How long can a human survive without drinking water? – around 100 hours. Yet, there exists a creature that can survive decades without water. Not just that, this creature can adapt and live for years in any harsh environment, unaffected by extreme radiation or severe cold. Its name is Tardigrade.
Tardigrades are not imposing in appearance. They are about a millimeter long, with eight legs, each equipped with clawed feet. Under a microscope, they resemble a microscopic version of a chubby bear. German scientist Johann August Ephraim Goeze first observed them in 1773. Due to their slow movement, they were named Tardigrada (meaning “slow stepper” in German) by Lazzaro Spallanzani, an Italian biologist who hinted at their extraordinary abilities.
Before delving into the Tardigrade’s ability to survive without water, let’s understand why water is essential for life. Water is crucial for various biochemical processes within cells. Tardigrades utilize a process called anhydrobiosis to practically halt their metabolic activities when dehydrated. In the absence of water, they curl into a ball, entering a state known as “Tun”. Scientists believe a specific molecule within Tardigrades forms a sticky matrix that substitutes for water within cells, protecting them from damage. Remarkably, this matrix shields vital components like DNA and proteins from degradation. When rehydrated, Tardigrades resume their active state.
Tardigrades’ habitats are ubiquitous. Since they thrive in adversity, they are found everywhere from mountains and fields to oceans and even outer space. Their unique ability to withstand radiation led to their being sent into space. In 2007, several species were sent into low Earth orbit in a dehydrated state on NASA’s FOTON-M3 mission. Upon rehydration on Earth, they revived after 30 days. In 2011, they survived another space mission, STS-134. This extraordinary resilience has piqued scientific interest. By leveraging this trait, scientists hope to revolutionize our understanding of surviving radiation.
Researchers have observed success in studying Tardigrades. They’ve noted that genes coding for Intrinsically Disordered Proteins (IDPs) play a crucial role in Tardigrades’ anhydrobiosis. Unlike most proteins, IDPs lack a fixed structure, making them adaptable. Incorporating IDP genes into bacteria showed that these proteins help bacteria survive desiccation. There’s speculation that Tardigrades might be extraterrestrial due to their ability to survive without oxygen in space, but like any other creature, Tardigrades have evolved on Earth. Their genome analysis reveals a mix of genes from various species, including plants, fungi, bacteria, and viruses, which contribute to their survival in harsh conditions. The presence of a Damage Suppressor Protein (Dsup) protects their DNA from radiation. Introducing Dsup into human cells could potentially increase our resistance to radiation by 40%. Tardigrades, having survived evolutionary challenges, hold a significant place in the animal kingdom and could provide vital insights for human survival strategies in future, more hostile environments.
