Similar to the fictional character Dracula and the real blood-sucking bats, these jumping spiders in East Africa have a thirst for human blood.
The spider species, Evarcha culicivora, cannot pierce skin and suck blood; instead, they indirectly absorb human blood by choosing female mosquitoes that are full of their victims’ blood.
This bloodthirsty spider is the first known carnivore to select prey based on what the prey has eaten. Blood is a nutrient-rich drink that can be easily absorbed. “Perhaps blood is a readily available liquid meal, nutrient-rich, requiring the least energy to process,” said Ximena Nelson, the study’s author.
Nelson, a scientist at Macquarie University in Australia, and her team conducted experiments on the Evarcha culicivora species. They first placed the spider in a small glass jar so it could not distinguish the scents of various prey – including non-blood-sucking male mosquitoes, sugar-water-drinking female mosquitoes, and blood-feeding female mosquitoes.
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Evarcha culicivora with its “meal” |
Just by sight, the spider consistently chose the blood-filled female mosquitoes – which appeared plump and red.
Next, the researchers infused the scent of mosquitoes into the spider’s enclosure. The spider relied solely on its weak sense of smell to identify the right blood-fed female mosquito.
Nelson noted that blood-sucking is a hazardous activity, thus this spider has learned to minimize danger.
“The subjects that get bitten will have a reflex to swat back, like a human using their hands, while an animal may use its tail – usually resulting in the insect’s death,” Nelson explained. “The Evarcha spider may be safer obtaining blood by killing the mosquito, as the risk of retaliation is less dangerous.”
The spider also employs a clever method to catch plump female mosquitoes. It stalks them like a cat hunting a mouse, leaping up or lunging at the mosquito from below before biting down.
M.T. (according to Discovery)
