How animals breathe

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Across
  1. 2. This animals has lungs and lives under water.
  2. 5. people, animals need to do this.
  3. 7. Organ used by aquatic animals for breathing.
Down
  1. 1. Fish breathe here.
  2. 3. Mammals have these to breathe.
  3. 4. Is the system responsible for breathing.
  4. 6. Insects use this to breathe.