Flat, slimy, and often sporting warning colours like bright orange or yellow stripes, this creature looks less like a worm and more like a piece of living ribbon that forgot how to tie itself. It moves with an eerie, gliding motion, propelled by microscopic hairs and a layer of mucus that would make a snail jealous. Do not be fooled by its gentle appearance. This is a ruthless predator. Flatworms hunt earthworms, snails, and slugs. They wrap themselves around their prey, smothering it in slime and digestive enzymes before literally sucking the softened tissues out. It is a gruesome, efficient method of dining that has made some introduced species a serious threat to New Zealand's native earthworm populations. They are the wolves in sheep's clothing of the invertebrate world, looking fragile but acting like apex predators in the micro-ecosystem. They are hermaphrodites and can reproduce sexually or by simply tearing themselves in half, with each half growing into a new worm. That party trick makes them notoriously difficult to eradicate. If you find one in your garden, picking it up with bare hands is ill-advised. Their slime can be irritating, and they are surprisingly sticky. They are a fascinating but somewhat unsettling reminder that even the softest creatures can be deadly. What makes these animals particularly successful is their complete lack of a respiratory or circulatory system. They absorb oxygen directly through their moist skin, which is why they must stay in damp environments. Their flattened body shape maximises surface area for gas exchange while keeping them low enough to slip under rocks and logs. Some native species have evolved striking camouflage patterns that mimic the veining of leaves, allowing them to disappear on the forest floor. The introduced Australian flatworms, by contrast, often sport bright warning colours that advertise their toxicity to predators. Birds and lizards learn quickly to avoid the orange-striped invaders, giving them an edge over the more subtly coloured native species. This chemical defence, combined with their aggressive hunting behaviour and asexual reproduction, explains why the interlopers have spread so rapidly across the New Zealand landscape.