Flatworms

Definition

Flatworms are a group of invertebrates characterized by their flattened, bilaterally symmetrical bodies. They belong to the phylum Platyhelminthes and include many parasitic species.

5 Must Know Facts For Your Next Test

1. Flatworms lack specialized respiratory and circulatory systems, relying on diffusion for gas exchange.
2. They have a simple digestive system with only one opening that serves as both mouth and anus.
3. Many flatworm species are parasitic, including tapeworms and flukes which infect various hosts.
4. Flatworms exhibit a form of regeneration, allowing them to regrow lost or damaged parts.
5. Their nervous system is relatively simple but more advanced than that of cnidarians, featuring a pair of nerve cords.

Review Questions

Related terms

Tapeworms:

Parasitic flatworms that live in the digestive tract of vertebrates.

Flukes: A type of parasitic flatworm found in various organs of host animals.

Platyhelminthes:

The phylum to which flatworms belong, encompassing both free-living and parasitic species.