- Most sharks breathe by swimming with their mouths open so water passes over their gills.

- Water comes into the shark's mouth and passes over its gills, where oxygen from the water is transferred to the shark's bloodstream.

- The gray reef shark rests by holding very still in caves and crevices.

- Because they're not actively swimming, scientists thought they weren't able to breathe.

Researchers discovered:

- Gray reef sharks actively pump water through their gills while keeping still in caves.

- They do not breathe the same way while swimming.

- The sharks use a buccal pump, located next to their brains.

- Buccal pumps are muscles that inflate the mouth, sucking in water.

- When relaxed, the buccal pump muscles contract, pushing water over the gills.

Sharks are dynamic and interesting creatures.

- They continue to teach scientists new things about their behavior.

Learn More:

- How Do Sharks Breathe?

- How Sharks Breathe: