2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

In order to gain more data regarding patterns of neural and muscular redevelopment
in annelids, we analyzed different stages of anterior regeneration in
Chaetozone caput-esocis (Cirratulidae, Sedentaria, Annelida) by using
immunocytochemical staining techniques combined with subsequent confocal laser
scanning microscopy (cLSM). With focus on different stages of anterior regeneration
in adult specimens, we used neuronal antibodies (e.g., against serotonin and
FMRFamide) and muscular markers (phalloidin) to reconstruct the process of tissue
and body formation after decapitation. Our investigations help to understand basic
patterns of reorganization within annelid organ systems and provide fundamental
knowledge for further investigations. Here we present a summary of our findings and
draw conclusions regarding basic regenerative patterns of Annelida in general.
����114 Angelina Bösemann
Body stalk morphology and cell dynamics of the carnivorous sponge
Asbestoplumahypogaea during starvation, prey capture and digestion
Authors: Jörg U. Hammel 1 , Angelina Bösemann 1 , Felix Beckmann 1 , Jean Vacelet 1 ,
Michael Nickel 1
Affiliation: 1 Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich-Schiller-
Universität Jena
The carnivorous sponge Aspestopluma hypogaea Vacelet & Boury-Esnault, 1996
(Demospongiae, Poecilosclerida, Cladorhizidae) lacks a canal system. Instead of
filtering particulate organic matter like other sponges, it feeds upon small
crustaceans which are caught by microscleres on the surface of long dynamic body
filaments. The millimeter-sized club shaped body of A. hypogaea sits on a centimeterlong
thin stalk which anchors the sponge upon the hard substrate in a relatively small
disc-like holdfast structure. While the morphology and dynamics of the preycapturing
filaments during starvation, prey capturing and digestion is well known, the
role of the body stalk has not been investigated before. Recent time-lapse imaging
series revealed a high cellular dynamics within the stalk with a bi-directional cellular
traffic between the stalk and the body. The aim of the present study is to understand
the functional morphology of the stalk under its constraints to mediate stability and
to allow for nutrient transfer between sponge body and holdfast. We used time-lapse
imaging, histology, SEM, cLSM and SR-µCT to characterize body and cell dynamics as
well as anatomical traits in 2D and 3D. Our preliminary results characterize the stalk
as structure highly stabilized by macroscleres, collagen, the pinacocytes and
eventually other positionally stable cell types. Spherulous cells seem to be the most
prominent motile cell type. Bi-directional movement of cell clusters at velocities of
205 µm h-1 (±36 µm h-1) occurs simultaneously regardless of the feeding state.
However we found a tendency during digestion for increased downstream movement
towards the holdfast.
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