'However, some have been here for over 100 years, so they are well established. are not native,' says Matt Bertone, an entomologist at NC State University. 'The majority of land flatworms in the U.S. Over the course of the past couple of hundred years, global commerce has helped the hammerhead worm wriggle its way into most suitable habitats in the world - and there are a lot of suitable habitats out there, although you're unlikely to find them in a desert or at the top of a mountain. These predatory planarians are native to tropical and subtropical regions of the globe, so they love wet, warm spots. Some land species move using body contractions in a similar way to earthworms.But hammerhead worms, all members of the genus Bipalium, aren't something to get too fussed about as they're not a new thing in the U.S., or in most places in the world - they've been common residents of American gardens since the early 1900s. Thousands of tiny hair-like structures on the side of planaria may beat in motion along secreted mucus for movement in water. As a form of asexual reproduction, planaria have a fascinating ability to regenerate into two separate individuals after damage, or can attach themselves to substrate, pulling their body to cleave themselves into two parts which then regenerate.

Sexual planaria are hermaphrodites, possessing both male and female organs and able to lay eggs. Some larger terrestrial species eat earthworms by wrapping around them, secreting mucus to dissolve their prey. Planaria are carnivores, feeding on a variety of smaller invertebrates such as shrimp and water fleas in aquatic habitats, or other small worms.

It is unknown how many species of planaria exist globally, although there are thought to be 12 species in the UK, alongside invasive non-native species introduced from other parts of the world. Historically, planaria were classified by their ‘ecotype’, or where they occurred, as there are species that live on land in terrestrial ecosystems, freshwater ecosystems, or in marine ecosystems. AboutPlanaria, or planarian flatworms, are thought to be very primitive creatures as they only possess a ladder-like nervous system.

Worms with flat heads