1. Ch 33 – Sponges, Cnidarians, and Ctenophores
Vocabulary Review
Ch 33 – Sponges, Cnidarians, and Ctenophores

2. An aquatic invertebrate of the phylum Porifera that attaches to stones or plants and that has a porous structure and a tough, elastic skeleton
Sponge

3. Describes an organism that remains attached to a surface for its entire life and does not move
Sessile

4. Any of the flagellate cells that line the cavities of a sponge
Choanocyte

5. One of the small openings in a sponge’s body through which water enters
Ostium

6. An opening in a sponge’s body through which water exits
Osculum

7. A fibrous protein that contains sulfur and composes the fibers of the skeleton of some sponges
Spongin

8. A needle of silica or calcium carbonate in the skeleton of some sponges
Spicule

9. In an aquatic animal, a method of feeding in which the animal traps organic material that is floating in the surrounding water
Filter feeding

10. Within the body wall of a sponge, a specialized cell that crawls about and delivers nutrients from the choanocytes to the rest of the body cells
Amoebocyte

11. An asexual reproductive structure produced by some freshwater sponges
Gemmule

12. The regrowth of missing tissues or organs
Regeneration

13. An organism that has both male and female reproductive organs
Hermaphrodite

14. A free-swimming, jellyfish-like and often umbrella-shaped sexual stage in the life cycle of a cnidarian; also a jellyfish or a hydra
Medusa

15. A form of a cnidarian that has a cylindrical, hollow body and that is usually attached to a rock or to another object
Polyp

16. The outer surface layer of cells of a plant or animal
Epidermis

17. In cnidarians, the layer of cells surrounding the digestive tract
Gastrodermis

18. In cnidarians, the jellylike material located between the ectoderm and the endoderm
Mesoglea

19. Gastrovascular cavity
A cavity that serves both digestive and circulatory purposes in some cnidarians
Gastrovascular cavity

20. A flexible appendage with which an animal feeds itself, grasps objects, or feels its environment
Tentacle

21. A stinging cell of a cnidarian
Cnidocyte

22. In cnidarians, a stinging cell that is used to inject a toxin into prey
Nematocyst

23. In cnidarians, a network of nerve cells that lacks a central control; impulses pass in any or all directions to produce a generalized response
Nerve net

24. The free-swimming, ciliated larva of a cnidarian
Planula

25. A limestone ridge found in tropical climates and composed of coral fragments that are deposited around organic remains
Coral reef

26. A cell that is found on the tentacles of a ctenophore and that secretes a sticky substance
Colloblast

27. In ctenophores, a sensory structure that enables the animal to sense its orientation in water; in annelids, a ciliated plate located at the back of the larva
Apical organ

28. The production of light by means of a chemical reaction in an organism
Bioluminescence