Spiny dogfish blood contains a hormone long thought absent in sharks

New evidence of cortisol in sharks challenges 60-year-old belief

A new study detected cortisol in shark blood challenging a decades-old assumption that sharks and rays cannot produce the hormone

Spiny dogfish blood contains a hormone long thought absent in sharks

Cortisol is a hormone that helps humans and many other animals regulate their energy use and respond to changing conditions. For a long time, sharks and rays were believed to rely on a different steroid hormone for these functions, without producing cortisol themselves. Now, a new study of North Pacific spiny dogfish, a species of small shark, challenges this view.