Across
- 2. the act of shedding an outer layer, such as feathers, skin, or an exoskeleton, as an animal grows larger
- 4. describes a species that has died out completely
- 6. having openings that liquids or gases can pass through
- 9. a type of snake that wraps around and compresses its prey
- 12. an aquatic vertebrate that is covered in scales, usually has fins, is ectothermic, and breathes oxygen through gills
- 13. relating to a 24-hr rhythm or cycle; animals that are most active during the day
Down
- 1. relating to the night; animals that are most active at night
- 3. an animal having vertebrae or backbones
- 5. a toxin capable of causing injury or death through injection into prey
- 7. an animal that depends on external sources for its body heat
- 8. vertebrate that has wet skin, can live in water or on land, is ectothermic, and typically breathes oxygen through its skin, gills when young, and lungs as an adult
- 10. allowing certain substances to pass through
- 11. vertebrate that has scaly skin, is ectothermic, breathes oxygen using lungs, and lays eggs