Can Spiders Drink Blood?
One of the most common misconceptions about spiders is that they can eat blood. While some insects and animals do suck blood from other creatures, it is unlikely that spiders are capable of doing this. The truth is, spiders do not have an open circulatory system, which means that they do not have a system of veins for delivering oxygen to their bodies. They instead rely on other forms of food.
In fact, spiders are capable of liquefying prey using digestive enzymes. This process is called pinocytosis. Once the prey has been liquefied, the digesting spider pumps digestive fluids into the prey.
Spiders also regurgitate the liquefied prey mixture in order to maximise digestion efficiency. For this reason, they prefer to ingest prey that is blood-fed, compared to prey that is fed on sugar.
To investigate the preference of spiders for blood-fed mosquitoes, Dr Ximena Nelson and her team at Macquarie University in Australia performed a series of tests. Their results showed that 162 out of the 477 test spiders preferred blood-fed female mosquitoes. These spiders were raised in a lab and were drawn to the mosquitoes’ scent and blood.
The testing period lasted 30 minutes. Each of the spiders was introduced to a test chamber and held in a vial. Some were placed for only a few seconds, while others were left in the vial for five minutes.
The tests showed that the spiders stayed in the vial for longer periods of time than those that were placed for a few seconds. Therefore, the longer the spiders stayed in the vial, the more likely they were to be considered a favorite.