Vertebrates
Across
2. Upper shell or case of turtles
6. Bones in birds that make them lightweight
7. Group of extinct reptiles
10. Symmetry of vertebrates
14. Jaws are modified from these
15. Skull case
17. Produced by mammary glands
21. Surface of the nerve chord in vertebrates
22. Pouched mammals like kangaroos
24. Animal with a backbone
27. Birds that hatch helpless
30. Having an anterior or head end with sense organism
32. Cartilaginous fish with wing like pectoral fins
33. Respiratory structures of terrestrial vertebrates
35. Sharks, rays, and skates
39. Egg layers like reptiles and birds
41. Soft insulating feathers on birds
42. Flexible rod sometimes replaced by the backbone
43. Regulate body temperature to the environment
44. Texture of the shell of a reptile
45. Egg laying mammals
Down
1. Characteristic unique to birds
3. Tail fin on fish
4. Collecting chamber in birds and reptiles for wastes
5. Air filled sac in fish that help maintain buoyancy
8. Bony covering over the gills on fish
9. Organ in the roof of the mouth of reptiles to detect heat and chemicals
11. Excretory structures in vertebrates
12. All aquatic group of vertebrates with gills, fins, and scales
13. Replaces teeth in birds
16. Terrestrial vertebrate that returns to the water to reproduce
18. Number of heart chambers in birds and mammals
19. Keeping their skin this way lets amphibians breathe in oxygen through the skin
20. Characteristic unique to mammals
23. Row of chemical receptors on the side of fish to detect changes in vibrations
25. Number of heart chambers in amphibians and most reptiles
26. Skeleton in vertebrates
28. Third eyelid on frogs
29. Sharp pointed teeth or fangs in carnivorous mammals
31. Scales on sharks
34. Respiratory structures for aquatic vertebrates
36. Number of heart chambers in fish
37. Regulate body temperature through their metabolism
38. Eel like, jawless, predatory fish with a sucker type mouth
40. Bony fish