Water as an Essential Resource: Orb Web Spiders Cannot Balance Their Water Budget by Prey Alone

Abstract

Water is essential for all living organisms because it acts as a major solvent and reaction medium. Terrestrial animals may lose water through evaporation and excretion and consequently have evolved strategies to balance their water budget by either minimising losses or by gaining water. The major pathway to gain water is via food intake, although many animals additionally drink free water. Spiders acquire substantial amounts of water by ingesting enzymatically liquefied prey. However, this may not account for the water needs of some species. We tested whether drinking is essential for orb web spiders of the genus Argiope by experimentally manipulating the diet (flies or crickets) and water supply (no water or a daily shower) to females and then measuring their subsequent drinking behaviour. Individuals of Argiope trifasciata, which are typically found in dry habitats, increased their body mass when fed crickets but not when fed flies. However, spiders deprived of water subsequently ingested significantly more water than spiders that received water every day, regardless of their feeding regime. This pattern was replicated in Argiope aetherea, which is found in the tropics and perhaps less likely to be water deprived in natural populations. Our results reveal that drinking allows these spiders to realise their water balance independent from the nutritional status. We suggest that the spiders may need to drink fresh water to process ingested nutrients.

Chronic exposure to soil salinity in terrestrial species: Does plasticity and underlying physiology differ among specialized ground-dwelling spiders?

“…Moloney & Nicolson (1984) showed that loss of water the middle shore living spider Desis formidabilis was higher than that of Amaurobioides africanus, which lives at higher elevations in the shore. We did not report such a difference in the spatial distribution of A. fulvolineata and P. purbeckensis, and, alternatively differential respiration and excretion losses (Walter et al 2012) could explain the distinct body water patterns between these two salt-marsh spider pecies.…”

System Dynamics Model for Evaluating Socio-Economic Impacts of Different Water Diversion Quantity from Transboundary River Basins—A Case Study of Xinjiang

“…Water resources, as one of the natural resources that human society depends on, constitute an irreplaceable foundation of socio-economic development [1]. The demand for water resources increases with the rapid development of contemporary society, which leads to the increasingly prominent conflict between the supply and demand gap of global freshwater resources [2,3].…”

“…From the existing research, to our knowledge, there are still three important gaps: (1) the studies that have been performed on coordinate relationship between water resources and socio-economic sustainable development have focused nearly exclusively on inland rivers, urban lakes and corresponding administrative regions, and no specific analysis has been conducted on transboundary river basins and areas along them. (2) The above research on the relationship between water resources and economic development are all about evaluating WRCC, not considering inter-regional water diversion and the relationships between water diversion regions.…”

Modeling the integrated framework of complex water resources system considering economic development, ecological protection, and food production: A practical tool for water management

“…The rapid increase of the global population, urbanization, and economic development is accelerating the consumption of various natural resources (Zhang et al, 2018;Luo and Zuo, 2019). As one of the most important 30 natural resources, water resources play an indispensable role in socio-economic development and food productivity, which is the fundamental condition of people's lives (Walter et al, 2012;Yang et al, 2019). Recently, the accelerated consumption of water resources impacted by human beings makes it vulnerable to ecological protection (Bei et al, 2009;Yang et al, 2019;Tan et al, 2019).…”