1. Water Intake: Great white sharks open their mouths and swim forward to take in water. They actively pump water into their mouths through a process known as "ram ventilation."
2. Gill Structure: The inside of a shark's mouth is covered in multiple gill slits. Each gill slit contains several thin, feathery structures called gill filaments. These filaments increase the surface area available for gas exchange.
3. Cellular Exchange: As water passes over the gill filaments, oxygen in the water diffuses into the blood vessels within the filaments. Simultaneously, carbon dioxide, a waste product of cellular respiration, diffuses out of the blood and into the water. This exchange of gases occurs due to concentration gradients, with oxygen moving from an area of higher concentration in the water to an area of lower concentration in the blood, and carbon dioxide moving in the opposite direction.
4. Water Expulsion: After the exchange of gases, the used water is expelled through the gill slits on the sides of the shark's head. The shark can control the opening and closing of its gill slits using muscles.
5. Buccal Pumping: Great white sharks also use buccal pumping to assist with respiration. Buccal pumping involves opening and closing the mouth to force water over the gills. This action generates additional flow of water across the gill filaments and helps maintain a steady supply of oxygen.
6. Countercurrent Exchange System: The blood circulation in sharks is adapted for efficient oxygen extraction from water. The blood vessels that carry oxygen-poor blood to the gills run in close proximity to the blood vessels that carry oxygen-rich blood away from the gills. This countercurrent exchange system maximizes the gradient for oxygen diffusion, ensuring that the blood leaving the gills is highly oxygenated.
Great white sharks are capable of closing their gill slits when attacking or biting prey. This prevents water from entering the gills, which could potentially harm the shark or interfere with its feeding behavior. The ability to close the gill slits is an important adaptation that allows great white sharks to hunt effectively.
Overall, great white sharks rely on their gills to breathe, utilizing a combination of ram ventilation, gill structure, cellular exchange, and buccal pumping to efficiently extract oxygen from water. This respiratory system allows them to maintain high levels of activity and perform powerful swimming and hunting behaviors.