Tardigrades, also known as water bears or moss piglets, are microscopic animals renowned for their remarkable resilience. These tiny creatures, typically around 0.5 millimeters long, are found globally in diverse environments, from mountaintops to deep-sea trenches. Their ability to survive extreme conditions, including intense temperatures, radiation, and even the vacuum of space, makes them some of Earth’s hardiest organisms. Observing these fascinating invertebrates under a microscope offers a unique glimpse into a hidden world.
Essential Equipment for Observation
Gathering the appropriate tools is the first step for observing tardigrades. A compound microscope is recommended, with a magnification range of 100x to 400x suitable for detailed viewing. While a stereo microscope can be used for initial scanning (e.g., 20x-50x), a compound microscope allows for closer inspection of tardigrade features.
Other essential items include:
Microscope slides and coverslips to prepare samples.
Pipettes or droppers for transferring water and specimens gently.
Small collection containers, such as petri dishes or shallow jars, for holding samples.
A light source, if not built into your microscope, to illuminate subjects.
Where to Find Tardigrades
Tardigrades are surprisingly widespread and can be found in many common, accessible habitats. Mosses and lichens are among the most productive sources for locating these micro-animals. Look for these plant types growing on tree barks, rocks, roofs, pavements, or even old gravestones.
These tiny creatures thrive in moist environments, relying on a thin film of water for their movements and survival. Damp, undisturbed areas are often the best places to search. Leaf litter and sediment from freshwater sources, such as ponds or puddles, can also harbor tardigrades. Collecting samples a day or two after a rain shower can increase your chances of finding active specimens, as the moisture encourages them to emerge from dormant states.
Collecting and Preparing Samples
Collecting samples for tardigrade observation requires gentle handling to avoid harming the delicate organisms. When gathering moss or lichen, carefully scrape or collect small clumps, ensuring not to damage the underlying growth. Place these samples in separate containers, like paper bags or small plastic containers, labeling each with the collection date and location.
Once collected, dry samples need rehydration. Submerge the moss or lichen in water, preferably spring water or dechlorinated tap water. Allow samples to soak for 3 to 24 hours; this revives tardigrades from their cryptobiotic “tun” state, encouraging activity.
After rehydration, gently squeeze water from the moss or lichen into a clean, transparent dish. Using a pipette or dropper, transfer a few drops of this water, particularly from the bottom where debris and tardigrades tend to settle, onto a clean microscope slide. Carefully lower a coverslip over the water droplet, ensuring no air bubbles are trapped, and gently press to remove any excess water.
Observing Tardigrades Under the Microscope
With your prepared slide, place it onto the microscope stage and begin observation at a lower magnification, such as 40x or 100x. This wider field of view allows you to scan the sample efficiently and locate potential tardigrades, which typically measure between 0.1 and 1.5 millimeters. Once a promising specimen is found, gradually increase the magnification to 200x or 400x for a more detailed view.
Tardigrades are recognizable by their distinctive barrel-shaped bodies and eight stubby legs, each ending in claws or suction cups. They often exhibit a slow, lumbering walk. Their bodies can be translucent, allowing glimpses of their internal structures. Adjusting the microscope’s focus and the light source will enhance visibility, revealing the fine details and movements of these micro-animals.