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Across 1. these glands allow for a class of chordates to provide nutrients for their young 5. this type of egg allows for reproduction that does not involve water 8. animals in this class are often called jawless fish 10. the most abundant group of mammals 11. invertebrate chordates that are small fish-like creatures with definite heads 12. animals in this class are known for their tough skin 13. protects the outside body found on insects and crustatians 17. these feathers cover most of the wings and are stiff also known as flight feathers 21. embryos are nourished directly by the mother before birth 23. cold blooded 25. these fish lay eggs 26. these feathers are soft short and fluffy and provide insulation 27. fish included in this class are largely built from cartilage instead of bone 28. pouched mammals

Down 2. this class is most known as being able to fly 3. most animals in this class are covered with hair and are live born 4. this muscular wall in birds grinds gravel and food making easier to digest 6. egg laying mammals 7. this type of tail can be used for grasping while climbing 9. invertebrate chordates they get their name from a special body covering 14. eggs develop inside the female and are nourished with a yolk sack 15. an enlarged area where food can be stored in birds 16. animals in this class live on the land and in the water 17. a supporting marital more flexible than bone 18. warm blooded 19. wear skin over their skeletons 20. flexible rod structure that preceded backbones 22. fish in this class have complete bones used for the skeleton 24. these feathers repel water