Animal Crossword Puzzle

3. The stiff covering on the outside of some creatures.
4. A system of vessels in echinoderms containing a circulating watery fluid is used especially for the movement of tentacles and tube feet.
5. An organ that connects the developing fetus to the uterine wall, thereby allowing nutrient uptake,waste elimination, and gas exchange the mother's blood supply.
6. A strong,flexible connective tissue that protects your joints and bones.
9. A projecting mass of swollen and hypertrophied tumorous membrane.
12. Any so-called cold-blooded animal
13. The study of the impact of the indoor environment on our health.
14. The community of organisms that live on, in, or near the bottom of a sea river, lake or stream.
15. Warm-blooded animals
16. The type of egg produced by reptiles,birds,and prototherian egg laying mammals amniotes,in which the embryo develops.
18. Located in the body cavity and is derived from an outpocketing of the digestive tube.
20. Plant and animal symmetry in which similar parts are arranged in a balanced way around the center of the body.
21. An animal lacking a backbone, such as an arthropod, mollusk, coelenterate, etc. The invertebrates constitute an artificial division of the kingdom. an artifcial

1. The property of being symmetrical on either side of a unique plane.
2. Animals that posses a vertebral column and/or notochord at any point in their lives.
7. Lack of equality or equivalence between parts or aspects of something lack of symmetry.
8. A skeleton that is on the inside of a body, like humans,dogs,or some fish.
10. The shedding of the exoskeleton cuticle of the previous life stage.
11. An organism plant or animal having both male and female reproductive organs.
17. A highly evolved and specialized organ present in pairs, one on each side of the anterior chest wall.
19. One of two principal body types occurring in members of the invertebrate animal phylum Cnidaria.