This is SeaTalk: Ocean News from the University of Delaware.

Spotting Great Blue Herons hunting in a winter marsh can be shiver inducing. How do the stately wading birds deal with the frigid water temperatures?

The secret to hunting all day in ice-cold water is in a heron’s long, skinny legs. Arteries on the inside of the leg carry warm blood from the body down to the feet. Running next to these arteries are veins that carry cold blood from the feet back up to the body. The heat from the arteries transfers to the chilled blood, warming it before it re-enters the body in a process called countercurrent exchange. This adaptation allows herons to conserve energy in chilly winter waters.

This is SeaTalk, a public service announcement from the University of Delaware, the Delaware Sea Grant College Program, and this station.