Language
Country/Area
No result found
The secrets of social spiders: Why do they choose to live in groups rather than alone?
Among the mysteries of nature, spiders are known for their unique way of survival. Most spiders are solitary and aggressive creatures, however, a subset of species, known as social spiders, choose to live in groups. The spiders' social living not only changes the way they hunt, but also brings many other survival advantages.
Some social spiders aggregate in ways that efficiently maximize the biomass of their catch per individual spider.
Social spiders live primarily in tropical regions, where insects are most abundant in size and numbers. Nevertheless, some species have expanded into the eastern United States and other temperate regions. By building a common web, these spiders are able to cooperate in catching larger prey, even creatures larger than themselves, such as birds and bats. This teamwork hunting method shows the survival wisdom of social spiders.
Beyond this, living in groups offers other important benefits. First, social spiders' nests no longer rely on the maintenance of a single member, which reduces the investment required by each spider to maintain the nest. In addition, having more members in the group means that their defense capabilities against natural enemies are stronger. This is reminiscent of the group behavior of fish and mammals, both of which are designed to jointly resist predators.
Sociality of social spiders
Social spiders exhibit varying degrees of sociality, which can be divided into six categories. Research suggests spiders may have evolved to become social creatures independently 18 or 19 times. Most social spiders fall into the definition of "parasocial", meaning they exhibit communal parenting, use of the same nest (web), and some generational overlap.
In some species, social displays can vary between environments, demonstrating flexible adaptive abilities.
Of the 45,000 known species of spiders, 23 are considered parasocial, distributed across 11 genera and eight different families. The degree of sociality not only varies between species, but can also vary within the same species depending on the environment. This flexible social structure allows them to survive adverse conditions, and parts of the group may return to solitary living when large gatherings are no longer feasible.
Take Anelosimus eximius as an example, the number of its gathering can reach 50,000. All American species of this genus are social, and some Malagasy species also show tendencies towards social behavior. Remarkably, even among social spiders, there are individual species, such as Theridion nigroannulatum, that are able to form colonies of thousands of individuals that work together to capture prey and share food.
Social and semisocial behavior
In addition to overtly social behaviors, there are many spider species that are known to be semi-social. These species usually do not have a fixed social organization and may only display social behaviors during certain seasons, remaining solitary at other times. Some spiders establish their own territories within the group, and in some cases even have independent webs. Although such behavior is not completely cooperative, it is an important cornerstone of social evolution.
Research has suggested that social spiders evolved from solitary, semisocial ancestors.
This transition from solitary to social life provides a deeper understanding of the evolution of sociality in spiders. Semisocial spiders such as Stegodyphus not only show low levels of inbreeding, but also experience minimal inbreeding stress, which means they may have played a key role in the evolution of social spiders.
Migratory behavior of social spidersCertain social spiders, such as Parasteatoda wau and Anelosimus eximius, exhibit migratory behavior similar to that of social insects such as ants and bees. These spiders engage in coordinated migrations among adult and subadult females to find new nesting sites and establish new colonies. This pattern also shows their high inbreeding characteristics, which further reduces their genetic variation due to the restrictions imposed by migration between females.
In many species, female spiders can outnumber males by up to 10 to one, exacerbating the genetic bottleneck.
The evolution of social spiders reveals the delicate balance between cooperation and loneliness in nature. Even in species that appear to be primarily aggressive and solitary, it is possible to find traces of sociality, which makes us wonder: what does the choice between sociality and loneliness reflect from a survival perspective? What kind of ecological wisdom?
