What Is the Function of the Spiracle in Sharks?

Spiracles on sharks are small holes that are located behind each eye that opens into the mouth and act in much the same way as a gill opening. These gills draw in oxygenated water from above and aid in breathing even when the shark is on the bottom of the ocean.

The spiracle is located in the majority of all sharks with the exception of the requiem shark, the hammerhead shark and chimaeras. It can also be found in some of the most primitive bony fish, including the sturgeon, paddle fish, bichirs and coelacanth. The spiracle is thought to be associated with the ear opening in frogs.