Marine Animals

3. a system of canals in echinoderms containing a circulating watery fluid that is used for the movement of the tentacles and tube feet.
4. An air-breathing egg characterized by a shell and extraembryonic membranes
5. an animal lacking a backbone
6. is an organ that connects the developing fetus to the uterine wall, thereby allowing nutrient uptake, waste elimination, and gas exchange via the mother's blood supply
10. one of two principal body types occurring in members of the invertebrate animal phylum Cnidaria
14. located in the body cavity and is derived from an outpocketing of the digestive tube
15. is a non-vascular type of supporting connective tissue that is found throughout the body
18. any so-called cold-blooded animal
19. opposite sides are similar
21. shed old feathers, hair, or skin, or an old shell, to make way for a new growth

1. Glandular organ located on the chest
2. symmetry around a central axis
7. a chemical reaction that absorbs energy
8. an organism that has both kinds of reproductive organs
9. an extra piece of tissue that grows inside your body
11. lack of symmetry
12. having a vertebrae or backbone
13. is the rigid covering found on the exterior of many animals
16. organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams
17. having or developing buds
20. an internal skeleton, such as the bony or cartilaginous skeleton of vertebrates.