Sebastian Schmelzle

Technische Universität Darmstadt | TU · Research Area of Zoology

Background: Mechanical defenses are very common and diverse in prey species, for example in oribatid mites. Here, the probably most complex form of morphological defense is known as ptychoidy, that enables the animals to completely retract the appendages into a secondary cavity and encapsulate themselves. The two groups of ptychoid mites constitut...

Abstract The most complex mechanical defense of oribatid mites is ptychoidy, in which the animals can retract their legs and gnathosoma into the idiosoma and encapsulate by deflecting the prodorsum. Since Acari lack most antagonistic musculature, extension of appendages is facilitated through hemolymph pressure that in mites mostly is generated by...

Small arthropods show a highly condensed central nervous system, which is accompanied by the loss of the ancestral metameric organization. This results in the formation of one solid mass, a synganglion. Although numerous studies investigated the morphology of Archegozetes longisetosus, the organization of the nervous system is to date unknown. Usin...

Insects evolved various modifications to their mouthparts, allowing for a broad exploration of feeding modes. In ants, workers perform non-reproductive tasks like excavation, food processing, and juvenile care, relying heavily on their mandibles. Given the importance of biting for ant workers and the significant mandible morphological diversity acr...

Most of our knowledge on insect cuticular hydrocarbons (CHCs) stems from analytical techniques based on gas-chromatography coupled with mass spectrometry (GC-MS). However, this method has its limits under standard conditions, particularly in detecting compounds beyond a chain length of around C40. Here, we compare the CHC chain length range detecta...

Synchrotron‐radiation‐based microtomography enables the 3D analysis of biological samples in situ beyond simple visualization, providing accurate measurements and recording of temporal data. The microtomography end station at P05 (PETRA III, Hamburg, Germany), operated by the Helmholtz Zentrum Hereon, can accommodate complex sample environments suc...

We present Biomedisa, a free and easy-to-use open-source online platform developed for semi-automatic segmentation of large volumetric images. The segmentation is based on a smart interpolation of sparsely pre-segmented slices taking into account the complete underlying image data. Biomedisa is particularly valuable when little a priori knowledge i...

One of the largest species in its genus, Odontomachus davidsoni Hoenle, Lattke & Donoso, sp. nov. is described from workers and queens collected at lowland forests in the Chocó-Darién bioregion in coastal Ecuador. The workers are characterized by their uniform red coloration, their large size (16–18 mm body length), and their frontal head striation...

Removing noise in computer tomography (CT) data for real-time 3D visualization is vital to improve the quality of the final display. However, the CT noise cannot be removed by straight averaging because the noise has a broadband spatial frequency that is overlapping with the interesting signal frequencies. To improve the display of structures and f...

The data presented in this article are related to the research paper entitled “The anatomy of the foveola reinvestigated” (Tschulakow et al., 2018) [1]. Here we show the original aligned serial sections through the foveal centre of monkeys at different planes of section and 3 D models of central foveal cells.

Background Oribatid mites are among the primordial decomposer faunal elements and potential prey organisms in soil. Among their myriad morphological defenses are strong sclerotization and mineralization, cuticular tecta, and the “ptychoid” body-form, which allows to attain an encapsulated, seed-like appearance. Most oribatid mites possess a pair of...

Removing noise in computer tomography (CT) data for real-time 3D visualization is vital to improving the quality of the final display. However, the CT noise cannot be removed by straight averaging because the noise has a broadband spatial frequency that is overlapping with the interesting signal frequencies. To improve the display of structures and...

Digitization of natural history collections is a major challenge in archiving biodiversity. In recent years, several approaches have emerged, allowing either automated digitization, extended depth of field (EDOF) or multi-view imaging of insects. Here, we present DISC3D: a new digitization device for pinned insects and other small objects that comb...

Objective In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SC...

3D model shows the parts of the central Müller cells A 3D model shows the parts of the central Müller cells of a monkey foveolar between the plateau zone and the outer limiting membrane. The central Muller cells are bigger and brighter in contrast to the other foveolar cells and the peripheral Müller cells. We used the Amira threshold tool to disti...

A stack of the central retinal section from a monkey fovea A stack of the central retinal section from a monkey fovea is shown with focused ion beam/scanning electron microscopytomographyafter using the Volren tool of Amira software. Müller cells adapt to the shape of the cones including the part containing the nuclei and therefore have a wavy shap...

Transmission of light under the light microscope at different angles A human fovea from an isolated retina shows the transmission of light under the light microscope at different angles. The yellow color represents the macula pigment. Remnants of retinal pigment cells cause the black dots. The optical equipment is shown in Fig. 3C. When the light e...

Stack of sections through the human foveolar center A stack of sections through the human foveolar center is shown. Each line represents an individual section. This stack of sections can be looked through from the top (top left), from the side (top right) or from the front (bottom left). The Müller cells appear as bright cells.

3D model reconstructed from serial sections from the central foveolar cones of a monkey retina A 3D model reconstructed from serial sections from the central foveolar cones of a monkey retina is shown. The 3D model of the central foveolar cones shows that outer segments do not run parallel to the incident light as reported earlier but are curved or...

A stack of the central retinal section from a monkey fovea A stack of the central retinal section from a monkey fovea is shown with focused ion beam/scanning electron microscopy tomography. One view through the stack from the inner segments of cones to the direction of the vitreous (bottom left) and from the front (bottom right) or from the top (to...

3D model of an individual Müller cell An individual Müller cell is shown as a 3D model (Fig. 3B) in the retinal environment of the human foveolar center. Here the Amira Volren view was used and the threshold was adjusted.

Objective. In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (S...

Objective. In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (S...

Modern applications for analysing 2D/3D data require complex visual output features which are often based on the multi-platform OpenGL® API for rendering vector graphics. Instead of providing classical workstations, the provision of powerful virtual machines (VMs) with GPU support in a scientific cloud with direct access to high performance storage...

Beamtime and resulting SRμCT data are a valuable resource for researchers of a broad scientific community in life sciences. Most research groups, however, are only interested in a specific organ and use only a fraction of their data. The rest of the data usually remains untapped. By using a new collaborative approach, the NOVA project (Network for...

Modern applications for analysing 2D/3D data require complex visual output features which are often based on the multi-platform OpenGL® API for rendering vector graphics. Instead of providing classical workstations, the provision of powerful virtual machines (VMs) with GPU support in a scientific cloud with direct access to high performance storage...

The Biomedical Image Segmentation App (Biomedisa) was developed as a semi-automatic tool for improving and accelerating the tedious manual segmentation of computed x-ray tomographic images. It is based on a parameter-free and highly scalable diffusion algorithm, making it easy to use and facilitating the analysis of even large tomographic data sets...

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area - volume (SA/V) ratios for the first time using 3D surface mod...

Oribatida (Acari, Arachnida) are diverse and abundant in temperate forest litter. As particle feeding saprophages or mycophages, their food is of relatively low quality, which supposedly results in slow movement, prolonged generation time and reduced reproductive potential. Hence, oribatid mites developed a number of different defensive mechanisms....

We studied exoskeletal and muscular adaptations to ptychoidy in the oribatid mite Phthiracarus globosus (Phthiracaridae, Phthiracaroidea) using synchrotron X-ray microtomography, and compared the results to Phthiracarus longulus, a closely related mite that we investigated earlier. As expected, both species show high similarity in most of the chara...

Oribatida are one of the main groups of Acari comprising mostly important decomposers in soils. Most species are particle feeders, an exceptional mode of nutrition in Arachnida. Hence, their feeding organs, the gnathosoma, are of special functional interest. We studied nearly all components using scanning and transmission electron microscopies as w...

Oribatida are one of the main groups of Acari comprising mostly important decomposers in soils. Most species are particle feeders, an exceptional mode of nutrition in Arachnida. Hence, their feeding organs, the gnathosoma, are of special functional interest. We studied nearly all components using scanning and transmission electron microscopies as w...

The most complex defensive mechanism in oribatid mites is ptychoidy, a special body form allowing the animals to retract their legs and coxisternum into a secondary cavity in the idiosoma and to seal it off with the prodorsum. Many exoskeletal and muscular adaptations are required to enable the functionality of this mechanism, e.g. a soft and pliab...

Ptychoidy is a mechanical predator defence in some groups of Oribatida (Acari), where the animals can retract their legs into the idiosoma and encapsulate. This mechanism is enabled by a number of morphological adaptations. We used the non-invasive technique of synchrotron X-ray microtomography to compare muscular elements involved in ptychoidy of...

Ptychoidy is a mechanical defensive mechanism of some groups of oribatid mites, in which the legs and coxisternum can be completely retracted into the idiosoma and the prodorsum acts as a seal to the encapsulated animal. Here, we use two microscopical techniques, scanning electron microscopy and synchrotron X-ray microtomography, to compare exoskel...