2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

labrum are two different, but closely allied structures: The labrum is hereby a more
sclerotized and bulged plate extending from the rear of the hypostome and
overhanging the recessed mouth. Sometimes the labrum bears chemo-sensillae, the
openings of slime glands and fine hairs laterally and distally, indicating the use of the
labrum in food handling, ingestion and in grooming of the anterior appendages. The
labrum has been in the focus of various molecular and developmental studies over
the last years, but none of these studies have considered its morphological and
structural appearance in detail so far. In our study we are investigating the anterior
ventral head region of representatives of several crustacean groups, such as
Cirripedia, Copepoda, Ostracoda, Cephalocarida, Anostraca and Phyllopoda (all
belonging to the Entomostraca), using scanning electron microscopy. We are
comparing the different surface structures in order to distinguish between those
belonging to the hypostome and those belonging to the labrum, in order to shed light
on the functional significance of these structures and the distinction of the two head
parts.
�84 Sukhum Ruangchai A 702 / 14:45
Local variations of cuticular architecture in the basis joint head of Porcellio scaber
peraeopods
Authors: Sukhum Ruangchai 1 , Christian Reisecker, Sabine Hild, Andreas Ziegler 1
Affiliation: 1 University of Ulm; 2 Johannes Kepler University of Linz
The cuticle of crustaceans is an interesting model for the study of structure-function
relationship in biological composite materials because of the hierarchical
organisation of its organic matrix, which is generally arranged in a twisted plywood
structure, and variations in type and phase of the mineral compound. In our study
the basis’s joint head of Porcellio scaber Latreille, 1804 was chosen due to its
apparently different function from the tergite, which was already studied in detail.
Our results show that the cuticle architecture of the joint head has local variations in
structure and composition. In the central region the joint head cuticle is similar to
that of the tergite. However, towards the edges, where the cuticle is connected to
the flexible arthrodial membrane, the epi- and exocuticle are much thicker. The
endocuticle remains as thick as in the central region but, interestingly, the chitinprotein
fibrils run parallel to one another forming no twisted plywood structure. The
mineral distribution in the central region is also similar to that in tergites, with calcite
located distally and amorphous calcium carbonate (ACC) more proximally. Higher
amounts of phosphate are located in the endocuticle suggesting the coexistence of
ACC and ACP (amorphous calcium phosphate). In the edge region phosphate in the
distal exocuticle is as high as that in the endocuticle at a cost of diminishing calcium
carbonate. The overall difference in the cuticular architecture of the edge in
comparison to the central region might be an adaptation to different mechanical
strains it has to sustain and due to the structural transition from the edge to the
connecting arthrodial membrane.
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