Looking at tardigrades (water bears) under the microscope

The humble tardigrade – tiny, strangely adorable, and practically indestructible.

Found almost everywhere on Earth, the microscopic tardigrade, also known as the ‘water bear’ or ' moss piglet', is so unique that all 1300 tardigrade species belong to their own phylum, Tardigrada.

Their widespread habitat and fascinating 8-legged appearance make them a great specimen for any microscope enthusiast.

Meet the tardigrade

Tardigrades are minuscule multicellular animals.Often only 0.5mm long, they have barrel-shaped bodies propelled by 8 stubby legs with long hooked ‘claws’ they use to grip onto mosses and lichen.

Despite their small size, their anatomy is more complex than you might expect. They have organs, muscles, eyes and even a brain.

Instead of bones or an exoskeleton, their body is protected by a strong, flexible covering known as a cuticle.

A natural survivor

However, their most interesting quality is their legendary survivability.When things get tough, a tardigrade can go into a special kind of hibernation called cryptobiosis.

This helps them to survive harsh conditions like extreme heat or cold, lack of water, and even exposure to the radiation-filled vacuum of space.When they are in this state, they shut down their metabolic processes and use a variety of novel defence mechanisms to protect themselves from different kinds of hazardous environments.

In a drought, a tardigrade folds itself into a ball or a barrel shape known as a ‘tun’. This helps to reduce any water loss by minimising its surface area. It also covers itself in wax to further prevent any water from escaping through its skin.

Finally, it protects its internal structure and cell membranes by replacing most of the remaining water in the body with a special protein or sugar mix that hardens into a glass-like state and holds everything in place.Similarly, when a tardigrade is faced with freezing temperatures, it can use another special tardigrade-specific protein to form a glass-like matrix around its cells.

This helps to prevent the freezing water from rupturing their cells and causing damage.Low oxygen, high salt, or harmful toxins? No problem.Tardigrades even have a special protein called ‘Dsup’ (short for ‘damage suppressor’) that helps protect their DNA from radiation damage. It allows them to withstand 1,000 times more radiation than other animals.

These unique adaptations help tardigrades survive almost anywhere, from searing lava fields to freezing wastelands. But despite their hardiness, tardigrades are semi-aquatic and are most at home in moist environments such as ponds, moss, and damp plant matter.If you’d like to see a tardigrade yourself, check out any local ponds or shady parks and forests.

Getting a look at a tardigrade

Although tardigrades can sometimes be hard to find, they’re quite easy to see under a microscope.

You can use either a stereo microscope with a magnification of 40x or biological & brightfield microscope with 40x or 100x magnification.

Optico ASZ-100 Stereo Microscope

Microscopy techniques

You can easily see tardigrades using basic brightfield microscopy. However, they can look even better with more advanced optical techniques.  

Optico N400M-XY Student Microscope

For example, darkfield microscopy will make your tardigrades stand out against a dark background. DIC and phase contrast will give you a clearer view of their features and structure.

And because their muscles, organelles, and mouth have a special quality called birefringence, polarized light microscopy will make your tardigrades look like a colorful night sky.