Factors influencing the evolution of social behaviour in Australian crab spiders (Araneae: Thomisidae)

The social Diaea are non-territorial, periodically-social spiders that do not weave a snare web, a factor considered to be important in spider sociality. Maternal care and heritable retreats are factors common to most group living animals, including social Diaea; suggesting that they are important factors in the evolution of spider sociality. A 4 year survey, along with field and laboratory experiments revealed that mother spiders provided crucial care in the form of a protective Eucalyptus leaf nest and large prey for their offspring. After the mother's death, the nest was inherited and expanded by the offspring. Larger groups built larger, more protective nests, but expended less individual effort doing so, and so survived better than smaller groups.