Ecology
Horse spiders, often referred to as vampire spiders, have a very peculiar diet: they eat female mosquitoes, which in turn feed on blood. In the course of new research, scientists made the so-called “Frankenstein mosquito”, which consisted of glued parts of different mosquitoes. It turned out that spiders pay attention not only to the blood-red bellies of mosquitoes, but also to female antennas when choosing a victim to attack.
In the past, scientists believed that horse spiders respond to the most basic stimuli that make them hunt. For example, if they see a small moving object, they treat it as prey and attack, says Ximena Nelson of the University of Canterbury, New Zealand.
New research has shown that these spiders are more picky about food choices than previously thought. For example, the E. culicivora horse spider does not use such basic incentives at all, and its prey selection criteria are much more complicated, Nelson said.
A picky eater
The horse spider's favorite dish is blood-filled mosquitoes, or rather mosquitoes. As it turns out, spiders also need fresh blood to survive, scientists say, which is why they dubbed him “vampire”.
Other prey for these spiders are not so attractive, perhaps because they don't feed on vertebrate blood. Blood is an essential part of this spider's diet, although researchers aren't exactly sure why.
On the shores of Lake Victoria in Sub-Saharan Africa, spiders hunt down mosquitoes until they come within 2-3 centimeters of them, then rush at their prey. The youngest spiders can throw themselves at mosquitoes and bite them in flight. They fall to the ground with the victim and then eat the prey.
Search for female mosquitoes
Since only female mosquitoes feed on blood, spiders need to learn to distinguish them from males when hunting. Female mosquitoes differ in appearance from males.
“A person who knows these differences and has good eyesight can easily distinguish female mosquitoes from males. To do this, just look at the “fluffiness” of the insect's antennas,” Nelson says. “Males have more bristles on their antennas, so they look more “shaggy”.
It is possible that spiders also notice a swollen red belly, which only occurs in females who have recently eaten blood.
In order to understand exactly what features of the appearance of mosquitoes spiders pay attention to when choosing a target, scientists created the Frankenstein mosquito, which consisted of different body parts of males and females ( for example, the head and chest of one, the abdomen of the other).
They showed these strange creatures to spiders to see how they would react. Scientists have noticed that two parts of the mosquito's body play the most important role in choosing food in this case: a large red belly and an antenna. Spiders were less likely to attack mosquitoes with furry antennas than with simpler “hats,” even if both had swollen red bellies, studies have shown.