The ecological impact of spiders

A light snack

ARACHNOPHOBIA is a common and powerful fear. Spiders sit high in the pantheon of species that have an outsized terror-to-danger ratio. But, unsettling though they may be, the eight-legged do excel at keeping six-limbed pests in check. They prey upon insects in vast quantities, while, for the most part, leaving people alone. Indeed, in 1957 William Bristowe, a British arachnologist, wondered whether British spiders might kill prey equivalent in mass to all of the people then living in Britain.

In research published this week in the Science of Nature, Martin Nyffeler of the University of Basel, in Switzerland, and Klaus Birkhofer of Lund University, in Sweden, attempt to put some numbers on spiders’ dining habits. Starting with the available data on the mass of spiders found per square metre in Earth’s main habitat types—forests, grasslands, fields of crops and so on, they calculated the amount of prey required in each habitat to support the weight of spiders there, based on spiders’ known food requirements per unit of body weight. That done, they extrapolated their habitat-based…Continue reading
Source: Economist