Spiders are often solitary animals (some of them are even cannibals that eat their own species, so they tend to stay as far away as possible from each other).
But in the case of Anelosimus eximius spiders, the more, the merrier. Here's why the social spiders prefer social networking by living in giant colonies:
The ability to work together and capture larger prey has allowed social spiders to stretch the laws of nature and reach enormous colony sizes, UBC zoologists have found. [...]
“The size of organisms tends to be constrained by a scaling principle scientists call ‘surface to volume ratio,’” says Leticia Avilés, lead author and associate professor in the UBC Dept. of Zoology. While organisms typically have energetic needs proportional to their volume, they must acquire nutrients through their surface.
“As the organism grows, this surface to volume ratio declines. In a way, this is how nature keeps the sizes of various species in check.”
The same principle may apply to social groups. The surface area of the three-dimensional webs social spiders use to capture prey does not grow as fast as the number of spiders contained in the nests; so number of incoming prey per spider declines with colony size. But Anelosimus eximius, a species of social spider notable for its enormous colony size – some total more than 20,000 individuals – have gained the ability to stretch that law by cooperating and thus capturing increasingly large insects as their colonies grow.
“The average size of the prey captured by the colony increased 20-fold as colony size increased from less than 100 to 10,000 spiders,” says Avilés, who studied the spiders in the wild in Amazonian Ecuador with undergraduate student Eric Yip and graduate student Kimberly Powers.
Previously on Neatorama: Arachnophobia City! Thousands and Thousands of Spiders | Giant Spider Web