1. Fish: Fish, such as salmon, trout, tuna, and catfish, have gills to extract oxygen from water. Their gills are located on either side of their heads and consist of thin filaments that increase the surface area for gas exchange.
2. Amphibians: Aquatic amphibians, such as tadpoles and certain species of salamanders and newts, also breathe through gills during their larval stage. As adults, some amphibians may develop lungs, but they retain their ability to breathe through their gills.
3. Mollusks: Many mollusks, including clams, mussels, and oysters, use gills for respiration. Their gills are located within their shells and are made up of delicate tissue that allows water to flow through and exchange oxygen and carbon dioxide.
4. Crustaceans: Aquatic crustaceans, such as shrimp, crabs, and lobsters, have gills for breathing. Their gills are located on the underside of their bodies and are composed of feathery structures that increase the surface area for gas exchange.
5. Echinoderms: Some echinoderms, like sea cucumbers, have gills for respiration. Their gills are located internally and are involved in the exchange of gases with the surrounding water.
6. Polychaetes: Polychaetes, a type of segmented marine worms, also use gills for breathing. Their gills are located along their bodies and are often branched or feathery in appearance.
These are just a few examples of the many aquatic animals that breathe through gills. Gills are essential adaptations that allow these organisms to extract oxygen from water and survive in aquatic environments.