Tardigrades, often called water bears or moss piglets, are microscopic invertebrates that captivate scientists and enthusiasts. These eight-legged creatures, measuring around 0.5 millimeters, are renowned for their remarkable resilience. Their extraordinary ability to withstand extreme conditions makes them popular subjects for amateur microscopy. Uncovering these fascinating organisms provides a unique window into the hidden world of microscopic life.
Where Water Bears Live
Water bears inhabit diverse environments across the globe, from mountaintops to the deep sea. Despite their wide distribution, they are most readily found in specific microhabitats that retain moisture. Mosses and lichens are prime locations, especially on rocks, trees, and roofs, as they provide a sponge-like environment with small water pockets.
Leaf litter on the forest floor also offers a suitable dwelling for tardigrades, as it often remains damp and provides shelter. Additionally, the sediment found at the bottom of freshwater ponds, lakes, or even puddles can harbor these tiny animals. While less common, garden soil can sometimes yield tardigrades, particularly in areas that stay consistently moist.
Collecting Samples
Gathering samples to find water bears requires only a few simple tools. A small trowel or tweezers can be useful for carefully collecting moss, lichen, or leaf litter without causing significant disturbance to the environment. Plastic bags or small containers are ideal for transporting samples, ensuring they remain contained.
For dry moss or lichen, rehydration is necessary to revive any dormant tardigrades. Place the dry sample in a shallow dish, such as a Petri dish, and add distilled water or rainwater, avoiding tap water due to chlorine content. Allow the sample to soak for 3-24 hours; overnight soaking is often recommended for best results. After rehydration, gently squeeze the water from the moss or lichen into a separate dish, which will concentrate any active tardigrades.
Observing Your Discoveries
Once samples are collected and rehydrated, a microscope is necessary to observe water bears, as they are too small for the naked eye. A compound microscope with 40x to 400x magnification is suitable for beginners. You will also need microscope slides and coverslips to prepare your samples for viewing.
To prepare a wet mount, place a small amount of the rehydrated moss or sediment onto the center of a clean microscope slide. Add a drop or two of distilled water to the sample, ensuring it is sufficiently moist. Carefully lower a coverslip over the sample, avoiding air bubbles. Begin scanning the slide under the lowest magnification (typically 40x) to locate tardigrades, then increase magnification for a detailed view. Tardigrades may move slowly at first if emerging from their dormant state.
Caring for Your Water Bears
After locating water bears, you can keep them for continued observation with minimal care. The primary requirement is to keep their samples consistently moist using distilled water or rainwater. Storing the samples in a cool, dark place, such as a Petri dish or small jar, helps maintain their environment.
Tardigrades possess an extraordinary ability called cryptobiosis, allowing them to enter a suspended animation-like state when conditions become unfavorable, such as desiccation. In this “tun” state, they can survive for extended periods, even decades, with their metabolism slowing to less than 0.01% of normal levels.
They can revive within minutes to hours when rehydrated. While fascinating, these organisms are not pets and should ideally be returned to their natural habitat after observation to ensure their well-being.