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Tardigrades

Crash Course 2026!

Starts 16^th

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.

Marine tardigrades account for 17% of all known tardigrade species and are found in all the oceans.

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.

Cryptobiosis is a state of extreme inactivity in response to adverse environmental conditions. In the cryptobiotic state, all metabolic procedures stop, preventing reproduction, development, and repair. For example, they turn the cytoplasmic fluid of cells into a glass-like structure to survive dehydration.

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.
- 1^st animal to survive direct exposure to space during the European Space Agency’s Foton-M3 mission (2007).

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