2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

A comparative analysis of all the developmental sequences using an Even-Pairing
approach gives us the first indications of the evolutionary transformation which the
Cladocera may have undergone from a clam shrimp-like ancestor.
�82 Julia Huber A 702 / 14:15
Structure, mineral distribution and mechanical properties of the Pars incisica
cuticule in the mandibles of Porcellio scaber Latreille, 1804.
Authors: Julia Huber 1 , Helge-Otto Fabritius, Andreas Ziegler
Affiliations: 1 Central Facility for Electron Microscopy, University of Ulm, Max Planck
Institute for Iron Research Düsseldorf
The isopod cuticle forms skeletal elements, which properties are adapted to their
function and specific eco-physiological strains. As the main contact surface when
grinding food items the cuticle of the Pars incisiva has to withstand strong abrasive
forces. Using scanning-, transmission- and low-voltage scanning-transmissionelectron
microscopy, elemental analysis and nanoindentation we studied its
structure, composition and mechanical properties. The unmineralized epicuticle of
the tip is unusual thick (50 µm) in comparison to the epicuticle of tergites (200nm).
Towards the middle and the base, the epicuticle narrows from about 5 µm to 3 µm. It
consists of 2-4 layers varying in height and structure. In general, the exo- and
endocuticle of Isopoda consists of chitin-protein fibres organized in a twisted
plywood arrangement and mineralized mainly by calcium carbonate (Hild et al. 2008,
Journal of Structural Biology 163, 100-108). In the middle region of the pars incisiva,
however, the chitin-protein fibers within the exocuticle and distal endocuticle are
parallel oriented, pointing with their long axes towards the cutting-edge. This may
provide higher stability in the direction of maximum load (Nikolov et al. 2010,
Advanced Materials 22, 519-526). In addition, exo- and endocuticle of the middle
region contain phosphorus and calcium in a molar ratio of up to 0.8, suggesting
mineralization by calcium phosphate rather than calcium carbonate.
Nanoindentation reveals that the elastic modulus is very low in the epicuticle, highest
in the exocuticle and intermediate within the endocuticle. Overall the elastic modulus
of the cuticle increases from 0.75 GP at the tip to about 5 GP at the base of the Pars
incisiva.
�83 Hans Peter Katzmann A 702 / 14:30
Comparative SEM studies of the anterior ventral head region in maxillopod and
branchiopod representatives of the Euentomostraca (Crustacea, Entomostraca)
Authors: Hans Peter Katzmann 1 , Andreas Maas 1 , Dieter Waloszek 1
Affiliation: 1 University of Ulm, WG Biosystematic Documentation, Germany
The origin of the arthropod head and affiliation of its ventral appendages has been a
matter of debate in the scientific community for several decades already. Especially
the appendages of the anterior region were subject to considerable dissent among
scientists. Two of the critical structures there are of special interest to us, usually
referred to as hypostome and labrum. The use of these terms is inconsistent, clear
definitions of the terms are lacking. Our current hypothesis is that hypostome and
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