Cartilaginous fish, like sharks and rays, breathe using a system of gills located on the sides of their heads.
Gills: The Breathing Apparatus
These fish have five to seven pairs of gills. Unlike bony fish, cartilaginous fish do not have an operculum (a bony plate) covering their gills.
How Gills Work
The gills are responsible for the crucial gas exchange necessary for survival. Here's a breakdown:
- Water Intake: The fish takes in water through its mouth.
- Water Flow: The water then flows over the gills.
- Oxygen Absorption: As water flows over the gills, specialized structures extract oxygen from the water.
- Carbon Dioxide Release: At the same time, carbon dioxide, a waste product of respiration, is released from the fish's blood into the water.
- Water Exits: The water, now depleted of oxygen and carrying carbon dioxide, exits through the gill slits.
Key Points
| Feature | Description |
|---|---|
| Gills | 5-7 pairs located on the sides of the head |
| Operculum | Absent in cartilaginous fish (present in bony fish) |
| Mechanism | Water flows over gills, enabling oxygen intake and carbon dioxide release |
| Examples | Sharks and rays |
This continuous flow of water over the gills ensures a constant supply of oxygen to the fish's bloodstream and the removal of carbon dioxide.
