simple animals

3. The immature, free-swimming form of many familiar animals.
4. The simplest type of sponge body plan.
8. The central cavity of a sponge.
9. pores in a sponge through which water enters.
10. An organism that lives at the bottom of a body of water.
13. Microscopic organisms drifting in the sea or freshwater, or the young form of aquatic animals.
15. Organisms that are fixed in one place and cannot move.
16. Having male and female reproductive organs in separate sexes.
17. An organism that possesses both male and female reproductive organs.
20. A fibrous protein that forms the flexible skeleton of some sponges.
21. A small, pointed structure found in sponges.

1. Whip-like appendages that enable many bacteria and sperm cells to swim.
2. A form of cnidarian, typically having a tubular body attached to a surface at one end and a mouth surrounded by tentacles at the other.
5. Having both male and female reproductive organs in the same individual.
6. A type of vacuole that expels excess water from a cell.
7. The most complex type of sponge body plan with extensively branched canals.
8. A type of sponge body plan characterized by folded walls.
11. The free-swimming, ciliated larva of a cnidarian.
12. A form of asexual reproduction in which a new organism develops from an outgrowth or bud.
14. Feeder: An animal that feeds by straining suspended food matter from water.
18. A free-swimming sexual form of a Cnidarian, typically jellyfish-like in form.
19. A large opening in a sponge that expels water.