rete

As described in a new paper published in Science, it’s all thanks to specialized networks of blood vessels known as “retia mirabilia.”

Crucially, when blood is pumped into the animal's gills to collect oxygen, heat loss is minimised by a dense, intertwined network of blood vessels called a rete mirabile.

During a dissection, Wegner noticed that the gills were sporting the same kind of blue and red blood vessels, called retia mirabilia, that tuna and sharks use to heat parts of their bodies.

This arrangement of paired arteries and veins is known as a rete mirabile, or “wonderful net,” and often functions as a countercurrent heat exchanger in other species.

This network, called a rete mirabile, was described in the devil rays 30 years ago.