1What is an invertebrate?
2Why is invertebrate an odd way to name such a large group of animals?
3What single question puts all five groups into order? Explain what it shows.
4Why can a protozoan never grow large?
5What is unusual about a sponge's body, and how does that explain regeneration?
6What is the practical problem with having only one opening for food and waste?
7Why is a flatworm flat?
8What does having two openings allow a roundworm to do that a hydra cannot?
9What does hermaphrodite mean, and which group in this topic is usually hermaphrodite?
10How do Ascaris and hookworm get into people, and what can be done about it?