Fish breathe underwater using specialized organs called gills. Here's how the process works:
- Fish take water in through their mouths.
- The water flows over the gills, which are located behind a protective covering called the operculum.
- Gills have thin filaments with many tiny blood vessels and structures called lamellae that increase surface area for gas exchange.
- As water passes over the gills, oxygen dissolved in the water diffuses into the fish's blood through these lamellae.
- Blood flows in the opposite direction to the water flow in a countercurrent exchange system, which maximizes oxygen absorption.
- Oxygen-rich blood is then circulated to the rest of the fish's body.
- At the same time, carbon dioxide and other waste gases diffuse from the blood into the water, which exits the gills.
Fish do not breathe air like humans but extract oxygen from water efficiently through this system.
