African lungfish (Protopterus spp.) live in water for part of each year. During yearly dry seasons, though, they dig into mud, curl up, and secrete staggering amounts of mucus that then hardens to form a cocoon of protection. This process, known as estivation, allows the animals to survive on land for years, protecting them from complete desiccation until water returns, at which point they rehydrate their bodies and go back to swimming. Most scientists believed the cocoon to be inert, but a study in Science Advances suggests otherwise. The authors found that the mucus cocoon is filled with white blood cells called granulocytes, which create extracellular traps to nab bacteria and protect the animals from sepsis, skin infections, and blood loss.
“This is an animal that, for this brief moment in time, can—like a force field—extend its body, its actual living body beyond its scope,” says Ashley Poust, a vertebrate ...
