1. Compare size, structure, habitats, and relative complexity of the different invertebrates.
2. Discuss possible reasons why there was a sudden explosion of development of animal phyla during the early Cambrian period.
3. Compare the inverted structures of the medusa and polyp forms of cnidaria, and examine how the body structure is different from that of a sponge.
4. Compare the body structure of the flatworm and
the roundworm, with emphasis on body layers, digestive tract,
and reproduction.