* Pumps blood in a single circuit: The fish heart only pumps blood through one circuit, meaning it travels from the heart to the gills, then to the rest of the body, and back to the heart.
* Oxygenates blood: The blood picks up oxygen from the gills and delivers it to the body's tissues.
* Removes carbon dioxide: The blood picks up carbon dioxide from the body's tissues and delivers it to the gills to be expelled.
* Maintains blood pressure: The fish heart, like any heart, maintains sufficient blood pressure to ensure blood flow throughout the body.
Structure:
The fish heart is a two-chambered organ consisting of:
* Atrium: The atrium receives deoxygenated blood from the body.
* Ventricle: The ventricle pumps the deoxygenated blood to the gills.
How it works:
1. Deoxygenated blood enters the atrium.
2. The atrium contracts, pushing blood into the ventricle.
3. The ventricle contracts, pumping blood to the gills.
4. In the gills, the blood picks up oxygen and releases carbon dioxide.
5. Oxygenated blood flows through the body.
6. Deoxygenated blood returns to the heart, starting the cycle again.
This simple system allows fish to survive underwater, where oxygen is scarce compared to air.