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Journal ArticleDOI

Foraging at the thermal limit: burrowing spiders ( Seothyra , Eresidae) in the Namib desert dunes

01 Oct 1990-Oecologia (Springer-Verlag)-Vol. 84, Iss: 4, pp 461-467
TL;DR: The hypothesis that web design and thermoregulatory behaviors enable Seothyra to hunt under extreme thermal conditions is supported, and the range of thermal conditions encountered by spiders, their temperature tolerance and the influence of temperature on foraging activity and prey handling behavior is determined.
Abstract: In the Namib Desert dunes, the web of Seothyra sp. (Eresidae) comprises sticky silk lining the edges of a horizontal mat on the sand surface. The spider sits in a silk-lined burrow attached to the mat. Arthropods become entangled in the sticky silk of the mat and are attacked and pulled into the burrow by the spider. We investigated the influence of sand surface temperature on the activity of spiders during the summer. We determined the range of thermal conditions encountered by spiders, their temperature tolerance and the influence of temperature on foraging activity and prey handling behavior. The environmental temperatures available to Seothyra vary from 17–33° C at the coolest time of day to 33–73° C at the hottest. When prevented from retreating into burrows, spiders showed signs of thermal stress at about 49° C, whereas unrestrained spiders continued to forage at web temperatures above 65° C by moving between the hot surface mat and the cooler burrow. Spiders responded quicker to prey stimuli during the hot hours of the day and completed prey capture sequences in significantly less time at surface temperatures above 49° C than below. Furthermore, captured arthropods succumbed more quickly at high surface temperatures. Our study supports the hypothesis that web design and thermoregulatory behaviors enable Seothyra to hunt under extreme thermal conditions.
Citations
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Journal ArticleDOI
TL;DR: A literature review of previous studies to describe the history of the study of thermal tolerance and show the chronological trends in the use of lethal temperature and critical thermal maximum methods and illustrate the diversity of taxa used in thermal-tolerance studies.
Abstract: We reviewed 725 papers published since Cowles and Bogert's paper on thermal tolerance (R.B. Cowles and C.M. Bogert. 1944. Bull. Am. Mus. Nat. Hist. 83: 261–296) to create a data base of studies tha...

730 citations

Journal ArticleDOI
TL;DR: Evidence for the evolution of silk production and web building as traits in spider phylogeny is explored in a coevolutionary arms race against insects.
Abstract: Spiders’ silks and webs have made it possible for this diverse taxon to occupy a unique niche as the main predator for another, even more diverse taxon, the insects. Indeed, it might well be that the spiders, which are older, were a major force driving the insects into their diversity in a coevolutionary arms race. The spiders’ weapons were their silks and here we explore the evidence for the evolution of silk production and web building as traits in spider phylogeny.

160 citations


Cites background from "Foraging at the thermal limit: burr..."

  • ...It constructs a vertical burrow that opens out at the sand surface into a wide dish containing the horizontal web covered with sand; a pair of pits on either side of the web gives the impression at the desert surface of the footprint of a small antelope (Lubin & Henschel 1990)....

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Journal ArticleDOI
TL;DR: The central Australian ant Melophorus bagoti is active during the hottest periods of the summer day, and is one of the most thermally tolerant animals known, which is unique in its avoidance of "cooler" temperatures.
Abstract: The central Australian ant Melophorus bagoti is active during the hottest periods of the summer day. Despite soil surface temperatures exceeding 70° C and air temperatures at ant height exceeding 50° C, this species did not cease midday activity. Individuals were able to survive 2.5 min under these conditions without thermal respite. During natural foraging activity, however, thermal refuges were used during the hottest times of the day. In the laboratory the ants were found to have a critical thermal maximum (CTMax) of 56.7° C and were able to survive for 1 h at 54° C Peak activity in the field occurred when soil surface temperature was 60° C and air temperatures at ant height and ant body temperatures were both 46° C. Apart from being one of the most thermally tolerant animals known, M. bagoti is unique in its avoidance of "cooler" temperatures. During February and March this species did not begin its daily aboveground activity until the soil surface temperature reached a mean of 56.1° C and the air tem...

139 citations

Journal ArticleDOI
TL;DR: At in situ pressure, shrimps from Menez Gwen and Lucky Strike do not survive temperatures of 39°C, and the `loss of equilibrium' response suggests that their critical thermal maximum, which is similar to those found for another vent shrimp, Rimicaris exoculata, is about 36±1°C for both sites.
Abstract: SUMMARY The shrimp Mirocaris fortunata is a hydrothermal vent species that is found at most vent-sites along the Mid-Atlantic Ridge. This endemic species is found across a hydrothermal gradient, with thermal conditions ranging from 2–9°C in ambient seawater to fairly warm values of about 25°C. We performed in vivo experiments on M. fortunata specimens originating from different sites and depths (850 m to 2300 m), both at atmospheric pressure and in pressurized aquaria, to characterise the upper thermal limits of this species. Atmospheric pressure results show that thermal physiology should be studied at each population9s native pressure. At in situ pressure, shrimps from Menez Gwen (850 m depth) and Lucky Strike (1700 m depth) do not survive temperatures of 39°C, and the `loss of equilibrium9 response suggests that their critical thermal maximum (Ctmax), is about 36±1°C for both sites. This value is similar to those found for another vent shrimp, Rimicaris exoculata, which is thought to be a more temperature-resistant organism, so temperature resistance does not appear to be a crucial factor for explaining differences in distribution of shrimp species in a given vent site. Finally, the data for both vent shrimps are also comparable to those of other non-vent tropical caridean species.

60 citations


Cites background from "Foraging at the thermal limit: burr..."

  • ...300·mg FW) desert spider that continues to hunt at temperatures exceeding 65°C, well above its 49°C Ctmax (Lubin and Henschel, 1990)....

    [...]

Journal ArticleDOI
TL;DR: It is suggested that digestive constraints prevented supplemented spiders from fully utilizing the available prey, and by reducing foraging activities on the surface, spiders in a prey-rich habitat can reduce the risk of predation.
Abstract: We tested the alternative hypotheses that foraging effort will increase (energy maximizer model) or decrease (due to increased costs or risks) when food supply increased, using a Namib desert burrowing spider, Seothyra henscheli (Eresidae), which feeds mainly on ants. The web of S. henscheli has a simple geometrical configuration, comprising a horizontal mat on the sand surface, with a variable number of lobes lined with sticky silk. The sticky silk is renewed daily after being covered by wind-blown sand. In a field experiment, we supplemented the spiders' natural prey with one ant on each day that spiders had active webs and determined the response to an increase in prey. We compared the foraging activity and web geometry of prey-supplemented spiders to non-supplemented controls. We compared the same parameters in fooddeprived and supplemented spiders in captivity. The results support the "costs of foraging" hypothesis. Supplemented spiders reduced their foraging activity and web dimensions. They moulted at least once and grew rapidly, more than doubling their mass in 6 weeks. By contrast, food-deprived spiders increased foraging effort by enlarging the diameter of the capture web. We suggest that digestive constraints prevented supplemented spiders from fully utilizing the available prey. By reducing foraging activities on the surface, spiders in a prey-rich habitat can reduce the risk of predation. However, early maturation resulting from a higher growth rate provides no advantage to S. henscheli owing to the fact that the timing of mating and dispersal are fixed by climatic factors (wind and temperature). Instead, large female body size will increase fitness by increasing the investiment in young during the period of extended maternal care.

56 citations

References
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Journal ArticleDOI
01 Mar 1975-Ecology
TL;DR: Analyses of the movements and web-site characteristics of the desert spider Agelenopsis aperta (Gertsch) demonstrate that web locations offering the following habitat features are actively selected: shrubs, depressions, litter, and flowering herbs.
Abstract: Analyses of the movements and web-site characteristics of the desert spider Agelenopsis aperta (Gertsch) demonstrate that web locations offering the following habitat features are actively selected: shrubs, depressions, litter, and flowering herbs. A model of the effects of the thermal environment and prey avalability on the reproductive success of spiders occupying various web-site types is developed. The estimated productivity for an excel- lent web site (grassland depression with attractants) is 13X that determined for a poor site (lava surface). Model results suggest that more energy is to be obtained from selection of a favorable thermal environment (eight-fold difference) than from a site offering greater num- bers of prey (two-fold difference). The presence of flowers at web sites increases the prob- ability of receiving an occasional high prey density, whereas litter and habitat features pro- viding shade (shrubs and depressions) allow increased spider activity through limitation of body temperature.

265 citations


"Foraging at the thermal limit: burr..." refers background in this paper

  • ...In spiders, high daytime ambient temperatures may restrict the time available for foraging on the surface, thereby influencing growth and reproductive output (Riechert and Tracy 1975)....

    [...]

Book ChapterDOI
TL;DR: Climate plays a critical role in the life of terrestrial insects, and affects their geographical and ecological locations, the site and timing of their activities, the success of oviposition and hatching, and the duration of developmental stages.
Abstract: Publisher Summary Climate plays a critical role in the life of terrestrial insects. It affects their geographical and ecological locations, the site and timing of their activities, the success of oviposition and hatching, and the duration of developmental stages; thus, ultimately it is often a key factor in the selective processes acting on insects, to a far greater extent than for the much larger terrestrial vertebrates. The effects of the physical environment on insects must be mediated through the biochemistry and physiology of the individual—whether as egg, larva or adult—and this is generally expressed via changes in the microenvironment of the fluids in the tissues and cells of the insect upon which basic life processes depend. There is no single optimal solution to the problem of integrating microclimate and physiological functioning; the chosen regimes of humidity, temperature, radiation, and wind are determined both by the intrinsic properties of the species and by the biotic and physical characteristics of available niches and their use by competing species. It might be predicted, for instance, that insects would in general be darker-colored in colder areas, and paler in deserts or the tropics, or that mean sizes of insects would be correlated with climate.

214 citations


"Foraging at the thermal limit: burr..." refers background in this paper

  • ...Arthropod activity is strongly limited by climatic conditions, especially temperature and humidity (Casey 1981 ; Crawford 1981; Willmer 1982)....

    [...]

Journal ArticleDOI
TL;DR: A model is developed to predict the energy costs of foraging and maintenance of an Atta colony and differs significantly from values predicted on the basis of published equations relating Mrun to body mass in vertebrates and insects.
Abstract: Standard rates of O₂ consumption ($\dot{V}O_{2}$) and net, gross, and minimum costs of transport (NCOT, GCOT, and $M_{run}$) were measured in the leaf-cutting ant Atta colombica. Both closed (running wheel respirometer) and flow-through (treadmill) systems were used. The relation between body mass (.004-.035 g) and standard $\dot{V}O_{2}$ in workers was $\dot{V}O_{2} = .074 M^{.62}$ where $\dot{V}O_{2}$ is ml h⁻¹ at 28 C and M is mass in grams. When combined with published data for 30 ant species, at 20 C this equation becomes $\dot{V}O_{2}$ = $.137 M^{.838}$. Equations that allow calculation of NCOT and GCOT from body mass and running speeds are presented. NCOT in A. colombica at 28 C was 18.6 ml O₂ g⁻¹ km⁻¹ (mass .015 g, running speed 5.2 cm s⁻¹). Both NCOT and GCOT decreased with increasing body mass. Load carriage decreased running speed and increased NCOT proportionally to the increase of body mass + load mass. Cost of transporting a unit of load and a unit of body mass were therefore equivalent. $M_...

182 citations

Book
01 Jan 1981
TL;DR: This chapter discusses the evolution and present distribution of Deserts, and the role of Climate and Producers Relative to Invertebrate Habitats and Feeding Patterns, as well as Desert Ecosystems: Consumers.
Abstract: 1 Deserts and Desert Invertebrates.- 1 Perspectives.- A. Evolution and Present Distribution of Deserts.- I. Physical Causes of Deserts.- 1. The Role of Climate.- 2. Classification of Present Deserts Based on Climate.- a. Subtropical Deserts.- b. Continental Interior Deserts.- c. Rain Shadow Deserts.- d. Cool Coastal Deserts.- e. Polar Deserts.- 3. Desertification.- a. Effects of Vegetation Removal.- b. Effects of Withholding Fire.- II. Continental Drift, Paleoclimates, and Desert Evolution.- 1. Gondwanaland and Pangaea.- 2. Mesozoic Events and Aridity.- 3. Desert Formation in the Tertiary.- 4. Quaternary Environments and Modern Deserts.- B. Physical Environment of Deserts.- I. Climate.- 1. Radiant Energy.- 2. Wind.- 3. Water.- II. Surfaces and Soils: Their Properties and Microclimates.- C. Desert Ecosystems: Producers.- I. Introduction.- II. Role of Producers Relative to Arid-Climate Patterns.- 1. Production in Desert Plants.- 2. Production Relative to Major Physical and Climatic Factors.- III. Role of Producers Relative to Invertebrate Habitats and Feeding Patterns.- 1. Trees and Shrubs.- 2. Annuals.- 3. Cryptogams.- D. Desert Ecosystems: Consumers.- I. Introduction.- II. Production, Life History, and Climate.- III. Influence of Consumers on Primary Production.- 2 The Array of Desert Invertebrates.- A. Protozoans.- B. Nematodes.- C. Annelids.- D. Gastropod Mollusks.- E. Isopods and Other Crustaceans.- F. Solifugid Arachnids.- G. Uropygid Arachnids.- H. Pseudoscorpions.- I. Scorpions.- J. Opilionid Arachnids.- K. Spiders.- L. Mites.- M. Millipedes.- N. Centipedes.- O. Entognath Hexapods and Apterygote Insects.- P. Cockroaches and Lesser Orthopteroid Insects.- Q. Locusts and Grasshoppers.- R. Termites.- S. Hemipteroid Insects.- T. Neuropterans.- U. Beetles.- V. Butterflies and Moths.- W. Flies.- X. Bees and Wasps.- Y. Ants.- Z. Fleas.- Summary Comments: Part 1.- 2 Adaptations to Xeric Environments.- 3 The Use of Light and Timing of Activity.- A. Introduction.- I. Photoperiod.- II. Light Intensity and Wavelength.- B. Simple Light Responses and Diel Periodicities of Desert Invertebrates.- I. Mollusks.- II. Isopods.- III. Arachnids.- IV. Myriapods.- V. Insects.- VI. Assessment of Diel Periodicities.- C. Seasonal Periodicities of Desert Invertebrates.- 4 Water Relations: Short-Term Water Balance.- A. Introduction.- B. Water Loss.- C. Water Uptake.- D. Patterns of Desiccation Resistance.- 5 Seasonal Water Relations: Long-Term Water Balance.- A. Introduction.- B. Soil-Associated Invertebrates.- C. Desert Locusts.- D. Summary Comments.- 6 Temperature Relations.- A. Introduction.- B. Thermal Budgets Describing Thermal Balance.- C. Morphological Adaptations.- I. Dead Air Spaces.- II. Limb Length.- III. Color.- IV. Integumental Properties Other than Color.- D. Behavioral and Physiological Adaptations.- I. Behavioral Thermoregulation.- 1. Evaporative Cooling by Behavioral Means.- 2. Microhabitat Selection.- II. Physiological Aspects of Thermal Relations.- 1. Acclimation to High Temperatures.- 2. Metabolic Homeostasis in Changing Thermal Environments.- 3. Flying Insects: A Special Case.- E. Adaptations to Cold.- I. General Responses to Freezing Temperatures.- II. Comparative Responses to Freezing Temperatures in Desert Invertebrates.- III. Other Metabolic Responses to Cold.- F. Summary Comments.- 7 Energetics.- A. Introduction.- B. Assimilation.- C. Respiration.- D. Production.- Summary Comments: Part 2.- 3 Life-History Patterns.- 8 Short Lives: Multivoltine Species.- A. Introduction.- B. Reproductive Patterns.- C. Patterns of Development and Resource Utilization.- 9 Short Lives: Univoltine Species.- A. Introduction.- B. Reproductive Patterns.- C. Developmental Patterns.- D. Patterns of Resource Utilization.- 10 Long Lives: Herbivores and Detritivores.- A. Introduction.- B. Reproductive Patterns.- C. Developmental Patterns.- I. Slow Growth and Its Consequences.- II. Interactions with Predators.- D. Detritus as a Resource.- 11 Long Lives: Carnivores.- A. Introduction.- B. Reproductive Patterns.- C. Developmental Patterns.- D. Patterns of Resource Utilization.- Summary Comments: Part 3.- 4 Invertebrate Communities: Composition and Dynamics.- Introduction: Use of the Community Concept.- 12 Soil and Litter Community: Nematodes and Microarthropods.- A. Introduction.- B. Distribution.- C. Community Roles.- I. Trophic Relationships.- II. Energetics.- 13 Soil and Litter Community: Social Arthropods.- A. Sociality in Desert Species: General Comments.- B. Ants.- I. Patterns of Distribution.- II. Community Roles.- C. Termites.- I. Patterns of Distribution.- II. Community Roles.- 14 Soil and Litter Community: Temporary Dwellers.- A. Comments on the Fauna.- B. Habitats and Their Temporary Residents.- I. Soil (Including Burrows).- 1. Distribution of Invertebrate Species.- 2. Morphological and Behavioral Adaptations of Soil-Associated Desert Arthropods.- 3. Adaptations of Soil-Associated Carnivorous Arthropods in Deserts.- II. Crevice-Type Habitats.- III. Soil Surface Including Litter.- C. Summary Comments.- 15 Temporary Vegetation Community: Emphasis on Herbivores.- A. Introductory Comments.- B. Consumer Array and Dietary Patterns.- I. Direct Consumers.- II. Pollinators.- III. Carnivores.- C. Characteristics of Plants as Resources for Invertebrate Consumers.- I. Plant Phenology.- II. Aspects of Photosynthesis.- D. Characteristics of Invertebrate Consumers.- I. Seasonal and Diel Feeding Patterns.- II. Patterns of Pollination.- III. Patterns of Behavior and Development.- E. Coevolution of Temporary Desert Vegetation and Its Herbivores.- 16 Perennial Shrub Community.- A. Introductory Comments.- B. Consumer Array and Dietary Patterns.- C. Characteristics of Plants as Resources for Invertebrate Consumers.- I. Plant Phenology.- II. Aspects of Photosynthesis.- D. Characteristics of Invertebrate Consumers.- I. Seasonal and Diel Feeding Patterns.- II. Patterns of Behavior and Development.- E. Coevolution of Perennial Desert Shrubs and Their Herbivores.- 17 The Invertebrate Community of Ephemeral Waters.- A. The Habitat.- B. The Invertebrate Fauna.- C. Reproduction and Development.- I. Reproductive Potential.- II. Embryonic Development and Survival.- III. Hatching.- IV. Posthatching Development and Survival.- D. Adaptation to Abiotic Stress Conditions.- E. Production, Competition, and Seasonal Colonization.- 5 Invertebrates in Desert Ecosystems: Summary Remarks.- A. Introduction.- B. The Temporal Dimension.- C. The Spatial Dimension.- D. Models of Invertebrate Activity in Desert Ecosystems.- E. Future Studies.- I. Adaptation.- II. Life-History Patterns.- III. Community Dynamics.- F. Final Comments.- References.

140 citations


"Foraging at the thermal limit: burr..." refers background in this paper

  • ...Arthropod activity is strongly limited by climatic conditions, especially temperature and humidity (Casey 1981 ; Crawford 1981; Willmer 1982)....

    [...]

01 Jan 1981

110 citations