Writer: Lava Naz Bagdu
While most living creatures biologically can’t survive in space without special equipment due to harsh conditions such as extreme heat, pressure, and lack of oxygen, there is an extraordinary exception for that: tardigrades. In this article, we will talk about tardigrades, their general features, and how they can survive under such extreme circumstances.
What Are Tardigrades?
Tardigrades, also known as water bears or moss piglets, are near-microscopic, eight-legged invertebrates belonging to the phylum Tardigrada. They share a distant evolutionary relationship with arthropods (eg. insects, arachnids). Tardigrades typically measure about 1 mm (0.04 inch) or less in size and their eight legs are paired and located in four segments. They live in various habitats such as damp moss, flowering plants, and freshwater. There are approximately 1,300 tardigrade species found worldwide, and they are considered aquatic (“living in, happening in, or connected with water”) because they require a thin layer of water around their bodies to prevent dehydration. According to the University of Michigan’s Animal Diversity Web (ADW), Tardigrades can survive in a wide variety of environments, from elevations above 6,000 meters (19,600 feet) in the Himalayan mountain range to ocean depths 4,700 meters (15,000 feet) below the surface (Bradford, A., 2022; Wright, J., n.d.; National Geographic, n.d.; Britannica, 2023; Cambridge Dictionary, 2024).
A tardigrade (Paramacrobiotus craterlaki) in moss. (sciencephoto.com)
How Can They Survive in Hard Conditions?
A tardigrade’s survival talents include a process called cryptobiosis. In this state, the organism enters a state of suspended animation or extreme dehydration, allowing it to withstand harsh environmental conditions that would normally be lethal. During this process, the organism can live for a longer period because metabolic activities are drastically reduced or almost entirely halted, preserving the organism in a dormant state until the conditions are favorable again. Tardigrades can survive the lack of water, high levels of radiation, and even a vacuum of space utilizing cryptobiosis (Byjus, 2024).
An Example For Radiation Resistance
According to a study titled “Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein” published in September 2016, tardigrades are also adept at reducing the effects of radiation. They can withstand hundreds of times the amount of radiation that would kill a human. Employing a protective protein called Dsup (short for “damage suppressor”) coating their DNA, they become resilient to radiation. Hashimoto and his colleagues also found that transferring some of the Dsup to human cells helped them lessen x-ray-induced damage up to 40 percent, a skill that one day might translate into helping humans better withstand radiation therapy treatments or equip us for life on Mars. (Pfizer, n.d.; Hashimoto et al., 2016)
However, tardigrades do have a fatal weakness: exposure to hot water. A 2020 research shows that tardigrades can be killed by exposure to hot water for an extended period. One study showed that one hour of exposure to water at 82.7 degrees Celcius (180.9 degrees Fahrenheit) can kill a tardigrade in its “tun” state, where it goes into suspended animation and becomes hard to destroy. (Britannica, 2023; Weisberger, et al., 2022)
As a result, tardigrades' resilience and extraordinary survival mechanisms make them the real, resilient marvels of the natural world. Tardigrades not only contribute to our understanding of biological adaptations but also have potential applications in many fields, from medicine to technology. Their ecological significance and the ongoing discoveries surrounding them highlight the importance of these tardigrades in the complex web of life.
Moreover, with their incredible resistance to radiation and unique genetic structure, tardigrades provide valuable information for future space exploration and searches for extraterrestrial life. Their ability to survive in the harshest environments on Earth prompts us to consider broader implications for astrobiology and the potential habitability of distant planets.
References
Bradford, A., (2022), What are tardigrades and why are they nearly indestructible?, Live Science, https://www.livescience.com/57985-tardigrade-facts.html
Tardigrade, National Geographic, (2024.01.14) https://www.nationalgeographic.com/animals/invertebrates/facts/tardigrades-water-bears
Tardigrade | Facts & Lifespan, (2023), Britannica, https://www.britannica.com/animal/tardigrade
The Tiny Creature That May Teach Us How to Survive Radiation, Pfizer, (2024.01.15), https://www.pfizer.com/news/articles/tiny-creature-may-teach-us-how-survive-radiation
What Is Cryptobiosis? - Types & Examples Of Cryptobiosis, BYJU'S, (2024.01.14), https://byjus.com/biology/cryptobiosis/
Wright, J., ADW: Tardigrada: INFORMATION, Animal Diversity Web, (2024.01.14), https://animaldiversity.org/accounts/Tardigrada/
Hashimoto, T., Horikawa, D. D., Saito, Y., Kuwahara, H., Kozuka-Hata, H., Shin-I, T., Minakuchi, Y., Ohishi, K., Motoyama, A., Aizu, T., Enomoto, A., Kondo, K., Tanaka, S., Hara, Y., Koshikawa, S., Sagara, H., Miura, T., Yokobori, S., Miyagawa, K., Suzuki, Y., Kubo, T., Oyama, M., Kohara, Y., Fujiyama, A., Arakawa, K., Katayama, T., Toyoda, A. & Kunieda, T., (2016), Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein, Nature Communications,
Aquatic, Cambridge Dictionary, (2024.01.15),