- Animals can be classified by both molecular data and physical characteristics such as
symmetry. - Invertebrates are animals without a backbone.
Review Questions
- What are some key features that define the animal kingdom?
- What does heterotrophic mean?
- What defines the invertebrates?
- What are some examples of invertebrates?
- What is the difference between radially and bilaterally symmetrical animals?
- What’s an example of a bilaterally symmetrical animal?
- What are some examples of a radially symmetrical animal?
- What is a body cavity?
- What is the difference between an incomplete and complete digestive system?
- What is segmentation?
Further Reading
- http://animaldiversity.ummz.umich.edu/site/index.html
- http://doe.sd.gov/octa/ddn4learning/themeunits/animals
- http://animals.nationalgeographic.com/animals/invertebrates.html
- http://en.wikipedia.com
Vocabulary
bilaterally symmetrical Body plan in which the left and right side are mirror images.
complete digestive tract A digestive tract that has two openings, the mouth and the
anus.
heterotroph Organism that cannot make its own food, so it must ingest some type of
organic matter.
invertebrates Animals without a backbone.
incomplete digestive tract A digestive tract that has only one opening.
radially symmetrical A body plan in which any cut through the center results in two
identical halves.
segmentation Repetition of body parts or segments.