Hold on! - Hammerhead shark
©2023 Pam Ferris-Olson
Hold on! - Sharks belong to a group of fish known as Chondrichthyes or fish that have cartilaginous skeletons rather than bony ones. Rays, skates, and sawfish also belong to this group.
Sharks, like most fish, have gills. As the shark swims, water enters the mouth and passes over the gills. This organ extracts oxygen from the surrounding water.
Gills also are involved in heat transfer, a problem if sharks swim in cold water. Unlike mammals, a shark’s body temperature is determined by the temperature of the water around them. So how do hammerhead sharks stay warm at the cold depths of 500 to 1000m where squid, their preferred prey dwell?
Studies have shown that hammerhead sharks do something like holding their breath When the gill slits and mouth are closed the chance for body heat loss is reduced. As the shark ascends toward the warmer waters at the surface, the gill slits are opened. Once more the blood can be oxygenated without dropping the animal’s body temperature.