Abstract:Webspinners (Insecta: Embioptera) have a distinctly unique behaviour with related morphological characteristics. Producing silk with the basitarsomeres of their forelegs plays a crucial role in the lives of these insects – providing shelter and protection. The correlation between body size, morphology and morphometrics of the spinning apparatus and the spinning behaviour of Embioptera was investigated for seven species using state-of-the-art methodology for behavioural as well as for morphological approaches. … Show more
“…The overall morphology of a spinning gland in Embioptera consists of three major structural units: the reservoir, a syncytial gland cell and the ejection apparatus [5]. The reservoir is a cuticular structure in the centre of the gland (figure 1).…”
Section: Resultsmentioning
confidence: 99%
“…4 b,c in Büsse et al . [5]) where the silk is released for spinning (raw data at dryad: doi:10.5061/dryad.vk3fg10.5061/dryad.vk3fg). Figure 3.The canal cage of the ejection apparatus is a unique feature of Embioptera.…”
Section: Resultsmentioning
confidence: 99%
“…[31] established this technique in insect morphology in 2002. µCT combines user friendliness with powerful computational applications to study small- to medium-sized insects. Meanwhile, there are numerous comprehensive studies investigating each tagma of insects: insect head [32,33], insect thorax [27,34], insect abdomen [35,36] and even smaller body parts [5,37]. The advantages of μCT are that it is non-invasive, comparatively rapid, almost free of artefacts, and allow for a three-dimensional reconstruction at convenient nanotomographical resolutions less than 0.1 µm [21] depending on the set-up used for data acquisition.…”
Section: Discussionmentioning
confidence: 99%
“…At the same time, spinning apparatuses are diverse with respect to their morphology and can be present on a wide range of body parts [1,2]. Spiders, for example, use spigots that are located at their opisthosoma to produce a distinct thread [3], whereas the spinning organs of webspinners (Embioptera) are located in their forelegs [4,5]. Based on phylogenetic cladograms spinning apparatuses evolved many times independently within the arthropods [2].…”
Section: Introductionmentioning
confidence: 99%
“…The embiopteran spinning apparatus has already been studied to some extent [4,5,11–18]. Morphological studies, however, ask questions with respect to texture, composition and organization of a structural character.…”
Spinning is a phenomenon not only present in spiders, but also in many other arthropods. The functional morphology and complexity of spinning organs is often poorly understood. Their elements are minute and studying them poses substantial methodological difficulties. This study presents a three-dimensional reconstruction of a silk gland of Embia sp. on cellular level, based on serial sections acquired with serial block-face scanning electron microscopy (SBFSEM) to showcase the power of this method. Previous studies achieved either high resolution to elucidate the ultrastructure or satisfying three-dimensional representations. The high-resolution achieved by SBFSEM can be easily used to reconstruct the three-dimensional ultrastructural organization of cellular structures. The herein investigated spinning apparatus of Embioptera can be taken as an example demonstrating the potential of this method. It was possible to reconstruct a multinucleated silk gland containing 63 nuclei. We focused on the applicability of this method in the field of morphological research and provide a step-by-step guide to the methodology. This will help in applying the method to other arthropod taxa and will help significantly in adapting the method to other animals, animal parts and tissues.
“…The overall morphology of a spinning gland in Embioptera consists of three major structural units: the reservoir, a syncytial gland cell and the ejection apparatus [5]. The reservoir is a cuticular structure in the centre of the gland (figure 1).…”
Section: Resultsmentioning
confidence: 99%
“…4 b,c in Büsse et al . [5]) where the silk is released for spinning (raw data at dryad: doi:10.5061/dryad.vk3fg10.5061/dryad.vk3fg). Figure 3.The canal cage of the ejection apparatus is a unique feature of Embioptera.…”
Section: Resultsmentioning
confidence: 99%
“…[31] established this technique in insect morphology in 2002. µCT combines user friendliness with powerful computational applications to study small- to medium-sized insects. Meanwhile, there are numerous comprehensive studies investigating each tagma of insects: insect head [32,33], insect thorax [27,34], insect abdomen [35,36] and even smaller body parts [5,37]. The advantages of μCT are that it is non-invasive, comparatively rapid, almost free of artefacts, and allow for a three-dimensional reconstruction at convenient nanotomographical resolutions less than 0.1 µm [21] depending on the set-up used for data acquisition.…”
Section: Discussionmentioning
confidence: 99%
“…At the same time, spinning apparatuses are diverse with respect to their morphology and can be present on a wide range of body parts [1,2]. Spiders, for example, use spigots that are located at their opisthosoma to produce a distinct thread [3], whereas the spinning organs of webspinners (Embioptera) are located in their forelegs [4,5]. Based on phylogenetic cladograms spinning apparatuses evolved many times independently within the arthropods [2].…”
Section: Introductionmentioning
confidence: 99%
“…The embiopteran spinning apparatus has already been studied to some extent [4,5,11–18]. Morphological studies, however, ask questions with respect to texture, composition and organization of a structural character.…”
Spinning is a phenomenon not only present in spiders, but also in many other arthropods. The functional morphology and complexity of spinning organs is often poorly understood. Their elements are minute and studying them poses substantial methodological difficulties. This study presents a three-dimensional reconstruction of a silk gland of Embia sp. on cellular level, based on serial sections acquired with serial block-face scanning electron microscopy (SBFSEM) to showcase the power of this method. Previous studies achieved either high resolution to elucidate the ultrastructure or satisfying three-dimensional representations. The high-resolution achieved by SBFSEM can be easily used to reconstruct the three-dimensional ultrastructural organization of cellular structures. The herein investigated spinning apparatus of Embioptera can be taken as an example demonstrating the potential of this method. It was possible to reconstruct a multinucleated silk gland containing 63 nuclei. We focused on the applicability of this method in the field of morphological research and provide a step-by-step guide to the methodology. This will help in applying the method to other arthropod taxa and will help significantly in adapting the method to other animals, animal parts and tissues.
Limb proportions have evolved among animals to meet functional demands among diverse environments. Studies from terrestrial, vertebrate locomotion have demonstrated that variation in limb proportions have adaptively evolved so animals can perform in a given environment. Most of the research on limb proportion evolution is among vertebrates and terrestrial locomotion, with little information on limb segment evolution in invertebrates or for other functional roles. For example, among invertebrates, multisegmented raptorial forelimbs have evolved multiple times independently to capture prey, but there is little information on the adaptive evolution and diversity of these limbs. Furthermore, as feeding performance is influenced by the sensory system, few studies have examined the coevolution of sensory-motor systems. Using mantises (Mantodea) I examined forelimb diversification among 97 species with a combination of methods, including ternary plots for morphospace visualization, phylogenetically informed allometric relationships, and comparison of evolutionary rates of diversification. Furthermore, using head width as a proxy for depth perception, I examined the correlated evolution of foreleg diversity with depth perception. The results show that among the three segments of the foreleg, the tibia is the smallest, most diverse, and has the highest rate of evolution after body size corrections. Furthermore, while all foreleg segments were related to head width, head width explained the most variation in tibial length compared with other foreleg segments. The results suggest a potential adaptive functional role of tibia length related to the displacement or force produced in this mechanical lever. Furthermore, results from this study support distinct ecomorphs of mantises, as several independent evolutions to grass mimicry evolve similar morphologies.
Research highlightThis study demonstrates interspecific variation among segments of an invertebrate raptorial foreleg. Among Mantodea species the tibia is the most diverse and is related to a proxy for depth perception, while the other segments had strong relationships with body size. This suggests an adaptive, functional role of the tibia during prey capture.
K E Y W O R D Secomorph, evolutionary morphology, praying mantis, raptorial appendage
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