It’s not very often that I come across these very cool creatures, but I did recently while flipping rocks along a creek. Land Planarians are a type of flatworm that have about 1,000 different species living worldwide. The Wandering Broadhead Planarians are identified as flat, yellow and with a dark stripe down the middle of their backs. They are quite slimy, like a slug. Apparently the slime helps them move as well as maintain internal moisture levels.
Wandering Broadhead Planarians are nocturnal predators that feed on slugs, snails, pillbugs, millipedes, spiders and earthworms. They use chemical signals that are produced in folds of their skin to detect prey. When a land planarian feeds, it slimes over top of potential prey, attaches its mouth opening and vomits digestive juices, liquifying its food. Then it sucks up the soupy nutrients.
Like many other flatworms, they are able to reproduce either sexually or asexually. Sexual reproduction culminates in eggs being placed in cocoons that hatch in three weeks. A single planarian will, every couple of weeks or so, attach its tail to a rock or some other immoveable object and slime away, tearing its tail from its torso. A new tail grows from the wound, as we might expect of a flatworm. The tail segment left behind, however, grows a new torso and head within 10 days.
I often think of these strange creatures as being in the tropics and although I found these on a chilly Ohio day, they are indigenous to Southeast Asia. In the United States, they were first encountered in 1943 in Westchester County, New York. Since that time, and despite the disparity in climate between the USA and Southeast Asia, they have spread practically from coast to coast.