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How does the rete mirabile help cetaceans during dives?

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Illustration showing various cetaceans, including baleen whales like the blue whale, fin whale, humpback whale, gray whale, sei whale, northern right whale, and bowhead whale, as well as toothed whales such as the sperm whale, narwhal, beluga, Baird's beaked whale, killer whale, dolphins, and porpoises. Each species is labeled with its scientific name and typical or maximum length, with a size scale in the corner for reference. — cetacean Whales (order Cetacea).

The rete mirabile—Latin for "marvelous network"—is a specialized system of blood vessels that serves as a vital reservoir for oxygenated blood in cetaceans.

During a dive, these networks function as bypasses that allow the animal to isolate circulation to its skeletal muscles. By restricting blood flow to these areas, the cetacean can prioritize the delivery of its limited oxygen stores to the heart and brain. Because these two organs require a constant supply of oxygen to survive, this mechanism is essential for sustaining the animal while it is submerged and unable to breathe.12