Flatworms are a topic often discussed within the world of worms; there are 25,000-odd species of them and they come in all sorts of colors and are extraordinary creatures. Unfortunately, their odd, flat shape alone has given them a bad reputation and has spawned a lot of awful, and a lot of times false, rumors about them.
Flatworms all belong to the phylum Platyhelminthes, who are all invertebrates characterized by their soft, flat bodies. According to The Encyclopedia Britannica, 80% of flatworms are parasitic, meaning they feed on and grow inside other organisms. However, the other 20% are free-living, meaning they inhabit terrestrial or aquatic habitats. Their bodies are devoid of circulatory, respiratory and skeletal systems, and they are bilaterally symmetrical, meaning if you cut them down the middle, both sides would be exactly identical. As well as being hermaphroditic, thus possessing both male and female reproductive systems, some species of flatworms even have the power of cell regeneration, such as planarian flatworms, meaning they can grow back body parts if cut off. Technically, their entire body is one body part, but if, for example, a head was cut off, it would grow back.
Now, when it comes to the misconceptions regarding flatworms, one is that flatworms are universally dangerous. Whilst 80% of flatworms are parasitic, most of them are not parasitic to humans. Of course, there are certain species that are parasitic to mammals, such as the Multiceps multiceps, which takes sheep as their hosts, so these species could be a concern for pet/farm owners. In fact, the only species of flatworms that pose a threat toward humans are flukes and tapeworms. Out of all species of flukes, only thirty-six have been known to infest humans. Similarly, although most sources disagree on the number of species of tapeworm that exist, whether there are over 1000 species, or 5000, the number of species of flukes and tapeworms that are dangerous to humans combined would not add up to 1/5 of the total amount of species of flatworms.
Furthermore, another common misconception that pertains to flatworms is specific to the New Guinea flatworm. Upon their discovery in the United States as an invasive species, article after article demonizing these flatworms was written. Although articles claiming the flatworms posed a negative environmental impact were fair and well-reasoned, other articles simply made them out to be monsters based on the fact that they were an invasive species. One concern that led to a minor case of hysteria in Florida was the fact that the New Guinea flatworm could supposedly carry a parasite called the ‘rat lungworm’. In a human, this parasite could cause meningitis and thus Florida residents were told to ‘beware’ this worm. However, the rat lungworm parasite can only be contracted if one ingests the previous host, meaning that one would have to eat a New Guinea flatworm to become infected with the rat lungworm parasite. Hence, the chances of becoming infected by this parasite from the New Guinea flatworm are slim to none. Yet, people were so sure of their potential threat, that Florida residents began to call the police upon the discovery of a New Guinea flatworm, and began labeling the situation as one that constituted taking such action. On that note, another source stated that the New Guinea flatworm is itself parasitic to animals, but no other sources indicate this, so the validity of this statement is questionable. These misconceptions are placed on multiple species of flatworms which are, in actual fact, mostly harmless.
To conclude, this has been a brief overview of a couple of common misconceptions about flatworms. No, they are not all dangerous, and no, their presence does not validate bothering the police. That is not to say that one should not be wary when they encounter an unfamiliar creature, but to panic and cause mass hysteria is also not the way to go about it, as it helps absolutely no one. We hope that this article proved to be helpful and interesting to our readers, and that they have learnt something new about flatworms today!