TV wildlife documentaries tend to focus on large animals with fur or feathers, but most of the animal world is tiny and many of the microscopic life forms that live in the water or in soil, that play a vital role in the functioning of ecosystems, are poorly understood. This animal is a gastrotrich – a name that literally means ‘hairy stomach’, on account of the tiny beating hairs on its underside that propel it through the water. These restless little animals, none longer than half a millimetre, are in every pond and also occur in marine environments, but compared with larger life forms we know very little about the lives of the 400 or so species that have been discovered so far. If you have a garden pond, or any water in the garden that contains decaying vegetation, there’ll be gastrotrichs in it, along with the heliozoans and rotifers that I mentioned in earlier postings. Gastrotrichs are fast moving, endlessly exploring detritus in the water in search of a meal, and defend themselves with tiny spines on the body surface. I used DIC optics again for these pictures, to highlight the animal’s spiny covering.