In a study published in the journal PeerJ, scientists have identified an unexpected factor influencing the spread of invasive flatworms in France. The research was conducted by experts from the Institute of Systematics, Evolution, and Biodiversity at the French National Museum of Natural History, in collaboration with a colleague from James Cook University in Australia. Their findings revealed that domestic animals may play a significant role in transferring this species from one location to another.

How Flatworms Spread

Terrestrial flatworms (Platyhelminthes) are considered invasive organisms that typically expand their range through the movement of plants. This process is closely linked to human activities, particularly gardening and the trade of plants. However, this explanation did not fully answer the question: how do these slow-moving worms end up in neighboring gardens where no new plants have been introduced?

The Role of Domestic Animals

To investigate this, researchers analyzed over twelve years of observations collected through citizen science programs across France. The long-term data allowed them to identify a previously unnoticed pathway of spread: in several cases, flatworms were found on the fur of dogs and cats. This suggests that pets are capable of transporting worms between different areas.

Characteristics of the Species Caenoplana variegata

Among the roughly ten species of flatworms that have invaded France, only one—Caenoplana variegata—was associated with this mode of movement. This species produces especially sticky mucus, which is related to its predatory lifestyle. Additionally, Caenoplana variegata can reproduce without a partner, increasing its chances of establishing new populations after being relocated.

Impact on Global Spread

Since domestic animals travel considerable distances each year, scientists suggest that this method of transfer could significantly contribute to the global spread of certain invasive flatworm species.