Tardigrades
- Context (IE): Indian astronaut Shubhanshu Shukla is leading the Voyager Tardigrades Experiment on the International Space Station to study their DNA repair and survival in space.
- Tardigrades, also known as “water bears” (not related to actual bears) or “moss piglets,” are multicellular aquatic micro-animals with a history that predates the dinosaurs by around 400 million years.
- Emerged approx. 600 million years ago and have survived all five of Earth’s mass extinction events.
- Distribution: Found globally — from high mountains and polar ice to ocean depths and tropical forests.
- Most commonly found in moist environments like mosses, lichens, leaf litter, and soil.
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- Habitat: Aquatic microhabitats requiring thin water films on terrestrial surfaces.
- Survive extreme environments—hot springs, deep sea, deserts, & even outer space (in dormant state).
- Physical Features: Microscopic, eight-legged invertebrates with clawed feet. | Size: ~0.3 to 0.5 mm | No circulatory or respiratory system.
- Behaviour & Survival Mechanism: Among the toughest known organisms on Earth. Can survive temperatures from −272°C to 150°C, high radiation, the vacuum of space, and oceanic pressures.
- Enters cryptobiosis and anhydrobiosis (extreme dehydration and drastically slows its metabolism), forming a “tun” state to survive stress.
- Produces Cytoplasmic Abundant Heat Soluble Proteins (CAHS) proteins, which are gel-like cell protectants, Tardigrade Radiation Immunity Determinant 1 (TRID1) Protein, and high antioxidants for rapid DNA repair after radiation exposure.
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- Lifespan: Can survive for decades in a dormant state; a few months to a couple of years when active.
- Diet: Feeds on plant cells, algae, and tiny invertebrates by sucking cellular fluids.
- Conservation Status: Not evaluated by IUCN.
- Significance: Key to space biology and biotechnology, with applications in astronaut health, radiation shielding, and cryopreservation.
