the news?

• Detailed 3D images of the first tardigrade fossils ever discovered help scientists predict when tardigrades evolved their near-indestructibility, a trait that might have helped them survive multiple mass extinctions.

Source: Down To Earth

About Tardigrades:

• These are often called water bears or moss piglets.
• These are microscopic eight-legged animals.
• They are free-living tiny invertebrates belonging 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 specialized mouthpart–called a bucco pharyngeal apparatus–allows them to suck the nutrients out of plants and other microorganisms.