Tardigrades, often called “water bears” or “moss piglets,” are fascinating microscopic animals. They have earned a reputation for their extraordinary resilience, capable of surviving conditions that would be lethal to most other forms of life. Their unique biological adaptations allow them to persist in some of Earth’s harshest environments.
Do Tardigrades Live on Human Eyelashes?
Tardigrades do not reside on human eyelashes. These microscopic animals are aquatic, requiring a consistent film of water to remain active. Human eyelashes and the surrounding skin do not provide the stable, moist environment necessary for a tardigrade to live an active life. While tardigrades can enter a state of suspended animation to endure dry periods, they cannot thrive in such an arid habitat.
The Real Habitats of Tardigrades
Tardigrades are found across the globe, inhabiting a wide array of environments from mountaintops to the deep sea, and from tropical rainforests to the Antarctic. Their most common habitats include damp mosses, lichens, and leaf litter, where they live within thin water films. They also thrive in freshwater sediments, marine environments, and hot springs. These locations highlight their adaptability.
A key to their survival in fluctuating environments is their ability to enter cryptobiosis, a reversible state of suspended animation. During cryptobiosis, tardigrades can withstand extreme desiccation, freezing temperatures as low as -272 °C, and high temperatures up to 149 °C. They can also survive intense radiation, the vacuum of space, and immense pressures. In this state, their metabolism can slow to less than 0.01% of normal, and their body water content can drop to about 1%, allowing them to persist for years or even decades until favorable conditions return.
Other Microscopic Residents of Human Skin
While tardigrades do not colonize human eyelashes, other microscopic organisms commonly inhabit human skin, including the area around the eyes. Demodex mites are frequent residents of hair follicles and sebaceous (oil) glands on the face and eyelashes. These arachnids feed on dead skin cells and the oils produced by glands.
Demodex mites are a normal part of the human skin microbiome, and most adults host them without issues. However, if their populations grow excessively, they can lead to conditions like blepharitis, causing symptoms such as itching, redness, and inflammation of the eyelids. Beyond mites, the skin also supports a diverse community of bacteria, which contribute to the skin’s natural balance and health.