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.

Source: Phys.org