Posted on Apr 15, 2021 124
The smaller is the size of a spider, the bigger is its brain, which makes almost its entire body full of brain and internal organs have to occupy free cavities.
Big brain size is the only reliable explanation how even the tiniest member of the spider family the size of a needle’s eye remembers the technique and pattern of weaving a web. And in this skill tiny spiders are not inferior to their larger counterparts.
How did they find this out?
Smithsonian scientists analyzed about a dozen species of spiders from different families that weave webs. And in the study, it turned out that small spiders had huge brains.
Some species had such a sprawling central nervous system that it took over not only the body but also hollow limbs.
Young specimens often have bulges on their bodies, filled with a brain that has no more space. As the spider grows, there is more space and the bulges disappear.
Spiders that don’t weave webs are also smart.
Given the size and location of a spider’s brain, it’s easy to assume that its intelligence comes with a detriment to other body organs.
Looking at the structure of spiders, it is obvious that they have had to sacrifice a lot to the brain. For example, in every adult of the family of jumping Argentinean spiders, the entire digestive tract was displaced from the torso to the head. At the same time, in baby spiders, the same area is occupied by the brain, due to which the digestive organs are practically not developed. It has not yet been possible to establish the effect of this phenomenon on the health of young individuals.
Some suggest that a large brain resulted from the need to weave a web. This is a distinctive sign of a more complex behavior than, for example, in the larval beetle which feeds on the rot and mold on which it lives. But it turns out that those spiders that have lost the ability to spin webs and simply parasitize by stealing food from their fellows have the same brain size.
Apparently, the ability to be savvy, cautious and inconspicuous requires a lot of intelligence, which may explain the comparable brain size of spiders that steal prey and their congeners, weaving nets.