Orb weaving spiders have devised both webs and special devices for capturing prey. The prey have also evolved mechanisms for eluding spiders and for living with them. Some of the mechanisms involved are discussed in this paper

Dorris, Peggy Rae

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Journal of the Arkansas Academy of ScienceVolume 40 Article 101986Special Adaptations of Orb Weavers and PreyPeggy Rae DorrisHenderson State UniversityFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Entomology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academyof Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationDorris, Peggy Rae (1986) "Special Adaptations of Orb Weavers and Prey," Journal of the Arkansas Academy of Science: Vol. 40 , Article10.Available at: http://scholarworks.uark.edu/jaas/vol40/iss1/1026Proceedings Arkansas Academy of Science, Vol. XXXX,1986SPECIAL ADAPTATIONS OFORB WEAVERS AND PREYPEGGY RAE DORRISDepartment of BiologyHenderson State UniversityArkadelphia, AR 71923ABSTRACTOrb weaving spiders have devised both webs and special devices for capturing prey. The prey havealso evolved mechanisms for eluding spiders and forliving with them. Some of the mechanisms involvedare discussed in this paper.INTRODUCTIONOrb weavers have devised webs and other devices for capturing prey.Prey have also evolved mechanisms foreluding spiders. Eberhard (1976,1977) discussed physical properties ofsticky spirals and their connec-tions and aggressive chemical mimicry by a bolas spider. Eisner (1964)also commented on the adhesiveness of spider silk. Craig, Akira, andViggo (1985) indicated that oscillation of orb webs had an effect onprey interception. Ploy and counterploy inpredator-prey interactionswas discussed by Eisner and Dean (1976). Some spiders are so smallthat they are unnoticed in other webs as pointed out by Exline and Levi(1962). Web structure and function is cited by Lubin (1973). Somespiders show adaptive advantage by living in colonies (Lubin, 1974).Rypstra (1984) discussed the importance of food and space in limitingweb-spider densities. McMillan (1975) observed flies of the familyMilichiidae cleaning the anus of Araneus and Nephila. Predatorybehavior is discussed by Robinson (1969, 1973). Thornhill (1975) referredto scorpionflies as kleptoparasites because of the way in which theysteal food from spiders webs. Mechanisms involved in predator-preyrelationships have been noticed by various investigators.MATERIALSAND METHODSA 35 mm camera with various lenses was used to photograph websofspiders. Some webs were sprayed with white spray paint witha blackvelvet cloth used as a background, some webs were photographed inthe wild withouta background, others were photographed frombooksor journals where appropriate.Spiders and insects were collected from webs, put in70% ethyl alcoholand brought to the laboratory for identification with a stereoscopicmicroscope.RESULTSOf the approximately 35,000 species of spiders, one half make websfor trapping prey. Rypstra (1984) pointed out that prey availability andhabitat structures were possible limiting factors of web spider density.Itappears that large numbers of prey and suitable habitat structuresalmost always determine spider densities. However; some New Guineaspiders live inlarge colonies that span huge areas withcontiguous webs.These webs are not removed often and they catch few insects. Orb webs,sheet webs, and irregular webs comprise the basic types of webs. Thereare trip lines leading from tubes, bits of bark or webbing situated inwebs to mimic spiders and many other modifications of these three basictypes of webs used for trapping prey. Spiders may also build a retreatin a crack of wood ora rolled leaf, (Figure 1). Orb weavers use viscidsticky silk or hackled wooly threads in the permanent spiral threadswhich adhere to prey. Itwas also shown by Craig, Akiro,and Viggo(1985) that orb webs are not static nets and capture reflects a dynamicinteraction between spider and insect. One component of this interac-tion is web oscillation. The natural oscillations of orb webs greatlyenhances web interception of small and slow flyingprey. Size of meshalso has a distinct bearing upon prey trapped, (Figures 2 and 3). General-ly speaking, spiders run from a nearby retreat and thrust their poisonfangs into prey caught in the web; (Figure 4) however, ifthe prey isa stinging insect the spider will usually immediately attack-wrap bythrowing swaths of silk over itand then rolling the insect into the silkto prevent counter attack (Figure 5).Insome species of orb weavers the spider bites the center out entire-ly and leaves a hole, (Figure 6) which permits the spider to move fromone face of the web to the other. Some spiders control web tension byholding to the rimofthe hole. Ina zigzag fashion a stabilimentum whichis a heavy decorative band of silk may be added above and below thehub. Many orb-weavers place irregular threads — a barrier web — infront ofor behind the main web, perhaps as an alarm system to warnof the approach of larger predators. Some species sit ona branch holdinga single line witha visual glob at its end: they attract male moths witha pheromone that mimics the pheromone of the female moth accord-ing to Eberhard (1977).Figure 1. Bits of webbing used to mimic spiders sitting in web. (Seespider at top of plant.)26Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10Published by Arkansas Academy of Science, 1986Peggy Rae DorrisFigure 4. Spiders run from a retreat and thrust fangs into prey.Figure 5. Insect wrapped.Figures 2 &3. Size of mesh has a distinct bearing upon prey trapped.Proceedings Arkansas Academy off Science, Vol. XXXX,1986 27 27Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10http://scholarworks.uark.edu/jaas/vol40/iss1/10!stf!Ii28Proceedings Arkansas Academy of Science, Vol. XXXX,1986Special Adaptations of Orb Weavers and PreySome orb-weavers make webs during different times of the day ornight to attract different insects and many species tear down their webseach day toprevent an abundance of kleptopar ashes, web robbers, diur-nal predators, human spider collectors, and other prey from locatingthem so easily (Figure 7).The trapdoor spider's trap is an example ofa different approach tocatching prey. Itlives in a silk-linedburrow that has a trapdoor flushwith the ground (Figure 8). Atnight the spider opens the trapdoor slight-ly and preys onpassersby. Wolf spiders, jumping spiders, fishing spiders,and some ground spiders hunt, fish or prey without the use of webs.Once the prey is safely ensheathed itcannot use bites, stings, kick-ing legs, ornoxious defense fluids. Various authorities have reportedadaptations of prey to thwart spiders. Robinson (1976) reported on apyralid moth that rests on silk strands of a Nephila web. The fact thatitlooks like debris protects itfrom birds flyingabove and prevents at-tack from the spider also. Eisner (1964) showed that moths and but-terflies are protected from sticky threads. Scales covering their wingsget stuck to the web, but the moths can easily pullaway from the scalesand elude the owners of their temporary retreat. According to Robin-son (1969) some orb weavers can differentiate moths and butterfliesfrom other insects and employ different attack strategy. Moths are im-mediately bitten and held down until their movements cease.Panorpa species ofscorpionflies which scavenge on dead and dyinginsects, have been observed removing silk from wrapped insects in websby regurgitating a brown fluid which dissolves the webbing; therebypermitting the scavenger to flyaway withthe insect. According to Thor-nhill (1975) 59% of scorpionfly mortality is due to getting caught byorb weavers.Levi(1978) watched small phorid flies sitting around the head of theorb-weaver Araneus bogotensis. As soon as the spider retrieved an in-sect the flies started feeding at one end while the spider fed more slow-ly at the other end. Robinson and Robinson (1978) observeddrosophiloid flies sitting on the head of a golden silk spider waitingfor it to catch food.Spiders must adapt not only to the defense mechanisms ofpotentialFigure 6. Spider bites out center of web and leaves hole to move fromone face of the web to the other.Figure 8. The trapdoor spider's door is flush with the ground and atnight it opens the door slightly and preys on passersby.Figure 7. Spider tearing down its web to prevent kleptoparasitism byspiders and to prevent other prey from locating them so easily.28Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10Published by Arkansas Academy of Science, 1986Proceedings Arkansas Academy off Science, Vol. XXXX,1986 29Peggy Rae Dorrisprey but to web-robbers as mentioned above. The most common klep-toparasites are not insects but spiders. Tiny spiders of the genusArgyrodes (family Theridiidae) have been observed at one time withsOme feeding and removing prey inthe daytime and some at night. Thisbehavior has also been noted in webs of spiny bellied spiders such asVficrothena and Gasteracantha. Most spiders tear down their webs dailyto prevent kleptoparasitism.Symbiotic relationships have been observed by McMillan(1975). Amechilid flyin Australia cleans orb-weavers. Itlicks around the analarea and is allowed to clean up food remains.Spiders obviously have evolved many strategies and counter-strategiesagainst protective devices, kleptoparasites, web robbers and other would-be enemies or prey. Likewise, prey have evolved mechanisms to copewith these adaptations and strategies.DISCUSSIONThe present research has indicated that spiders and their webs showcertain adaptations for trapping prey; whereas, some prey also seemtobe anatomically, physiologically, behaviorally, or ecologically adaptedfor obtaining food from spiders webs or for eluding spiders whiletrying to steal food. Webs are ideal forstudying spider's adaptationsto the food supply and to prey's evasive behavior. Different web con-figurations and the expense of making webs compared to the energyobtained from catching prey are all interesting aspects associated withadaptations of spiders and prey.LITERATURE CITEDCRAIG, C. L., O. AKIRA,and A. VIGGO. 1985. Effect of spiderOrb- Web and insect oscillation onprey interception. J. Theor. Biol.115(2):201-212.EBERHARD, W. G. 1976. Physical properties of sticky spirals andtheir connections: Sliding connections in orb- webs. J. Natur. Hist.,London 10:481-488.EBERHARD, W. G. 1977. Aggressive chemical mimicry by a bolasspider. Science 198:1173.EISNER, T., R. ALSOP, and G. ETTERSHANK. 1964. Adhesivenessof spider silk. Science 146:1058-1061.EXLINE,H., and H. W. LEVI.1962. American spiders of the genusArgyrodes (Araneae, Theridiidae). Bull. Mus. Comp. Zool.127(2):75-204.LEVI, H. W. 1978. Orb weaving spiders and their webs. Amer. Sci.66:734-742.LUBIN,Y. D. 1973. Web structure and function: The non-adhesiveorb-web of Cyrtophora moluccensis (Doleschall) (araneae:Araneidae). Forma et Functio 6:337-358.LUBIN,Y. D. 1974. Adaptive advantages and the evolution of colonyformation in Crytophora moluccensis (Araneae: Araneidae). Zool.J. Linnean Soc. London 53:321-339.McMILLAN, R. P. 1975. Observations of flies of the familyMilichiidae cleaning Araneus and Nephila spiders. West. AustralianNatur. 13(4):96.ROBINSON, M.H. 1969. Predatory behavior of Argiope argentata(Fabricius). Amer. Zool. 9:161-173.ROBINSON, M.H., and B. ROBINSON. 1973. Ecology and behaviorof the Giant Wood Spider Nephila maculata (Fabricius) in NewGuinea. Smithsonian Contrib. Zool. no. 149:1-76.ROBINSON, M. H. 1976. The ecology and behavior of Nephilamaculata: A supplement. Smithsonian Contrib. Zool. vol218:1-21.ROBINSON, M. H. 1978. Associations between flies and spiders.Psyche 84:150-157.RYPSTRA, A. L.1984. The importance of food and space in limitingweb-spider densities: a test using field enclosures. Oecologia59(2/3)312-316.THORNHILL, R. 1975. Scorpionflies as kleptoparasites of web-building spiders. Nature 258:709-11.29Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10http://scholarworks.uark.edu/jaas/vol40/iss1/10

Special Adaptations of Orb Weavers and Prey

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 40 Article 10 1986 Special Adaptations of Orb Weavers and Prey Peggy Rae Dorris Henderson State University Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Entomology Commons Recommended Citation Dorris, Peggy Rae (1986) "Special Adaptations of Orb Weavers and Prey," Journal of the Arkansas Academy of Science: Vol. 40 , Article 10. Available at: https://scholarworks.uark.edu/jaas/vol40/iss1/10 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. 26Proceedings Arkansas Academy of Science, Vol. XXXX,1986SPECIAL ADAPTATIONS OFORB WEAVERS AND PREYPEGGY RAE DORRISDepartment of BiologyHenderson State UniversityArkadelphia, AR 71923ABSTRACTOrb weaving spiders have devised both webs and special devices for capturing prey. The prey havealso evolved mechanisms for eluding spiders and forliving with them. Some of the mechanisms involvedare discussed in this paper.INTRODUCTIONOrb weavers have devised webs and other devices for capturing prey.Prey have also evolved mechanisms foreluding spiders. Eberhard (1976,1977) discussed physical properties ofsticky spirals and their connec-tions and aggressive chemical mimicry by a bolas spider. Eisner (1964)also commented on the adhesiveness of spider silk. Craig, Akira, andViggo (1985) indicated that oscillation of orb webs had an effect onprey interception. Ploy and counterploy inpredator-prey interactionswas discussed by Eisner and Dean (1976). Some spiders are so smallthat they are unnoticed in other webs as pointed out by Exline and Levi(1962). Web structure and function is cited by Lubin (1973). Somespiders show adaptive advantage by living in colonies (Lubin, 1974).Rypstra (1984) discussed the importance of food and space in limitingweb-spider densities. McMillan (1975) observed flies of the familyMilichiidae cleaning the anus of Araneus and Nephila. Predatorybehavior is discussed by Robinson (1969, 1973). Thornhill (1975) referredto scorpionflies as kleptoparasites because of the way in which theysteal food from spiders webs. Mechanisms involved in predator-preyrelationships have been noticed by various investigators.MATERIALSAND METHODSA 35 mm camera with various lenses was used to photograph websofspiders. Some webs were sprayed with white spray paint witha blackvelvet cloth used as a background, some webs were photographed inthe wild withouta background, others were photographed frombooksor journals where appropriate.Spiders and insects were collected from webs, put in70% ethyl alcoholand brought to the laboratory for identification with a stereoscopicmicroscope.RESULTSOf the approximately 35,000 species of spiders, one half make websfor trapping prey. Rypstra (1984) pointed out that prey availability andhabitat structures were possible limiting factors of web spider density.Itappears that large numbers of prey and suitable habitat structuresalmost always determine spider densities. However; some New Guineaspiders live inlarge colonies that span huge areas withcontiguous webs.These webs are not removed often and they catch few insects. Orb webs,sheet webs, and irregular webs comprise the basic types of webs. Thereare trip lines leading from tubes, bits of bark or webbing situated inwebs to mimic spiders and many other modifications of these three basictypes of webs used for trapping prey. Spiders may also build a retreatin a crack of wood ora rolled leaf, (Figure 1). Orb weavers use viscidsticky silk or hackled wooly threads in the permanent spiral threadswhich adhere to prey. Itwas also shown by Craig, Akiro,and Viggo(1985) that orb webs are not static nets and capture reflects a dynamicinteraction between spider and insect. One component of this interac-tion is web oscillation. The natural oscillations of orb webs greatlyenhances web interception of small and slow flyingprey. Size of meshalso has a distinct bearing upon prey trapped, (Figures 2 and 3). General-ly speaking, spiders run from a nearby retreat and thrust their poisonfangs into prey caught in the web; (Figure 4) however, ifthe prey isa stinging insect the spider will usually immediately attack-wrap bythrowing swaths of silk over itand then rolling the insect into the silkto prevent counter attack (Figure 5).Insome species of orb weavers the spider bites the center out entire-ly and leaves a hole, (Figure 6) which permits the spider to move fromone face of the web to the other. Some spiders control web tension byholding to the rimofthe hole. Ina zigzag fashion a stabilimentum whichis a heavy decorative band of silk may be added above and below thehub. Many orb-weavers place irregular threads—a barrier web— infront ofor behind the main web, perhaps as an alarm system to warnof the approach of larger predators. Some species sit ona branch holdinga single line witha visual glob at its end: they attract male moths witha pheromone that mimics the pheromone of the female moth accord-ing to Eberhard (1977).Figure 1. Bits of webbing used to mimic spiders sitting in web. (Seespider at top of plant.)26Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10Published by Arkansas Academy of Science, 1986Peggy Rae DorrisFigure 4. Spiders run from a retreat and thrust fangs into prey.Figure 5. Insect wrapped.Figures 2 &3. Size of mesh has a distinct bearing upon prey trapped.Proceedings Arkansas Academy off Science, Vol. XXXX,1986 27 27Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10https://scholarworks.uark.edu/jaas/vol40/iss1/10!stf!Ii28Proceedings Arkansas Academy of Science, Vol. XXXX,1986Special Adaptations of Orb Weavers and PreySome orb-weavers make webs during different times of the day ornight to attract different insects and many species tear down their webseach day toprevent an abundance of kleptopar ashes, web robbers, diur-nal predators, human spider collectors, and other prey from locatingthem so easily (Figure 7).The trapdoor spider's trap is an example ofa different approach tocatching prey. Itlives in a silk-linedburrow that has a trapdoor flushwith the ground (Figure 8). Atnight the spider opens the trapdoor slight-ly and preys onpassersby. Wolf spiders, jumping spiders, fishing spiders,and some ground spiders hunt, fish or prey without the use of webs.Once the prey is safely ensheathed itcannot use bites, stings, kick-ing legs, ornoxious defense fluids. Various authorities have reportedadaptations of prey to thwart spiders. Robinson (1976) reported on apyralid moth that rests on silk strands of a Nephila web. The fact thatitlooks like debris protects itfrom birds flyingabove and prevents at-tack from the spider also. Eisner (1964) showed that moths and but-terflies are protected from sticky threads. Scales covering their wingsget stuck to the web, but the moths can easily pullaway from the scalesand elude the owners of their temporary retreat. According to Robin-son (1969) some orb weavers can differentiate moths and butterfliesfrom other insects and employ different attack strategy. Moths are im-mediately bitten and held down until their movements cease.Panorpa species ofscorpionflies which scavenge on dead and dyinginsects, have been observed removing silk from wrapped insects in websby regurgitating a brown fluid which dissolves the webbing; therebypermitting the scavenger to flyaway withthe insect. According to Thor-nhill (1975) 59% of scorpionfly mortality is due to getting caught byorb weavers.Levi(1978) watched small phorid flies sitting around the head of theorb-weaver Araneus bogotensis. As soon as the spider retrieved an in-sect the flies started feeding at one end while the spider fed more slow-ly at the other end. Robinson and Robinson (1978) observeddrosophiloid flies sitting on the head of a golden silk spider waitingfor it to catch food.Spiders must adapt not only to the defense mechanisms ofpotentialFigure 6. Spider bites out center of web and leaves hole to move fromone face of the web to the other.Figure 8. The trapdoor spider's door is flush with the ground and atnight it opens the door slightly and preys on passersby.Figure 7. Spider tearing down its web to prevent kleptoparasitism byspiders and to prevent other prey from locating them so easily.28Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10Published by Arkansas Academy of Science, 1986Proceedings Arkansas Academy off Science, Vol. XXXX,1986 29Peggy Rae Dorrisprey but to web-robbers as mentioned above. The most common klep-toparasites are not insects but spiders. Tiny spiders of the genusArgyrodes (family Theridiidae) have been observed at one time withsOme feeding and removing prey inthe daytime and some at night. Thisbehavior has also been noted in webs of spiny bellied spiders such asVficrothena and Gasteracantha. Most spiders tear down their webs dailyto prevent kleptoparasitism.Symbiotic relationships have been observed by McMillan(1975). Amechilid flyin Australia cleans orb-weavers. Itlicks around the analarea and is allowed to clean up food remains.Spiders obviously have evolved many strategies and counter-strategiesagainst protective devices, kleptoparasites, web robbers and other would-be enemies or prey. Likewise, prey have evolved mechanisms to copewith these adaptations and strategies.DISCUSSIONThe present research has indicated that spiders and their webs showcertain adaptations for trapping prey; whereas, some prey also seemtobe anatomically, physiologically, behaviorally, or ecologically adaptedfor obtaining food from spiders webs or for eluding spiders whiletrying to steal food. Webs are ideal forstudying spider's adaptationsto the food supply and to prey's evasive behavior. Different web con-figurations and the expense of making webs compared to the energyobtained from catching prey are all interesting aspects associated withadaptations of spiders and prey.LITERATURE CITEDCRAIG, C. L., O. AKIRA,and A. VIGGO. 1985. Effect of spiderOrb- Web and insect oscillation onprey interception. J. Theor. Biol.115(2):201-212.EBERHARD, W. G. 1976. Physical properties of sticky spirals andtheir connections: Sliding connections in orb- webs. J. Natur. Hist.,London 10:481-488.EBERHARD, W. G. 1977. Aggressive chemical mimicry by a bolasspider. Science 198:1173.EISNER, T., R. ALSOP, and G. ETTERSHANK. 1964. Adhesivenessof spider silk. Science 146:1058-1061.EXLINE,H., and H. W. LEVI.1962. American spiders of the genusArgyrodes (Araneae, Theridiidae). Bull. Mus. Comp. Zool.127(2):75-204.LEVI, H. W. 1978. Orb weaving spiders and their webs. Amer. Sci.66:734-742.LUBIN,Y. D. 1973. Web structure and function: The non-adhesiveorb-web of Cyrtophora moluccensis (Doleschall) (araneae:Araneidae). Forma et Functio 6:337-358.LUBIN,Y. D. 1974. Adaptive advantages and the evolution of colonyformation in Crytophora moluccensis (Araneae: Araneidae). Zool.J. Linnean Soc. London 53:321-339.McMILLAN, R. P. 1975. Observations of flies of the familyMilichiidae cleaning Araneus and Nephila spiders. West. AustralianNatur. 13(4):96.ROBINSON, M.H. 1969. Predatory behavior of Argiope argentata(Fabricius). Amer. Zool. 9:161-173.ROBINSON, M.H., and B. ROBINSON. 1973. Ecology and behaviorof the Giant Wood Spider Nephila maculata (Fabricius) in NewGuinea. Smithsonian Contrib. Zool. no. 149:1-76.ROBINSON, M. H. 1976. The ecology and behavior of Nephilamaculata: A supplement. Smithsonian Contrib. Zool. vol218:1-21.ROBINSON, M. H. 1978. Associations between flies and spiders.Psyche 84:150-157.RYPSTRA, A. L.1984. The importance of food and space in limitingweb-spider densities: a test using field enclosures. Oecologia59(2/3)312-316.THORNHILL, R. 1975. Scorpionflies as kleptoparasites of web-building spiders. Nature 258:709-11.29Journal of the Arkansas Academy of Science, Vol. 40 [1986], Art. 10https://scholarworks.uark.edu/jaas/vol40/iss1/10

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