Animal Classification

2. An ectothermic vertebrate that usually lives in water when young and on land and as an adult.
5. One of a group of animals with soft bodies and usually a shell, including snails octopuses, and clams.
8. A mammal with a pouch in which to raise its young.
10. One of a group of animals with spiny skin, including sea stars, sea urchins, and sea cucumbers.
11. One of a large group of animals with jointed appendages and exoskeleton.
12. A living internal support structure.
13. An animal that has a backbone.
14. One of a group of animals with no symmetry, cephalization, or gut.
15. The effort to define the boundaries between the various created kinds of animals.

1. A mammal that provides its embryo with oxygen and food through a structure called the placenta
3. A flexible rod that develops into part of the spinal column.
4. A support structure on the outside of the animal's body.
6. The property of an object that means that it can be divided by one or more imaginary lines into mirror-image halves.
7. One of a group of animals with stinging cells, called cnidocytes, including jellyfish.
9. An animal that lacks a backbone.
10. An animal that can regulate its internal body temperature.