CK12 Life Science

and intestines. The circulatory system consists of paired hearts and blood vessels, while the
nervous system consists of the brain and a ventral nerve cord.

Table 11.2:

Type of Worm Body Cavity Segmented Digestive Sys-

tem

Example

Flatworm No No Incomplete Tapeworm

Roundworm Yes No Complete Heartworm

Segmented Yes Yes Complete Earthworm

(Source:Jessica Harwood,License:CC-BY-SA)

Lesson Summary

• The flatworms have no true body cavity and include free-livingDugesiaand parasitic
  tapeworms.


• The roundworms, which can also be parasitic or free-living, are non-segmented worms
  with a complete digestive tract and a primitive brain.


• The segmented worms include the common earthworm and leeches.

Review Questions

1. Are all worms classified into a single phylum?


2. Describe the respiratory system of the flatworms.


3. What is cephalization?


4. Name a parasitic flatworm.


5. How does the body plan of the roundworms differ from that of the flatworms?


6. Describe the digestive system of roundworms.


7. What features distinguish Phylum Annelida from the other worms?


8. Describe the skeletal system of a segmented worm.


9. Name a parasitic segmented worm.


10. Earthworms are in what phylum?

Further Reading / Supplemental Links

• http://animaldiversity.ummz.umich.edu/site/accounts/information/Annelida.
  html


• http://animaldiversity.ummz.umich.edu/site/accounts/information/Nematoda.
  html