How Insect Blood Stops Bleeding Fast

taylorvich writes:

https://arstechnica.com/science/2024/04/how-insect-blood-stops-bleeding-fast/

What if human blood turned into a sort of rubbery slime that can bounce back into a wound and stop it from bleeding in record time?

Until now, it was a mystery how hemolymph, or insect blood, was able to clot so quickly outside the body. Researchers from Clemson University have finally figured out how this works through observing caterpillars and cockroaches. By changing its physical properties, the blood of these animals can seal wounds in about a minute because the watery hemolymph that initially bleeds out turns into a viscoelastic substance outside of the body and retracts back to the wound.

"In insects vulnerable to dehydration, the mechanistic reaction of blood after wounding is rapid," the research team said in a study recently published in Frontiers in Soft Matter. "It allows insects to minimize blood loss by sealing the wound and forming primary clots that provide scaffolding for the formation of new tissue."

Hemolymph has a drastically different composition from vertebrate blood. It is devoid of red blood cells and platelets. The cells that make up hemolymph, known as hemocytes, act like white blood cells in vertebrates, carrying out functions such as eating potentially infectious bacteria and helping form clots over wounds. Some insects have blood richer in hemocytes than others. Even the larval forms of certain species may have more hemocytes in their blood than adults, with many adult butterflies and moths having hemocyte-poor hemolymph compared to the caterpillars.

When experimenting with the sphinx moth caterpillars (Manduca sexta), the researchers placed the caterpillar in a hard plastic sleeve with holes and then made an incision in one of its prolegs. The greenish hemolymph that escaped the wound dripped like water for a few seconds. However, it soon thickened into a viscoelastic fluid that dripped much more slowly. Its final drop did not detach and fall but instead retracted toward the wound.

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