Blood-feeding behavior or hematophagy is an evolutionary behavior found in diverse species across the globe. Blood is an incredibly energy-rich food source, so it makes sense that animals would evolve to be able to consume this. Out of the 1.5 million animal species found worldwide, only a relatively small number, about 30,000 feed exclusively on blood which equates to 2%. These range from small species such as mosquito or leech to lampreys and oxpecker birds.
These animals have all evolved separately to consume blood and use multiple strategies to utilise this food source fully. Primarily, they play host to bacteria who provide nutrients not found in the blood and inject anaesthetics and anticoagulants into their victims to prevent being swatted while feeding. Unfortunately for humans, we share a long and occasionally complicated relationship with these creatures. On the one hand, we regard some of these creatures as pests which annoy us like mosquitoes and on the other hand, we have depended on leeches as a therapeutic tool for years.
Despite our love-hate relationship with such species, humans do possess a deep fear of them stemming from fear of a creature devouring our life force. This is revealed by bloodsucking monsters in folklore such as vampires and the chupacabra. However, most blood-feeding species does not pose a severe threat, but they are vital to the health of our planet, and they contribute to the Earth’s biodiversity.