"Not far from Clifton is a small hill with an old fishpond at its foot. The slopes are covered with spruce and beech trees, so that the pond is protected on three sides; only a gap remains open to the soft south-westerly winds and the afternoon sun.

A clear spring rises on the hilltop, from which a thin stream of water flows down between the willow bushes into the upper end of the pond. A wide stone wall runs across the valley to dam up the water, and in one corner there is a recess through which the excess water flows in a small cascade into the deeper meadow bottom.

The tranquil mirror of the pond is embroidered with the green leaves of the many aquatic plants and is shaded by three stately beech trees that take root on the banks. But more enchanting than all this to the naturalist's eye is the old stone wall. The ravages of time have eaten away the mortar at water level and created thousands of cracks and tiny cavities. The algae threads grow luxuriantly in them, and they are hiding places for countless living creatures.

If we approach the pond on the gamekeeper's path and step quietly to the corner of the wall, we can survey the pond at a glance without startling the creatures on it. Over on the other bank, a water hen leads the small brood along under the willows; a water rat sits on a tree trunk that has fallen into the water and scratches its right ear, and the clapping of a beechnut just in front of us reveals a squirrel having its meal somewhere in the dense treetop.

But there! The rat has spotted us and dives for its bank cave, and only a slight ripple in the water bears witness to its silent escape. The water hen has taken cover and the squirrel has stopped dropping its shells. It is a truly 'still water', without the slightest sign of life. But if we - while retaining our sight and senses - were to shrink down to a living dwarf and submerge ourselves in the water, what a marvellous world would open up to us! We would see a fairy-tale world of strange creatures, of creatures that swim along with the help of the finest eyelashes, that let ruby-red eyes shine out from deep in their necks, pull telescope-like feet into their bodies and stretch them out again to their full length. There is one of them lying at anchor, held by fine threads that they spin with their toes; and there are others again, flashing in glass-bright carapaces, staring from sharp spines and adorned with humps and flowing curves. There is one attached to a green stalk, drawing a never-ending stream of small victims into its open maw to tear them to pieces with hooked jaws deep down in its body.

Not far away is something that resembles a glassy pansy. A strange mechanism runs around its four outstretched lobes. A chain of tiny living and dead things winds its way to a pit in the neck of the 'flower'. We are no longer able to recognise what is happening to them, because the flower's rotifer is disturbed in its tube of golden-brown spheres. Some strange creature bumps into it and, like lightning, the flower disappears into its tube.

We sink even deeper, and now we see a slowly gliding mass of jelly at the bottom, stretching its shapeless arms out wherever it wants to grab a prey and flow around it to feast on it. It crawls along without feet, grasps without hands, eats without a mouth and digests without a stomach.

I would run out of time and space if I were to recount all the wonders of this underwater world. They would sound like the fantasies of children's fairy tales, and yet they would be literally true. The world of rotifers that I want to describe here is also true ..."

With these words, Hudson and Gosse introduce their great work on rotifers (The Rotifera "Wheel-Anirnalcules"), published in 1886, which described all the rotifers discovered up to that time in great detail and presented them in colourful pictures. We feel that the authors are still living in the world of thought of the great naturalists of the 19th century, their style corresponds to the "sensible observation of nature" that was aspired to at that time. In the meantime, the generation of "naturalists" has given way to the "natural scientist" who dominates today, and "biology" has taken the place of the "description of nature" in order to address deeper questions. But the enthusiasm of the ancients should still be an incentive for us today.

Rotifers are an extremely species-rich and diverse group of aquatic micrometazoa. They live in marine habitats, fresh waters and even in semi-terrestrial habitats such as moist moss cushions and the pore system of the soil. Despite their astonishing diversity of forms and ecological importance, they have been little studied to date due to their size and the associated difficulties in preparation and visualisation. With the development of new microscopic techniques, this situation has changed significantly.