The creature you’ve discovered is likely the New Zealand flatworm, a species known scientifically as Arthurdendyus triangulatus. Originally from New Zealand, this flatworm has made its way to gardens across various parts of the world, particularly in the UK and parts of Europe. It is an invasive species that thrives in cool, damp conditions, making gardens an ideal habitat.
New Zealand flatworms are predators that primarily feed on earthworms, which can have devastating effects on soil health and garden ecosystems. Their flat, ribbon-like bodies are uniquely adapted to slip through the soil, and their dark purple coloration helps them blend into the shadows beneath pots and stones, where they often hide during the day.
3. How To Positively Identify A New Zealand Flatworm
Identifying a New Zealand flatworm can be done by noting several distinctive characteristics. First, look at its color: a dark purple or brown body with a pale border is a clear indicator. The flatworm’s body is flat and elongated, measuring between 5 to 15 centimeters in length, although larger specimens have been reported.
These flatworms are smooth to the touch and lack any visible segmentation, unlike earthworms. When disturbed, they may curl up or attempt to escape by gliding along the ground. Observing these behaviors, along with their physical traits, can help confirm their identity.
4. Why This Flat, Purple ‘Liver Blob’ Loves Hiding Under Pots
New Zealand flatworms prefer environments that are cool, dark, and moist, conditions which are often found beneath garden pots, stones, and logs. The underside of a pot provides a perfect microhabitat, offering protection from predators and harsh weather, while maintaining the humidity and temperature levels they need to survive.
