flatworm

Imagine a worm, but pressed flat like a ribbon. That is what this creature is like. It has a soft, simple body and lives in wet places, from ponds and oceans to the bodies of other animals. Some kinds live freely and eat tiny living things. Others are parasites, which means they live on or inside another animal and take food from it. A tapeworm is one well-known example. Some kinds are also known for their strong ability to regrow lost body parts.

Flatworms are soft-bodied animals in the phylum Platyhelminthes. Their name comes from their flat shape. Unlike roundworms, they do not have a true body cavity, and their bodies are built in a simple way. Some are tiny enough to be hard to see, while others can grow quite long, though most are small.

You can find them in freshwater, in the sea, and inside other animals. Some kinds live freely, but many are parasites, including flukes and tapeworms. Flatworms do not have a special blood system or breathing system. Instead, oxygen and nutrients move through their bodies in simple ways. They can reproduce sexually or asexually, and some species can regrow missing parts, which has made them especially interesting to scientists. While many cause no harm to people, parasitic kinds can lead to disease in humans and other animals. Because of this, they matter both in nature and in medicine. When you hear the word, think of a simple, flat-bodied animal that may live on its own or inside a host.