Articles

Print Email

Neoichnology of tarantulas (Araneae: Theraphosidae): Criteria for recognizing spider burrows in the fossil record

Daniel I. Hembree

Plain Language Abstract

Heavy bodied spiders such as tarantulas (Mygalomorphae) first appear in the fossil record in the Triassic. While many modern mygalomorph spiders live in burrows, fossil burrows attributable to this group are not well-documented. This study describes the morphology of the burrows of three different types of tarantulas and compares them to the burrows of other large, terrestrial animals in order to improve the recognition of large spider burrows in the fossil record and to improve interpretation of ancient soil ecosystems. This project involved the study of the tarantula species Hysterocrates gigas, Pelinobius muticus, and Aphonopelma chalcodes, which inhabit tropical to subtropical forests, scrublands and grasslands, and semi-arid deserts, respectively. Individual tarantulas were placed in sediment-filled terrariums under temperature and moisture conditions according to their environmental preferences. The tarantulas were observed for three to 12 months after which they were removed and the open burrows were cast with plaster, excavated, and described. Each species constructed burrows by excavating sediment using their mouthparts. Burrow openings were circular to elliptical and lined with thin layers of silk. The tarantulas produced burrows with distinct morphologies: 1) H. gigas: vertical shafts with elongate ovoid chambers near the sediment surface and at depth, 2) P. muticus: subvertical sinuous shafts with and without branches, and 3) A. chalcodes: straight to curved, subhorizontal tunnels. Tarantula burrows as a group were also distinct from burrows of trapdoor spiders, scorpions, salamanders, and skinks. Data collected from these types of experimental studies can be used to better understand assemblages of terrestrial fossil burrows in order to better interpret the composition of ancient soil ecosystems.

Resumen en Español

Neoicnología de tarántulas (Araneae: Theraphosidae): Criterios para reconocer excavaciones de arañas en el registro fósil

Las Mygalomorphae, un suborden de arañas robustas que incluye a las tarántulas, aparece por primera vez en el Triásico. Mientras que excavar es común entre migalomorfas actuales, las excavaciones fósiles atribuibles a este grupo no están bien documentadas. El objetivo de este trabajo es describir la morfología de las excavaciones de tarántulas y compararlas con las excavaciones de otros animales terrestres grandes, con el propósito de mejorar la interpretación de icnofósiles continentales y ecosistemas de suelos fósiles. Este proyecto involucró el estudio de los comportamientos y morfologías de excavación de Hysterocrates gigas, Pelinobius muticus, y Aphonopelma chalcodes (Araneae: Theraphosidae), las cuales habitan bosques tropicales a subtropicales, matorrales y pastizales, y desiertos semiáridos, respectivamente. Las tarántulas fueron depositadas individualmente en terrarios llenos de sedimento bajo condiciones de temperatura y humedad controladas según sus preferencias ambientales. Las tarántulas fueron observadas por tres a 12 meses luego de lo cual fueron removidas, y las excavaciones abiertas fueron moldeadas con yeso, retiradas y descriptas. Cada especie construyó excavaciones removiendo el sedimento con sus quelíceros y pedipalpos. Las aberturas de las excavaciones eran circulares a elípticas y recubiertas con capas delgadas de seda. Las tarántulas produjeron excavaciones con morfologías distintivas : 1) H. gigas: galerías verticales con cámaras ovoides elongadas cercanas a la superficie y en profundidad, 2) P. muticus: galerías sinuosas subverticales con y sin ramificaciones, and 3) A. chalcodes: túneles subhorizontales rectos a curvos. Las excavaciones de tarántulas como grupo también fueron distintas a las excavaciones de arañas tramperas, escorpiones, salamandras y escincos. Los datos colectados de estos estudios neoicnológicos pueden ser aplicados a asociaciones de icnofósiles continentales para interpretar mejor la paleoecología de los ecosistemas de suelos fósiles.

Palabras clave: icnofósiles; trazas fósiles; continental; artrópodo; arácnido; paleoecología

Traducción: Diana Elizabeth Fernández

Résumé en Français

Néo-ichnologie des tarentules (Araneae : Theraphosidae) : critères de reconnaissance des terriers d'araignées dans le registre fossile

Les Mygalomorphae, un sous-ordre d'araignées de grande taille incluant les tarentules, apparaissent au Trias. Bien que les terriers soient communs chez les mygalomorphes actuels, les terriers fossiles attribués à ce groupe sont mal documentés. Le but de cette étude est de décrire la morphologie des terriers de tarentules et de les comparer aux terriers d'autres grands animaux terrestres avec le but d'améliorer l'interprétation des ichnofossiles continentaux et des écosystèmes des sols anciens. Ce projet a consisté en l'étude des comportements de construction des terriers et des morphologies de terriers chez Hysterocrates gigas, Pelinobius muticus, et Aphonopelma chalcodes (Araneae : Theraphosidae), qui habitent les forêts tropicales à subtropicales, les prairies et la brousse, et les déserts semi-arides, respectivement. Les tarentules individuelles ont été placées dans des terrariums remplis de sédiments sous des conditions de température et d'humidité contrôlées correspondant à leurs préférences environnementales. Les tarentules ont été observées de trois à 12 mois puis elles ont été retirées, et les terriers ouverts ont été moulés avec du plâtre, extraits, et décrits. Toutes les espèces ont construit des terriers en creusant le sédiment avec leurs chélicères et pédipalpes. Les ouvertures des terriers étaient circulaires à elliptiques et bordées de fines couches de soie. Les différentes tarentules ont produit des terriers avec des morphologies distinctes : 1) chez H. gigas : des conduits verticaux avec des chambres ovoïdes allongées proches de la surface du sédiment et en profondeur ; 2) chez P. muticus : des conduits subverticaux sinueux avec ou sans branches ; et 3) A. chacodes : des tunnels subhorizontaux, droits à incurvés. Les terriers de l'ensemble des tarentules étaient aussi distincts de ceux d'autres araignées mygalomorphes, de scorpions, de salamandres, et de lézards scincidés. Les données collectées dans ces études néo-ichnologiques peuvent être appliquées aux assemblages d'ichnofossiles continentaux pour mieux interpréter la paléoécologie des écosystèmes des sols anciens.

Mots-clés : ichnofossiles ; traces fossiles ; continental ; arthropode ; arachnide ; paléoécologie

Translator: Antoine Souron

Deutsche Zusammenfassung

Die Neoichnologie der Taranteln (Araneae: Theraphosidae): Kriterien für das Erkennen von Spinnenbauten im Fossilnachweis

Die Mygalomorphae, eine Unterordnung kräftiger Spinnen wie Taranteln, tauchen zuerst in der Trias auf. Während heutige Mygalomorphe häufig graben, sind fossile Bauten, die dieser Gruppe zugeschrieben werden, nicht ausreichend dokumentiert. Diese Untersuchung hat das Ziel die Morphologie der Tarantel-Bauten zu beschreiben und sie mit anderen Bauten großer landlebender Tiere zu vergleichen, in der Absicht die Bestimmung kontinentaler Ichnofossilien und früherer Erd-Ökosysteme zu verbessern. Dieses Projekt untersuchte das Grabverhalten und die Bauten-Morphologie von Hysterocrates gigas, Pelinobius muticus und Aphonopelma chalcodes (Araneae: Theraphosidae), die tropische bis subtropische Regenwälder, Buschland und Grasslandschaften sowie Halbwüsten bewohnen. Einzelne Taranteln wurden bei kontrollierten Temperatur-und Feuchtigkeitskonditionen entsprechend ihrer Vorlieben in sedimentgefüllte Terrarien gesetzt. Nach drei bis 12 Monaten Beobachtung wurden sie herausgenommen und die offenen Bauten wurden in Gips abgegossen, ausgegraben und beschrieben. Die Tiere generierten die Bauten durch einen Sediment-Aushub mit den Cheliceren und Pedipalpen. Die Ausgänge waren rund bis elliptisch und mit einer dünnen Lage von Spinnenseide besetzt. Die Taranteln stellten Bauten her, die unterschiedliche Morphologien aufwiesen: 1) H. gigas: vertikale Schäfte mit länglichen Eikammern nahe der Sedimentoberfläche und in der Tiefe, 2) P. muticus: subvertikale gewundene Schäfte verzweigt und unverzweigt und 3) A. chalcodes: gerade und gekrümmt, subhorizontale Tunnel. Tarantel-Bauten als Gruppe unterscheiden sich von den Bauten der Falltürspinnen, Skorpione, Salamander und Skinke. Die Daten aus diesen neoichnologischen Untersuchungen können auch auf kontinentale ichnofossil Assemblagen angewendet werden um die Paläoökologie früherer Erd-Ökosysteme besser interpretieren zu können.

Schlüsselwörter: Ichnofossilen ; Spurenfossilien; kontinental; Arthropode; Arachnide; Paläoökolog

Translator: Eva Gebauer

Arabic

in progress

Translator: Ashraf M.T. Elewa

 

 

FIGURE 1. 1, Phylogeny of spiders; tarantulas belong to the Mygalomorphae, a basal group of the Opisthothelae. 2, Geographic range of tarantulas. The shaded areas of the map represent known areas containing extant species of tarantulas. 3, Spider morphology.

 figure1

FIGURE 2. Tarantula specimens. 1, Hysterocrates gigas. 2, Pelinobius muticus. 3, Aphonopelma chalcodes.

figure2

FIGURE 3. Examples of sediment-filled terraria. 1, Surface of terrarium surface of for Hysterocrates gigas. 2, Surface of terrarium substrate for Aphonopelma chalcodes. 3, Side view of a 246 L terrarium housing H. gigas.

figure3

FIGURE 4. Quantitative burrow property diagram. 1, Burrows were described by their slope (S), maximum depth (D), tunnel, shaft, and chamber width (w), height (h), and circumference (c), total length (L), and branching angle (BA). 2, Complexity is the sum of the number of segments (s), chambers (h), and surface openings (e) within a single burrow system. 3, Tortuosity is the average sinuosity of the segments within a burrow system. The tortuosity of a single segment is found by dividing the total length (u) by the straight line distance (v). Modified from Hils and Hembree (2015).

 figure4

FIGURE 5. Comparative trace-making animals and casts of their typical burrow morphologies. 1-2, Gorgyrella sp. (trapdoor spider). 3-4, Pandinus imperator (scorpion). 5-6, Ambystoma tigrinum (salamander). 7-8, Mabuya multifasciata (skink).

figure5

FIGURE 6. 1, Specimen of Hysterocrates gigas initiating burrow construction. 2, Continued excavation of H. gigas burrow; sediment from burrow is deposited on the surface behind the burrow opening. 3, Specimen of Pelinobius muticus transporting excavated sediment with its pedipalps up the burrow shaft. 4, Specimen of P. muticus packing excavating sediment into the base of the sediment mound at the top of the burrow shaft. 5, Specimen of H. gigas in its burrow chamber. 6, Specimen of P. muticus in burrow shaft below the burrow opening.

figure6

FIGURE 7. 1, Low mound of excavated sediment produced by Pelinobius muticus ; circular opening is present in the center. 2, Large mound of excavated sediment produced by Hysterocrates gigas with a circular opening in the center of the mound. 3, Extensive spoil pile of excavated sediment extending from the opening of a H. gigas burrow. 4, Side view of an Aphonopelma chalcodes terrarium showing extensive, irregular surface topography produced by burrow excavation as well as the exposed cross section of a helical burrow (at arrow).

 figure7

FIGURE 8. Hysterocrates gigas burrow casts. 1, Side view of vertical burrow with expanded terminal chamber (HG4). 2, Side view of vertical burrow with expanded terminal chamber and a short lower shaft (HG2). 3, Side view of a vertical burrow with and expanded upper chamber and an elongate lower shaft. 4, Side view of a sinuous vertical burrow with an upper and terminal expanded chambers (HG8). 5, Side view of a vertical to horizontal burrow with upper and lower expanded chambers (HG9). 6, Top view of a vertical to horizontal burrow with upper and lower expanded chambers (HG7).

 figure8

FIGURE 9. Pelinobius muticus burrow casts. 1-3, Side views of vertical, sinuous burrows with a laterally expanded terminal chamber (PM6, PM1, PM3, respectively). 4-5, Oblique and side views of a large diameter, vertical sinuous burrow ending with a horizontal tunnel (PM5). 6-7, Side and top views of a vertical burrow terminating in a horizontal tunnel (PM4). The burrow ends with two bifurcating tunnels. 8, Vertical, branching burrow (PM2). 9-10, Oblique and side view of a vertical, sinuous burrow with two branching tunnels (PM7).

 figure9

FIGURE 10. Aphonopelma chalcodes burrow casts. 1, Side view of a subvertical tunnel with a series of parallel ridges along the tunnel wall (at arrow) (AC3). 2, Side view of a subvertical tunnel with a vertical entrance shaft and a laterally expanded terminal chamber (AC7). 3, Top view of a subvertical tunnel (AC1). 4-5, Side and top views of a subvertical tunnel with a changing slope along its length (AC8). 6-7, Oblique and side views of a helical burrow with a series of parallel ridges along the tunnel wall (at arrow) and a laterally expanded terminal chamber (AC6).

figure10

FIGURE 11. Cluster analysis of burrows produced by Hysterocrates gigas (HG, blue, n = 10), Pelinobius muticus (PM, green, n = 8), and Aphonopelma chalcodes (AC, red, n = 9). Burrows sort into four moderately to highly similar (BC > 0.7) clusters by trace maker and architecture (A-D). Cluster A consists entirely of burrows of A. chalcodes ; Cluster B consists of five burrows of H. gigas (83%) and a single burrow of A. chalcodes (17%); Cluster C consists of eight burrows of P. muticus (73%) and three burrows of H. gigas (27%); Cluster D consists of two burrows each of H. gigas (50%) and P. muticus (50%). Values located at the labeled nodes of the dendrogram are the mean Bray-Curtis similarity score of all burrows emanating from that node cluster.

 figure11

FIGURE 12. All animal burrow cluster diagram. Cluster analysis of the burrows produced by Hysterocrates gigas (HG, blue, n = 10), Pelinobius muticus (PM, green, n = 8), and Aphonopelma chalcodes (AC, red, n = 9), the scorpion Pandinus imperator (PI, light blue, n = 9), trapdoor spider Gorgyrella inermis (GI, yellow, n = 7) (yellow), the salamander Ambystoma tigrinum (AT, black, n = 9) (red), and the skink Mabuya multifasciata (MM, purple, n = 8) (green). The burrows sort into 11 highly similar (BC > 0.80) clusters (A-K), each populated primarily by the burrows of a single trace maker: A = 100% P. imperator (n = 9); B = 100% A. chalcodes (n = 4); C = 100% M. multifasciata (n = 6); D = 100% A. tigrinum (n = 4); E = 100% M. multifasciata (n = 2); F = 100% A. tigrinum (n = 5); G = 80% H. gigas (n = 4); H = 88% G. inermis (n = 7); I = 50% H. gigas/A. chalcodes (n = 2 each); J = 100% H. gigas (n = 2); K = 89% P. muticus (n = 8).

figure12

 

 

APPENDIX 1.

Video (click on image) of Aphonopelma chalcodes burrowing through excavation using its pedipalps.

Appendix1 

APPENDIX 2.

Video (click on image) of Pelinobius muticus burrowing through intrusion.

Appendix2 

APPENDIX 3.

Mann-Whitney (MS) and Kolmogorov-Smirnov (KS) test results (p values) from the comparison of the properties of all burrows produced by Hysterocrates gigas, Pelinobius muticus, and Aphonopelma chalcodes. Yellow highlighted p values are considered significant ( p < 0.05). The mean, median, standard deviation, and range of each significantly different property is provided for each species. Highlighted values (blue and green) indicate the greater of the two.

  MW KS   Hysterocrates gigas   Aphonopelma chalcodes
        Mean Median Std Dev Range   Mean Median Std Dev Range
Surface openings 1.000 1.000   1.0 1.0 0.0 1   1.0 1.0 0.0 1
Maximum depth 0.045 0.162   25.1 19.8 15.1 5.9 - 53.0   12.0 9.8 6.0 3.1 - 21.2
Total length 0.178 0.445   36.5 25.5 25.6 6.3 - 84.0   24.3 17.9 16.6 6.1 - 58.8
Maximum width 0.236 0.489   8.6 8.6 2.1 3.8 - 11.6   7.8 7.9 2.2 3.7 - 11.6
Minimum width 0.072 0.144   3.7 3.3 1.7 1.2 - 6.8   5.2 5.0 1.8 2.9 - 8.3
Mean width 0.191 0.162   5.9 5.9 1.3 3.5 - 8.4   6.6 6.6 1.4 3.4 - 7.9
Maximum height 0.347 0.375   7.1 7.4 1.4 4.2 - 8,7   6.3 6.7 1.6 2.4 - 8.2
Minimum height 0.540 0.489   3.2 3.1 1.1 1.4 - 5.3   3.2 2.5 2.1 1.2 - 8.2
Mean height 0.902 0.995   5.1 4.9 1.0 3.3 - 6.6   4.9 5.1 1.5 1.9 - 7.0
Average W/H ratio 0.835 0.489   1.2 1.1 0.2 1.0 - 1.7   1.2 1.2 0.4 0.5 - 1.8
Maximum circumference 0.022 0.012   25.0 24.8 4.7 13.0 - 31.0   19.3 22.3 7.6 2.7 - 25.4
Minimum circumference 0.307 0.759   12.7 11.8 5.2 4.0 - 21.0   10.2 9.9 4.6 1.8 - 17.6
Mean circumference 0.487 0.375   18.5 18.6 3.3 12.2 - 23.2   16.0 18.7 6.2 2.2 - 21.7
Maximum slope 0.002 0.003   89.0 90.0 3.2 80 - 90   57.2 55.0 24.7 25 - 90
Minimum slope 0.215 0.341   42.5 40.0 36.2 0 - 90   22.6 21.0 18.6 0 - 60
Mean slope 0.002 0.003   72.3 80.0 16.9 46 - 90   37.3 28.0 17.1 25 - 77
Complexity 0.006 0.038   3.8 4.0 1.1 2 - 4   2.4 2.0 0.5 2 - 3
Tortuosity 0.120 0.051   1.24 1.21 0.19 1.00 - 1.56   1.28 1.04 0.53 0.98 - 2.50
  MW

 

KS

 

  Hysterocrates gigas   Pelinobius muticus
    Mean Median Std Dev Range   Mean Median Std Dev Range
Surface openings 1.000 1.000   1.0 1.0 0.0 1   1.0 1.0 0.0 1
Maximum depth 0.068 0.047   25.1 19.8 15.1 5.9 - 53.0   36.7 36.0 6.9 27.0 - 48.5
Total length 0.056 0.012   36.5 25.5 25.6 6.3 - 84.0   56.9 56.5 12.2 42.0 - 73.0
Maximum width 0.005 0.001   8.6 8.6 2.1 3.8 - 11.6   4.8 4.7 0.8 4.1 - 6.5
Minimum width 0.050 0.149   3.7 3.3 1.7 1.2 - 6.8   2.4 2.4 0.4 1.8 - 3.2
Mean width 0.002 0.004   5.9 5.9 1.3 3.5 - 8.4   3.4 3.2 0.9 2.6 - 5.6
Maximum height 0.033 0.025   7.1 7.4 1.4 4.2 - 8,7   4.9 4.5 1.8 2.7 - 8.8
Minimum height 0.036 0.064   3.2 3.1 1.1 1.4 - 5.3   2.2 2.2 0.5 1.6 - 2.9
Mean height 0.005 0.004   5.1 4.9 1.0 3.3 - 6.6   3.4 2.9 1.0 2.2 - 5.4
Average W/H ratio 0.259 0.738   1.2 1.1 0.2 1.0 - 1.7   1.0 1.1 0.2 0.7 - 1.2
Maximum circumference 0.003 0.001   25.0 24.8 4.7 13.0 - 31.0   15.2 14.1 2.7 12.5 - 20.5
Minimum circumference 0.021 0.047   12.7 11.8 5.2 4.0 - 21.0   8.0 7.3 1.6 6.5 - 10.5
Mean circumference 0.001 0.001   18.5 18.6 3.3 12.2 - 23.2   11.0 10.5 2.4 8.3 - 16.5
Maximum slope 0.935 0.985   89.0 90.0 3.2 80 - 90   88.8 90.0 3.5 80 - 90
Minimum slope 0.032 0.012   42.5 40.0 36.2 0 - 90   5.0 0.0 7.6 0 - 20
Mean slope 0.117 0.149   72.3 80.0 16.9 46 - 90   59.2 57.5 10.3 48 - 80
Complexity 0.487 0.827   3.8 4.0 1.1 2 - 4   4.4 4.0 1.4 3 - 6
Tortuosity 0.168 0.305   1.24 1.21 0.19 1.00 - 1.56   1.44 1.46 0.33 1.07 - 2.06
  MW

 

KS

 

  Aphonopelma chalcodes   Pelinobius muticus
    Mean Median Std Dev Range   Mean Median Std Dev Range
Surface openings 1.000 1.000   1.0 1.0 0.0 1   1.0 1.0 0.0 1
Maximum depth 0.001 0.001   12.0 9.8 6.0 3.1 - 21.2   36.7 36.0 6.9 27.0 - 48.5
Total length 0.002 0.001   24.3 17.9 16.6 6.1 - 58.8   56.9 56.5 12.2 42.0 - 73.0
Maximum width 0.011 0.005   7.8 7.9 2.2 3.7 - 11.6   4.8 4.7 0.8 4.1 - 6.5
Minimum width 0.001 0.001   5.2 5.0 1.8 2.9 - 8.3   2.4 2.4 0.4 1.8 - 3.2
Mean width 0.001 0.001   6.6 6.6 1.4 3.4 - 7.9   3.4 3.2 0.9 2.6 - 5.6
Maximum height 0.083 0.034   6.3 6.7 1.6 2.4 - 8.2   4.9 4.5 1.8 2.7 - 8.8
Minimum height 0.335 0.638   3.2 2.5 2.1 1.2 - 8.2   2.2 2.2 0.5 1.6 - 2.9
Mean height 0.048 0.029   4.9 5.1 1.5 1.9 - 7.0   3.4 2.9 1.0 2.2 - 5.4
Average W/H ratio 0.331 0.279   1.2 1.2 0.4 0.5 - 1.8   1.0 1.1 0.2 0.7 - 1.2
Maximum circumference 0.075 0.024   19.3 22.3 7.6 2.7 - 25.4   15.2 14.1 2.7 12.5 - 20.5
Minimum circumference 0.135 0.279   10.2 9.9 4.6 1.8 - 17.6   8.0 7.3 1.6 6.5 - 10.5
Mean circumference 0.043 0.005   16.0 18.7 6.2 2.2 - 21.7   11.0 10.5 2.4 8.3 - 16.5
Maximum slope 0.006 0.005   57.2 55.0 24.7 25 - 90   88.8 90.0 3.5 80 - 90
Minimum slope 0.025 0.029   22.6 21.0 18.6 0 - 60   5.0 0.0 7.6 0 - 20
Mean slope 0.009 0.005   37.3 28.0 17.1 25 - 77   59.2 57.5 10.3 48 - 80
Complexity 0.003 0.041   2.4 2.0 0.5 2 - 3   4.4 4.0 1.4 3 - 6
Tortuosity 0.048 0.005   1.28 1.04 0.53 0.98 - 2.50   1.44 1.46 0.33 1.07 - 2.06

APPENDIX 4.

Quantitative measurements of the burrows of comparative animals. All measurements in cm or degrees (slope only); W/H ratio, complexity, and tortuosity are unitless. GI# = Gorgyrella inermis burrow cast identification number; PI# = Pandinus imperator burrow cast identification number; MM# = Mabuya multifasciata burrow cast identification number; AT# = Ambystoma tigrinum burrow cast identification number.

Gorgyrella inermis
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
GI1 1 7.2 7.8 2.1 1.6 1.9 1.9 1.5 1.7 1.1 6.3 5.7 6 85 85 85 2 1.1
GI2 1 7.2 7.9 2.4 1.8 2.1 2.4 1.7 2.1 1 7.6 5.8 7 85 85 85 2 1.1
GI3 1 9.8 10 2.5 1.8 2.2 2.5 1.7 2.1 1 7.8 5.1 6.7 85 85 85 2 1
GI4 1 13.4 13.6 3.2 1.9 2.9 2.9 2.2 2.7 1.1 9.8 6.1 9 85 85 85 2 1
GI5 1 14.2 14.6 2.3 1.8 2.1 1.7 2.4 2.1 1 7.5 5.7 7.1 90 85 87.5 2 1.1
GI6 1 9.4 9.6 3 2.6 2.9 2.8 2.2 2.5 1.2 9.3 7.4 8.6 88 88 88 2 1
GI7 1 16.3 18.4 2.4 1.9 2.1 2.7 1.7 2.1 1 7.9 5.4 6.6 90 78 84 3 1.4
Pandinus imperator
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
PI1 1 6.5 28 7.6 6 6.7 4.4 2.9 3.7 1.8 23.5 17.5 19.3 20 15 17 3 1
PI2 1 5 18 6.3 3.6 5.6 3.6 2.2 2.8 2 18 12 15.1 20 0 13 3 1.1
PI3 1 13 34 11.6 3.9 8.2 4.2 1.9 2.9 2.8 28 10 19.7 50 0 19.3 3 1.1
PI4 1 6 29 7.1 3.8 6.3 3.8 1.7 2.9 2.2 19.5 12 17 20 0 6.7 3 1
PI5 1 7 19.5 6.3 4.8 5.8 2.7 1.8 2.5 2.3 16 13 15.2 20 0 13 2 1
PI6 1 12.5 34 12 7.4 9.6 7.1 3 3.9 2.5 28.5 20.5 24.8 30 0 14 3 1.7
PI7 1 16 34 11.3 5.5 8.7 5.4 3.9 4.5 1.9 27.1 12.2 21.5 30 0 24 3 1.1
PI8 1 14 29 6.4 4.3 5.5 3.4 2.1 2.7 2 16 11 14.1 50 0 21 3 1.1
PI9 1 15 32 8.3 4.2 6.5 5.9 2 4.5 1.4 22.5 12.5 19 30 0 18 3 1.5
Mabuya multifasciata
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
MM1 1 2.3 6.5 2.2 1.9 2 2 1.3 1.6 1.3 7.4 6.8 7.2 51 4 28 2 1.0
MM2 1 5.4 28.7 5.3 2.2 4 3 1.9 2.5 1.6 13.9 7 11.9 32 6 19 2 1.2
MM3 1 5.3 19.6 5.1 1.9 3.3 2.6 1.5 2.1 1.6 12.5 6.5 9.3 42 5 24 3 1.1
MM4 1 2.8 11 3.5 2.4 2.8 2.7 1.6 2 1.4 9.7 7.2 8.4 55 28 42 2 1.2
MM5 1 4.8 11 2.5 2.1 2.3 5.6 2.4 3.6 0.7 14.2 8.1 10.8 30 7 19 2 1.2
MM6 1 5 14.5 2.6 1.9 2.3 2.4 1.4 1.8 1.3 8.2 6.1 6.9 45 10 28 2 1.2
MM7 1 3.8 10.8 4.5 2.2 3.1 2.9 1.4 2.4 1.3 11.8 5.5 8.5 48 3 26 2 1.0
MM8 1 9.4 11.6 4.3 2 2.8 3.4 1.5 2.2 1.2 14.2 6.4 9.6 62 35 49 2 1.2
Ambystoma tigrinum
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
AT1 1 5.8 9.8 3.3 1.2 2.1 2.2 1.1 1.5 1.4 13 4.5 9.8 35 35 35 2 1.5
AT2 1 9.3 19.5 5 1.6 3.5 3.1 1.6 2.4 1.5 11.3 6.1 9.3 67 67 67 2 1.3
AT3 1 4 11.3 4.1 1.9 3.2 2.8 1.6 2.1 1.5 11.1 6.1 8.3 31 31 31 2 1.3
AT4 1 7.5 9 2.1 0.9 1.7 1.7 1.1 1.5 1.1 7.2 4.3 6 64 64 64 2 1.2
AT5 1 9.8 13 4.5 2.9 3.8 3.4 2.6 2.8 1.4 11.6 9.3 10.5 53 53 53 2 1.1
AT6 1 12.4 15.5 3.5 2.4 2.9 2.5 1.3 1.9 1.5 9 6.4 7.6 65 65 65 2 1
AT7 1 8.7 12.5 3.6 2.3 3 3.2 1.5 2.2 1.4 10.6 6.9 8.2 62 62 62 2 1.3
AT8 1 5.2 10 3 2.1 2.7 2 1.5 1.8 1.5 8.4 6.2 7.3 40 40 40 2 1.6
AT9 1 4.2 11.3 2.5 2 2.2 2.6 1.6 2 1.1 8.6 5.8 7.5 40 40 40 2 1.3
 

hembreeDaniel I. Hembree. Department of Geological Sciences, Ohio University, 316 Clippinger Laboratories, Athens, Ohio 45701, USA. This email address is being protected from spambots. You need JavaScript enabled to view it.

Daniel Hembree is an Associate Professor in the Department of Geological Sciences at Ohio University. His research interests primarily lie with animal-substrate interactions in ancient and modern continental environments. These interactions are preserved in the fossil record as trace fossils. Trace fossils provide an in situ record of ancient biodiversity, ecology, and environment. The study of trace fossils, therefore, provides vital information for accurate paleoenvironmental reconstructions. This involves not only the study of paleosols and continental trace fossils throughout geologic time, but also the experimental study of burrowing behaviors of extant terrestrial annelids, arthropods, amphibians, and reptiles. Current research projects involve the study of the influence of climate changes on ancient soils and soil ecosystems including those of the Pennsylvanian and Permian of southeast Ohio, Permian of eastern Kansas, and the Eocene to Miocene of Colorado and Wyoming. 

 

TABLE 1. Tarantula species studied in these experiments, numbers of individuals involved (F/M = females/males), range of lengths of the specimens, the environments and geographic locations that the tarantulas inhabit.

Species # Individuals
(F/M)
Length
(cm)
Environment Location
Hysterocrates gigas 5/3 6 Subtropical to tropical forests West Africa
Pelinobius muticus 6/2 2 Scrublands and grasslands East Africa
Aphonopelma chalcodes 5/3 5 Semi-arid desert Western North America

 

TABLE 2. Experimental parameters used for each tarantula species including terrarium size (in liters), sediment content and depth (in cm), air temperature, and sediment moisture. Sediment components include organic matter (OM), clay (CL), and sand (SA).

Species Terrarium Size
(L)
Sediment Sediment Depth
(cm)
Temperature
(°C)
Moisture
(%)
Hysterocrates gigas 114, 212, 246 OM, CL 35, 50, 55 25-32 60
Pelinobius muticus 114, 212, 246 OM, CL 35, 50, 55 25-30 40
Aphonopelma chalcodes 114, 212, 246 CL, SA 35, 50, 55 25-32 20

 

TABLE 3. Quantitative measurements of tarantula burrows. All measurements in cm or degrees (slope only); W/H ratio, complexity, and tortuosity are unitless. HG# = Hysterocrates gigas burrow cast identification number; PM# = Pelinobius muticus burrow cast identification number; AC# = Aphonopelma chalcodes burrow cast identification number.

Hysterocrates gigas
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
HG1 1 12.0 24.0 9.6 6.8 8.4 5.9 3.3 4.9 1.7 24.5 20.5 23.2 90 25 49 3 1.26
HG2 1 18.0 18.0 8.1 2.3 5.1 6.2 2.8 4.9 1.0 24.5 9.5 16.5 90 90 90 4 1.09
HG3 1 5.9 6.3 3.8 3.3 3.5 4.2 2.9 3.3 1.1 13.0 11.5 12.2 90 90 90 2 1.00
HG4 1 14.5 17.0 8.1 3.2 6.0 7.8 3.8 6.0 1.0 24.5 12.0 19.5 90 70 80 4 1.06
HG5 1 31.0 36.0 9.7 2.8 4.9 7.0 2.8 4.3 1.1 28.0 10.5 17.4 90 40 83 3 1.16
HG6 1 19.5 26.0 8.9 2.5 6.0 6.1 2.0 4.2 1.4 24.5 8.5 17.7 90 0 60 4 1.16
HG7 1 31.0 70.0 10.2 1.2 5.3 8.7 1.4 4.7 1.1 28.0 4.0 15.8 90 0 46 5 1.56
HG8 1 46.0 59.0 8.3 5.8 7.0 7.8 5.3 6.3 1.1 25.0 21.0 22.0 80 40 60 4 1.28
HG9 1 53.0 84.0 11.6 4.1 5.8 8.7 3.4 5.5 1.1 31.0 14.0 21.0 90 0 80 6 1.53
HG10 1 20.0 25.0 7.7 4.9 6.9 8.1 3.9 6.6 1.0 27.0 15.0 19.5 90 70 85 3 1.25
Pelinobius muticus
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min
Circ
Mean Circ Max
Slope
Min Slope Mean Slope Complexity Tortuosity
PM1 1 30.0 42.0 4.1 2.9 3.5 4.4 2.9 3.7 0.9 13.5 10.0 11.8 90 20 60 3 1.40
PM2 1 27.0 45.0 4.2 1.8 2.6 2.7 1.6 2.2 1.2 12.5 7.0 8.3 90 10 54 6 2.06
PM3 1 48.5 53.0 4.7 2.2 3.0 8.8 2.3 4.1 0.7 14.0 6.5 9.5 90 0 67 3 1.10
PM4 1 34.0 64.0 5.1 2.2 3.3 4.5 2.0 2.9 1.1 16.0 7.5 10.5 90 0 48 6 1.52
PM5 1 41.0 72.0 6.5 3.2 5.6 6.1 2.8 5.4 1.0 20.5 10.5 16.5 90 0 55 4 1.57
PM6 1 34.0 46.0 4.1 2.5 2.9 4.0 2.5 2.8 1.0 13.0 9.0 10.5 80 0 60 3 1.07
PM7 1 38.0 73.0 4.7 2.3 3.2 4.0 1.8 2.9 1.1 14.2 6.5 10.1 90 10 50 4 1.22
PM8 1 41.0 60.0 4.8 2.4 3.1 4.7 1.9 2.9 1.1 17.5 7.0 11.0 90 0 80 6 1.62
Aphonopelma chalcodes
ID Openings Depth Length Max Width Min Width Mean Width Max Height Min Height Mean Height W/H Ratio Max Circ Min Circ Mean Circ Max Slope Min Slope Mean Slope Complexity Tortuosity
AC1 1 9.5 17.9 7.6 3.6 6.6 6.7 2.5 5.1 0.8 22.2 11.1 19.1 55 0 28 2 1.04
AC2 1 3.1 6.1 3.7 2.9 3.4 2.4 1.2 1.9 0.5 10.9 7.1 9.5 25 25 25 2 0.98
AC3 1 7.5 13.5 6.0 8.3 7.9 6.1 8.2 7.0 1.0 19.2 7.4 16.6 35 19 25 3 1.00
AC4 1 9.8 21.3 8.3 5.0 6.5 8.2 4.6 6.5 1.0 25.4 17.6 21.7 62 21 35 3 1.84
AC5 1 8.6 14.9 7.9 3.5 6.6 7.0 2.3 5.2 1.3 23.3 9.9 19.1 28 21 27 2 1.00
AC6 1 21.2 58.8 11.6 6.8 7.7 6.7 3.4 5.2 1.5 2.7 1.8 2.2 55 17 28 3 2.50
AC7 1 20.0 38.0 6.8 4.8 5.8 7.2 2.9 4.7 1.2 22.3 14.0 18.0 90 0 41 3 1.06
AC8 1 16.0 35.0 9.3 6.6 7.5 5.6 1.7 4.2 1.8 23.0 13.0 19.3 75 40 50 2 1.03
AC9 1 12.0 13.5 8.8 5.1 7.1 6.4 2.1 3.9 1.8 25.0 9.5 18.7 90 60 77 2 1.04