1. Fish:
- Fish breathe through gills, which are feathery structures located on either side of their heads.
- As water passes over the gills, oxygen from the water diffuses into the blood vessels within the gills, and carbon dioxide diffuses out.
- The oxygenated blood is then pumped throughout the body, while the deoxygenated blood returns to the gills to pick up more oxygen.
2. Insects:
- Insects breathe through a network of tiny tubes called tracheae that branch throughout their bodies.
- Air enters the tracheae through small openings called spiracles located along the sides of their bodies.
- As air passes through the tracheae, oxygen diffuses into the surrounding tissues, and carbon dioxide diffuses out.
3. Certain Amphibians:
- Some amphibians, like frogs and salamanders, have both lungs and skin that can absorb oxygen.
- While on land, they breathe primarily through their lungs, which are similar to those of mammals.
- When in water, they can also absorb oxygen through their skin, which is highly vascularized and allows for efficient diffusion of gases.
These specialized respiratory structures allow animals to efficiently extract oxygen from the air and transport it throughout their bodies to support their metabolic processes.