Hammerhead Sharks Hold their Breath on Deep Water Hunts to Stay Warm
Published:28 May2023    Source:University of Hawaii at Manoa

Scalloped hammerhead sharks hold their breath to keep their bodies warm during deep dives into cold water where they hunt prey such as deep sea squids. This discovery, published today in Science by University of Hawai'i at Manoa researchers, provides important new insights into the physiology and ecology of a species that serves as an important link between the deep and shallow water habitats.

The research team discovered this unexpected phenomenon by equipping deep-diving scalloped hammerhead sharks with devices that simultaneously measured their muscle temperature, depth, body orientation, and activity levels. They saw that their muscles stayed warm throughout their dive into deep cold water but suddenly cooled as the sharks approached the surface toward the end of each dive. Computer modeling suggested that hammerhead sharks must be preventing heat loss from their gills to keep their bodies warm during these deep-dives into cold water.
"This new and detailed understanding of scalloped hammerhead physiology and ecology enhances our ability to effectively manage and conserve this iconic species by revealing potential vulnerabilities associated with changing ocean conditions or future human exploitation of these deep foraging habitats, such as deep-sea mining or large-scale fishing in the mesopelagic "twilight zone," both of which might make it harder or more dangerous for these sharks to hunt their natural prey," said Royer. "This extraordinary physiological feat that allows scalloped hammerhead sharks to expand their ecological niche into the deep sea could very well make them vulnerable to additional human impacts."