DIFFERENTIAL NUTRIENT EXTRACTION IN THE FUNNEL-WEB SPIDER AGELENA LABYRINTHICA

Agelena labyrinthica Clerck spiders were raised in the laboratory at t hree diet levels. Growth, reproduction and the pattern of nutrient ext raction of each spider were monitored. The extraction of proteins, car bohydrates and lipids by each spider was analysed on three occasions, covering the immature and mature stages. More nutrients were extracted the less well-fed the spider, and females extracted more nutrients th an did males. Nutrients were extracted most completely during early gr owth and, especially protein, by females in the reproductive phase. Pr otein was extracted more completely than lipids or carbohydrates. The relative amounts of the three nutrients extracted changed significantl y with time, indicating that spiders are able to adjust their detailed feeding behaviour to their immediate needs. Field collections over th e season showed that most spiders in the field grew approximately as t hose on the medium laboratory ration for most of the time.