Today's Science reveals for the first time: a mysterious network of blood vessels that protects the whale's brain from damage

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In the long evolutionary history, the ancestors of cetaceans have experienced a period of landing, and then returned to the ocean again
.

The shades of yellow in the video reflect changes in internal pressure as dolphins (belonging to cetaceans) swim (video source: Margo Lillie)
In fact, scientists have observed similar pulses in terrestrial mammals such as horses, and explain why
.

Horses also experience blood pressure pulsations as they run, and their coping strategy is to adjust the impulses by exhaling and inhaling to avoid injury
.


However, cetaceans hold their breath as they swim, so this protective mechanism does not apply to cetaceans
.


Now, a new study published in the journal Science has unveiled this mysterious mechanism: a network of blood vessels, the retia mirabilia (also known as the "strange web"), protects the brain and allows cetaceans to swim smoothly in the ocean
.


▲ The blood vessel structure that supplies blood to the spine and brain of cetaceans (Image source: Reference[1]) The research team from the University of British Columbia explored the role of
the labyrinth in this process.

Unlike large numbers of terrestrial mammals, cetaceans have a large distribution of blood vessels in the chest, spine, and cranial region, but their function is unclear
.


Based on the morphology of 11 cetaceans, the research team established a hemodynamic model
of the labyrinth.

The model points out that the huge arterial volume of the labyrinth, as well as the small extravascular volume in the skull and spinal canal, together protect the brain's complex vascular system from differences in
blood pressure.

It is this "pulse-transfer" mechanism that ensures the stability of blood pressure in the brain without lowering the
blood pressure pulse.
The model shows the distribution of arteries in the cetacean spine (Credit: Wayne Vogl)
As a result, the study found that cetacean mesh has a previously unknown function, which may explain why the mesh is missing
in other aquatic vertebrates.


"Our simulations support our hypothesis that the blood pressure pulses generated by exercise can be synchronized with the pulse-transfer mechanism that reduces the impact on cetacean blood pressure by 97 percent
.
"
Professor Robert Shadwick, one of the paper's authors, said
.

As for the next step of the study, another author, Professor Wayne Vogl, said: "It will be important
to understand how cetaceans' chests respond to water pressure deep down and how the lungs affect blood pressure.

[
1] M.
A.
Lillie et al.
Retia mirabilia: Protecting the cetacean brain from locomotion-generated blood pressure pulses.
Science (2022).
https://doi.
org/10.
1126/science.
abn3315[2] Why whales don’t get brain damage when they swim.
Retrieved Sep.
22, 2022 from How the “wonderful net” of cerebral vasculature protects cetacean the brain from swimming-generated pulses in blood pressure.
Retrieved Sep.
22, 2022 from