The term “plasma bat” refers to vampire bats, a unique group of mammals distinguished by their diet composed entirely of blood, a practice known as hematophagy. Three species exist: the common vampire bat (Desmodus rotundus), the hairy-legged vampire bat (Diphylla ecaudata), and the white-winged vampire bat (Diaemus youngi). These bats are found in tropical and subtropical regions of Central and South America, from Mexico to northern Argentina, central Chile, and southern Uruguay. They are the only mammals that subsist exclusively on blood.
How Vampire Bats Acquire Blood
Vampire bats employ a sophisticated array of sensory abilities to locate their prey, which typically includes sleeping mammals like cows and horses, or birds. They utilize echolocation, emitting high-pitched sounds and interpreting the echoes to determine the location and distance of potential hosts. In addition, these bats possess specialized heat-sensing pit organs near their noses, allowing them to detect variations in body temperature and identify areas where blood flows close to the skin surface.
Once a target is identified, the bat lands on the ground near the resting animal and hops or crawls stealthily towards it. Their strong hind legs and elongated thumb claws enable agile ground movement, a unique adaptation among bats. Upon reaching a suitable spot, the bat uses its razor-sharp incisor teeth to make a small incision, usually 3-5 millimeters wide and deep, in the skin. This incision often goes unnoticed by the host due to the precision of the bite and pain-suppressing compounds in the bat’s saliva.
Following the incision, the bat laps up the blood with its specialized tongue. The tongue has two lateral grooves on its underside that facilitate blood flow into the bat’s mouth through capillary action. This feeding process can last approximately 20 to 30 minutes, during which the bat’s saliva helps maintain blood flow.
Biological Adaptations for a Blood Diet
Vampire bats have evolved numerous biological adaptations for their blood-only diet. Their specialized dentition includes thin, blade-like incisors and canines, which are exceptionally sharp and lack enamel. These allow them to create precise, painless incisions without dulling their edges, contributing to the host’s unawareness.
The saliva of vampire bats contains a unique cocktail of biochemical compounds crucial for successful feeding. One prominent component is Draculin, a glycoprotein that acts as a potent anticoagulant, preventing the prey’s blood from clotting at the wound site and ensuring continuous flow. The saliva also contains pain-suppressing compounds, which help the host remain undisturbed.
Processing a primarily liquid diet presents a significant physiological challenge, as blood is about 78% water. Vampire bats have highly efficient kidneys and a specialized digestive system designed to rapidly process and excrete excess water and urea from ingested blood. A common vampire bat can begin to excrete very dilute urine within two minutes of feeding, allowing it to shed considerable water weight and become light enough to fly back to its roost. The stomach lining quickly absorbs blood plasma, which is then swiftly transported to the kidneys and bladder for excretion.