Biology

3. an animal that develops from two separate embryonic germ layers
4. The internal body cavity seen in arthropods
6. a rigid external covering for the body in some invertebrate animals, especially arthropods, providing both support and protection
8. made classification
9. a series of separate bones that surround the spinal cords in vertebrates
12. a phylum of deuterostomes with spiny skin; exclusively marine organisms
14. The layer of cells that lines the outer surface of an animal
15. an air-filled bone
17. the layer of cells that lines the gastrovascular cavity of cnidarians
19. frogs, salamanders, and caecilians
22. Having no plane of symmetry
24. An animal that does not have a backbone
26. a system in echinoderms in which water is the circulatory fluid

1. a fused head and thorax
2. the central cavity bounded by the gastrodermis in cnidarians
5. the shape and symmetry of an organism
7. an amoeba-like cell of sponges whose functions include distribution of nutrients to other cells in the sponge
10. specialized gills in mollusks
11. a typos of symmetry where there is only one plane of symmetry that creates two mirror-image sides
13. Having two genders
16. An animal that has a backbone
18. a form of asexual reproduction in which a portion of the body of an organism breaks off and develops into a living independent organism; found in plants, sponges, and some other invertebrates
20. a jawed fish
21. humans, monkeys, lemurs, and apes
23. a lined body cavity derived from mesodermal embryonic tissue
25. an internal skeleton, such as the bony or cartilaginous skeleton of vertebrates