The Disposition and External Morphology of Trichobothria in Two Arachnids
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A Cluster of Mesenchymal Cells at the Cumulus Produces Dpp Signals Received by Germ Disc Epithelial Cells
Development 130, 1735-1747 1735 © 2003 The Company of Biologists Ltd doi:10.1242/dev.00390 Early patterning of the spider embryo: a cluster of mesenchymal cells at the cumulus produces Dpp signals received by germ disc epithelial cells Yasuko Akiyama-Oda*,†,‡ and Hiroki Oda* JT Biohistory Research Hall, 1-1, Murasaki-cho, Takatsuki, Osaka 569-1125, Japan *Tsukita Cell Axis Project, ERATO, JST †PRESTO, JST ‡Author for correspondence (e-mail: [email protected]) Accepted 16 January 2003 SUMMARY In early embryogenesis of spiders, the cumulus is decapentaplegic (dpp), which encodes a secreted protein characteristically observed as a cellular thickening that that functions as a dorsal morphogen in the Drosophila arises from the center of the germ disc and moves embryo. Furthermore, the spider Dpp signal appeared to centrifugally. This cumulus movement breaks the radial induce graded levels of the phosphorylated Mothers against symmetry of the germ disc morphology, correlating with dpp (Mad) protein in the nuclei of germ disc epithelial the development of the dorsal region of the embryo. cells. Adding data from spider homologs of fork head, Classical experiments on spider embryos have shown that orthodenticle and caudal, we suggest that, in contrast to a cumulus has the capacity to induce a secondary axis when the Drosophila embryo, the progressive mesenchymal- transplanted ectopically. In this study, we have examined epithelial cell interactions involving the Dpp-Mad signaling the house spider, Achaearanea tepidariorum, on the basis of cascade generate dorsoventral polarity in accordance with knowledge from Drosophila to characterize the cumulus at the anteroposterior axis formation in the spider embryo. -
Zootaxa, Araneae, Agelenidae, Agelena
Zootaxa 1021: 45–63 (2005) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA 1021 Copyright © 2005 Magnolia Press ISSN 1175-5334 (online edition) On Agelena labyrinthica (Clerck, 1757) and some allied species, with descriptions of two new species of the genus Agelena from China (Araneae: Agelenidae) ZHI-SHENG ZHANG1,2*, MING-SHENG ZHU1** & DA-XIANG SONG1*** 1. College of Life Sciences, Hebei University, Baoding, Hebei 071002, P. R. China; 2. Baoding Teachers College, Baoding, Hebei 071051, P. R. China; *[email protected], **[email protected] (Corresponding author), ***[email protected] Abstract Seven allied species of the funnel-weaver spider genus Agelena Walckenaer, 1805, including the type species Agelena labyrinthica (Clerck, 1757), known to occur in Asia and Europe, are reviewed on the basis of the similarity of genital structures. Two new species are described: Agelena chayu sp. nov. and Agelena cuspidata sp. nov. The specific name A. silvatica Oliger, 1983 is revalidated. The female is newly described for A. injuria Fox, 1936. Two specific names are newly synony- mized: Agelena daoxianensis Peng, Gong et Kim, 1996 with A. silvatica Oliger, 1983, and A. sub- limbata Wang, 1991 with A. limbata Thorell, 1897. Some names are proposed for these species to represent some particular genital structures: conductor ventral apophysis, conductor median apo- physis, conductor distal apophysis and conductor dorsal apophysis for male palp and spermathecal head, spermathecal stalk, spermathecal base and spermathecal apophysis for female epigynum. Key words: genital structure, revalidation, synonym, review, taxonomy Introduction The funnel-weaver spider genus Agelena was erected by Walckenaer (1805) with the type species Araneus labyrinthicus Clerck, 1757. -
Guseinov, Marusik, Koponen.Pm6
Arthropoda Selecta 14 (2): 153177 © ARTHROPODA SELECTA, 2005 Spiders (Arachnida: Aranei) of Azerbaijan. 5. Faunistic review of the funnel-web spiders (Agelenidae) with the description of new genus and species Ïàóêè (Arachnida: Aranei) Àçåðáàéäæàíà. 5. Ôàóíèñòè÷åñêèé îáçîð ïàóêîâ-âîðîíêîïðÿäîâ (Agelenidae) ñ îïèñàíèåì íîâîãî ðîäà è íîâûõ âèäîâ Elchin F. Guseinov1, Yuri M. Marusik2 & Seppo Koponen3 Ý.Ô. Ãóñåéíîâ1, Þ.Ì. Ìàðóñèê2 è Ñ. Êîïîíåí3 1Institute of Zoology, block 504, passage 1128, Baku 370073 Azerbaijan. Email: [email protected] Èíñòèòóò çîîëîãèè ÀÍ Àçåðáàéäæàíà, êâàðòàë 504, ïðîåçä 1128, Áàêó 370073 Àçåðáàéäæàí. 2Institute for Biological Problems of the North, Portovaya Str. 18, Magadan 685000 Russia. Email: [email protected] Èíñòèòóò áèîëîãè÷åñêèõ ïðîáëåì Ñåâåðà, ÄÂÎ ÐÀÍ, óë. Ïîðòîâàÿ 18, Ìàãàäàí 685000 Ðîññèÿ. 3 Zoological Museum, University of Turku, FI-20014 Turku Finland. Email: [email protected] KEY WORDS: Aranei, Agelenidae, funnel spiders, Caucasus, Azerbaijan, new records, new species, new genus, new combination. ÊËÞ×ÅÂÛÅ ÑËÎÂÀ: Aranei, Agelenidae, ïàóêè-âîðîíêîïðÿäû, Êàâêàç, Àçåðáàéäæàí, íîâûå íàõîäêè, íîâûå âèäû, íîâûé ðîä, íîâàÿ êîìáèíàöèÿ. ABSTRACT. One new genus Azerithonica gen.n. ed for the first time for the fauna of the former Soviet and 14 new species from Azerbaijan are described: Union. In addition to new species three other species Agelescape caucasica sp.n. ($), A. dunini sp.n. (# $), are illustrated: Agelena labyrinthica (Clerck, 1757) A. levyi sp.n. (#), A. talyshica sp.n. ($), Azerithonica (#), Malthonica lyncea (Brignoli, 1978) (# $), Tege- hyrcanica sp.n. (# $, generotype), Malthonica lehtineni naria domestica (Clerck, 1757) (# $). Revised fauna sp.n. (#), M. lenkoranica sp.n. (# $), M. nakhchivan- of Azerbaijan encompass 19 species from 5 genera. -
Dinburgh Encyclopedia;
THE DINBURGH ENCYCLOPEDIA; CONDUCTED DY DAVID BREWSTER, LL.D. \<r.(l * - F. R. S. LOND. AND EDIN. AND M. It. LA. CORRESPONDING MEMBER OF THE ROYAL ACADEMY OF SCIENCES OF PARIS, AND OF THE ROYAL ACADEMY OF SCIENCES OF TRUSSLi; JIEMBER OF THE ROYAL SWEDISH ACADEMY OF SCIENCES; OF THE ROYAL SOCIETY OF SCIENCES OF DENMARK; OF THE ROYAL SOCIETY OF GOTTINGEN, AND OF THE ROYAL ACADEMY OF SCIENCES OF MODENA; HONORARY ASSOCIATE OF THE ROYAL ACADEMY OF SCIENCES OF LYONS ; ASSOCIATE OF THE SOCIETY OF CIVIL ENGINEERS; MEMBER OF THE SOCIETY OF THE AN TIQUARIES OF SCOTLAND; OF THE GEOLOGICAL SOCIETY OF LONDON, AND OF THE ASTRONOMICAL SOCIETY OF LONDON; OF THE AMERICAN ANTlftUARIAN SOCIETY; HONORARY MEMBER OF THE LITERARY AND PHILOSOPHICAL SOCIETY OF NEW YORK, OF THE HISTORICAL SOCIETY OF NEW YORK; OF THE LITERARY AND PHILOSOPHICAL SOClE'i'Y OF li riiECHT; OF THE PimOSOPHIC'.T- SOC1ETY OF CAMBRIDGE; OF THE LITERARY AND ANTIQUARIAN SOCIETY OF PERTH: OF THE NORTHERN INSTITUTION, AND OF THE ROYAL MEDICAL AND PHYSICAL SOCIETIES OF EDINBURGH ; OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA ; OF THE SOCIETY OF THE FRIENDS OF NATURAL HISTORY OF BERLIN; OF THE NATURAL HISTORY SOCIETY OF FRANKFORT; OF THE PHILOSOPHICAL AND LITERARY SOCIETY OF LEEDS, OF THE ROYAL GEOLOGICAL SOCIETY OF CORNWALL, AND OF THE PHILOSOPHICAL SOCIETY OF YORK. WITH THE ASSISTANCE OF GENTLEMEN. EMINENT IN SCIENCE AND LITERATURE. IN EIGHTEEN VOLUMES. VOLUME VII. EDINBURGH: PRINTED FOR WILLIAM BLACKWOOD; AND JOHN WAUGH, EDINBURGH; JOHN MURRAY; BALDWIN & CRADOCK J. M. RICHARDSON, LONDON 5 AND THE OTHER PROPRIETORS. M.DCCC.XXX.- . -
First Record of Spider Tegenaria Ferruginea (Panzer, 1804) from Belarus with Notes on Overwintering
EUROPEAN JOURNAL OF ECOLOGY EJE 2019, 5(1): 11-14, doi:10.2478/eje-2019-0001 First record of spider Tegenaria ferruginea (Panzer, 1804) from Belarus with notes on overwintering 1Adam Mickiewicz Uni- Maryia Tsiareshyna1 versity in Poznań Poznań, Poland Corresponding author, E-mail: rimskaya1997@ ABSTRACT mail.ru First record of the spider Tegenaria ferruginea (Panzer, 1804) from Belarus, along with taxonomic diagnosis and photographs are presented. Contrary to the expectations, males and females were found during overwintering in the silken sac in the fort of Brest, Belarus. KEYWORDS Agelenidae; Araneae; epigyne; fort; hibernation; Tegenaria © 2019 Maryia Tsiareshyna This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivs license INTRODUCTION agrestis (Walckenaer, 1802), Eratigena atrica (C. L. Koch, 1843) Belarus is a lowland country in Central Europe; a large part of and Tegenaria domestica (Clerck, 1757). Usually, they are spi- it is covered by peatlands. Although in recent years, the num- ders of a small or medium size, characterized by long legs end- ber of spider species reported from Belarus has increased, the ing in three claws and tarsus with a row of long trichobotrias. arachnofauna in this region is still not sufficiently studied in The spinnerets are long, mobile and posterior pair consist of comparison to other European countries (Petrusevich et al., two segments. These spiders build horizontal, sheet like webs, 2008; Ivanov, 2013; Hajdamowicz et al., 2015). Most of the re- ending with a funnel, which is the spider’s shelter. Represen- ported species from Belarus are so far cosmopolitan. According tatives of this family can be found in dense vegetation, under to the catalog “araneae–Spiders of Europe”, currently, 474 spe- stones, but also often in apartments, in basements and on at- cies of spiders from Belarus have been identified (Nentwig et tics (Roberts, 1995). -
Venomous Spiders of Turkey (Araneae)
Journal of Applied Biological Sciences 1 (3): 33-36, 2007 Venomous Spiders of Turkey (Araneae) Abdullah BAYRAM1* Nazife YİĞİT1 Tarık DANIŞMAN1 İlkay ÇORAK1 Zafer SANCAK1 Derya ULAŞOĞLU2 1 Department of Biology, Faculty of Science and Arts, University of Kırıkkale, 71450 Kırıkkale, TURKEY 2 Vera Pest Control, Ulus, İstanbul, TURKEY * Corresponding Author Received: 26 May 2006 e-mail: [email protected] Accepted: 25 October 2006 Abstract Over 50.000 species have been described on the world. Among them about 100 species are dangerous for human. Members of Latrodectus and Loxosceles share the habitats of human beings. Chemically, spider venom is heterogeneous, and contains poly peptide, poly amine, nucleic acid, free amino acid, monoamine, neurotoxin, enzyme and inorganic elements. In enzymes, proteases, hyaluronidase, sphingo-myelinase, phospholipase and isomerase form necrosis. Venom is neurotoxic, and it causes paralysis. In Turkey, some species of Latrodectus, Steatoda, Loxosceles, Cheiracanthium, Segestria, Agelena, Tegenaria, Araneus and Argiope are venomous. The specimens that collected from different habitats and localities of Turkey were examined under stereo microscope. They were identified as species level, and the venom organs of some spiders were investigated morphologically with the light and electron microscope. Key words: Spider, Venom, Turkey, Araneae. INTRODUCTION The aim of this article is to explain the venomous spiders, and inform their habitats and distributions in Turkey. About 50.000 species have been described on the world. All of the spiders have venom glands except the members of MATERIAL AND METHODS Uloboridae and Archaeidae. Preys of spiders are insects, other arthropods and invertebrates, and from vertebrates small fishes, The specimens were collected from different habitats frogs, lizards, birds and even mammalians such as mice. -
Spiders and Harvestmen on Tree Trunks Obtained by Three Sampling Methods 67-72 © Arachnologische Gesellschaft E.V
ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Arachnologische Mitteilungen Jahr/Year: 2016 Band/Volume: 51 Autor(en)/Author(s): Machac Ondrej, Tuf Ivan H. Artikel/Article: Spiders and harvestmen on tree trunks obtained by three sampling methods 67-72 © Arachnologische Gesellschaft e.V. Frankfurt/Main; http://arages.de/ Arachnologische Mitteilungen / Arachnology Letters 51: 67-72 Karlsruhe, April 2016 Spiders and harvestmen on tree trunks obtained by three sampling methods Ondřej Machač & Ivan H. Tuf doi: 10.5431/aramit5110 Abstract. We studied spiders and harvestmen on tree trunks using three sampling methods. In 2013, spider and harvestman research was conducted on the trunks of selected species of deciduous trees (linden, oak, maple) in the town of Přerov and a surrounding flood- plain forest near the Bečva River in the Czech Republic. Three methods were used to collect arachnids (pitfall traps with a conservation fluid, sticky traps and cardboard pocket traps). Overall, 1862 spiders and 864 harvestmen were trapped, represented by 56 spider spe- cies belonging to 15 families and seven harvestman species belonging to one family. The most effective method for collecting spider specimens was a modified pitfall trap method, and in autumn (September to October) a cardboard band method. The results suggest a high number of spiders overwintering on the tree bark. The highest species diversity of spiders was found in pitfall traps, evaluated as the most effective method for collecting harvestmen too. Keywords: Araneae, arboreal, bark traps, Czech Republic, modified pitfall traps, Opiliones Trees provide important microhabitats for arachnids includ- This study is focused on the comparison of the species ing specific microclimatic and structural conditions in the spectrum of spiders and harvestmen obtained by three sim- bark cracks and hollows (Wunderlich 1982, Nikolai 1986). -
A Morphological Study on the Venom Apparatus of Spider
TurkJZool 29(2005)351-356 ©TÜB‹TAK AMorphologicalStudyontheVenomApparatusofSpider LarinioidesCornutus(Araneae,Araneidae) Külti¤inÇAVUfiO⁄LU,AbdullahBAYRAM,MeltemMARAfi K›r›kkaleUniversity,FacultyofScienceandArts,DepartmentofBiology,71450Yahflihan,K›r›kkale-TURKEY TalipKIRINDI K›r›kkaleUniversity,FacultyofScienceandArts,DepartmentofPhysics,71450Yahflihan,K›r›kkale-TURKEY KürflatÇAVUfiO⁄LU SüleymanDemirelUniversity,FacultyofScienceandArts,DepartmentofBiology,32260Çünür,Isparta-TURKEY Received:31.08.2004 Abstract: Themorphologicalstructureofthevenomapparatusof Larinioidescornutus wasstudiedusingascanningelectron microscope(SEM).TheVenomglandsaresituatedintheanteriorcephalicpartoftheprosoma,andeachglandconsistsofalong cylindricalpartandanadjoiningduct,whichterminatesatthetipofthecheliceralfang.Eachcheliceraconsistsof2parts: astout basalpartcoveredbyhair,andamovablefang.Thereareparallelgroovesonthedorsalsurfaceofthefang.Theventralsurfa ce hashollowslikesawteeth.Avenomporeissituatedonthesubterminalpartofthefang.Belowthefang,thereisacheliceralgroove betweentheteeth.Eachsideofthegrooveisarmedwithcuticularteeth.Venomglandsaresmallandsimilartoanaurberginei n shape.Eachglandissurroundedbycompletelystriatedmuscularfibers.Thevenomproducedinthevenomglandsisejectedintothe fangthroughtheductbycontractionofthesemuscularfibers. KeyWords: Larinioidescornutus,venomgland,,morphology,chelicerae,scanningelectronmicroscope(SEM) LarinioidesCornutus(Araneae,Araneidae) Örümce¤inin ZehirAyg›t›ÜzerineMorfolojikBirÇal›flma Özet: Buçal›flmada, Larinioidescornutus ’unzehirayg›t›n›nmorfolojikyap›s›taramal›electronmikroskobu(SEM)kullan›larak -
From Africa (Araneae, Agelenidae)
African InvertebratesOn the species 60(1): of 109–132 the genus (2019) Mistaria Lehtinen, 1967 studied by Roewer (1955) from Africa 109 doi: 10.3897/AfrInvertebr.60.34359 RESEARCH ARTICLE http://africaninvertebrates.pensoft.net On the species of the genus Mistaria Lehtinen, 1967 studied by Roewer (1955) from Africa (Araneae, Agelenidae) Grace M. Kioko1,2,3, Peter Jäger4, Esther N. Kioko2, Li-Qiang Ji1,3, Shuqiang Li1,3 1 Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China 2 National Museums of Kenya, Mu- seum Hill, P.O. Box 40658-00100, Nairobi, Kenya 3 University of Chinese Academy of Sciences, Beijing 100049, China 4 Senckenberg Research Institute, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany Corresponding author: Shuqiang Li ([email protected]) Academic editor: John Midgley | Received 7 March 2019 | Accepted 17 May 2019 | Published 19 June 2019 http://zoobank.org/4D3609D5-89D4-4E8C-B787-A1070D903C17 Citation: Kioko GM, Jäger P, Kioko EN, Ji L-Q, Li S (2019) On the species of the genus Mistaria Lehtinen, 1967 studied by Roewer (1955) from Africa (Araneae, Agelenidae). African Invertebrates 60(1): 109–132. https://doi.org/10.3897/ AfrInvertebr.60.34359 Abstract Eleven species of the spider family Agelenidae Koch, 1837 are reviewed based on the type material and transferred from the genus Agelena Walckenaer, 1805 to Mistaria Lehtinen 1967. These species occur in various African countries as indicated and include: M. jaundea (Roewer, 1955), comb. nov. (♂, Came- roon), M. jumbo (Strand, 1913), comb. nov. (♂♀, Central & East Africa), M. kiboschensis (Lessert, 1915), comb. nov. (♂♀, Central & East Africa), M. keniana (Roewer, 1955), comb. -
Zootaxa, Araneae, Agelenidae, Agelena
Zootaxa 1021: 45–63 (2005) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA 1021 Copyright © 2005 Magnolia Press ISSN 1175-5334 (online edition) On Agelena labyrinthica (Clerck, 1757) and some allied species, with descriptions of two new species of the genus Agelena from China (Araneae: Agelenidae) ZHI-SHENG ZHANG1,2*, MING-SHENG ZHU1** & DA-XIANG SONG1*** 1. College of Life Sciences, Hebei University, Baoding, Hebei 071002, P. R. China; 2. Baoding Teachers College, Baoding, Hebei 071051, P. R. China; *[email protected], **[email protected] (Corresponding author), ***[email protected] Abstract Seven allied species of the funnel-weaver spider genus Agelena Walckenaer, 1805, including the type species Agelena labyrinthica (Clerck, 1757), known to occur in Asia and Europe, are reviewed on the basis of the similarity of genital structures. Two new species are described: Agelena chayu sp. nov. and Agelena cuspidata sp. nov. The specific name A. silvatica Oliger, 1983 is revalidated. The female is newly described for A. injuria Fox, 1936. Two specific names are newly synony- mized: Agelena daoxianensis Peng, Gong et Kim, 1996 with A. silvatica Oliger, 1983, and A. sub- limbata Wang, 1991 with A. limbata Thorell, 1897. Some names are proposed for these species to represent some particular genital structures: conductor ventral apophysis, conductor median apo- physis, conductor distal apophysis and conductor dorsal apophysis for male palp and spermathecal head, spermathecal stalk, spermathecal base and spermathecal apophysis for female epigynum. Key words: genital structure, revalidation, synonym, review, taxonomy Introduction The funnel-weaver spider genus Agelena was erected by Walckenaer (1805) with the type species Araneus labyrinthicus Clerck, 1757. -
20 4 273 282 Kovblyuk Agelena for Inet.P65
Arthropoda Selecta 20(4): 273282 © ARTHROPODA SELECTA, 2011 On two closely related funnel-web spider species, Agelena orientalis C.L. Koch, 1837, and A. labyrinthica (Clerck, 1757) (Aranei: Agelenidae) Äâà áëèçêèõ âèäà ïàóêîâ-âîðîíêîïðÿäîâ Agelena orientalis C.L. Koch, 1837 è A. labyrinthica (Clerck, 1757) (Aranei: Agelenidae) Mykola M. Kovblyuk, Zoya A. Kastrygina Í.Ì. Êîâáëþê, Ç.À. Êàñòðûãèíà Zoology Department, V.I. Vernadsky Taurida National University, 4 Yaltinskaya str., Simferopol 95007, Ukraine. E-mail: [email protected]; [email protected] Êàôåäðà çîîëîãèè Òàâðè÷åñêîãî íàöèîíàëüíîãî óíèâåðñèòåòà èì. Â.È.Âåðíàäñêîãî, óë. ßëòèíñêàÿ 4, Ñèìôåðîïîëü 95007, Óêðàèíà. KEY WORDS: spiders, Agelena, redescriptions, spatial distribution, phenology, Crimea. ÊËÞ×ÅÂÛÅ ÑËÎÂÀ: ïàóêè, Agelena, ïåðåîïèñàíèÿ, ëàíäøàôòíîå ðàñïðåäåëåíèå, ôåíîëîãèÿ, Êðûì. ABSTRACT. Redescriptions of two closely related Correct identification of Agelena species in Crimea species Agelena orientalis C.L. Koch, 1837 and A. is problematic for a number of reasons. Little-known labyrinthica (Clerck, 1757) are provided, based on species A. orientalis can be easy misidentified with a specimens from Crimea, continental Ukraine and Abk- well-known species, A. labyrinthica. Although many hazia (West Caucasus). Crimea is supposed to be the illustrations and descriptions were made for both spe- northernmost point of A. orientalis distribution. Com- cies [see Platnick, 2011], only two papers contained parative illustrations, diagnoses, spatial distribution, comparative drawings [Blauwe, 1980; Levy, 1996]. A. seasonal dynamics of activity for both species are pre- orientalis is an ecological vicariant of A. labyrinthica sented. [cf. Guseinov et al., 2005: 155], so only one of these species could possibly be distributed within the small ÐÅÇÞÌÅ. Ïî ýêçåìïëÿðàì èç Êðûìà, ìàòåðè- Crimean peninsula. -
Orientation by Jumping Spiders of the Genus Phidippus (Araneae: Salticidae) During the Pursuit of Prey
Behavioral Ecology Behav. Ecol. Sociobiol. 5,301 322 (1979) and Sociobiology by Springer-Verlag 1979 Orientation by Jumping Spiders of the Genus Phidippus (Araneae: Salticidae) During the Pursuit of Prey David Edwin Hill Section of Neurobiology and Behavior, Langmuir Laboratory, Cornell University, Ithaca, New York 14850, USA Received September 18, 1978 Summary. 1. Jumping spiders of the genus Phidippus tend to occupy waiting positions on plants during the day. From such reconnaissance positions, the spiders often utilize an indirect route of access (detour) to attain a position from which sighted prey (the primary objective of pursuit) can be captured. 2. Selection of an appropriate route of access is based upon movement toward a visually determined secondary objective (part of a plant) which may provide access to the prey position (Fig. 2, Table 1). 3. During pursuit, the spider retains a memory of the relative position of the prey at all times. This memory of prey position is frequently expressed in the form of a reorientation turn to face the expected position of the prey (Fig. 1). Each reorientation can be considered to initiate a new segment of the pursuit. 4. Phidippus employ the immediate direction (or route) of pursuit as a reference direction, for the determination of prey position (Figs. 3 and 4). The spider compensates for its own movement in determining the direction of the prey from a new position (Fig. 5). 5. The spider retains a memory of the prey direction with reference to gravity (Fig. 6); this memory of the inclination of prey direction can take precedence over conflicting information based upon the use of the route as a reference direction (Figs.