Research

In the focus of research in the Lower Invertebrates 1 are the morphology and evolution of different animal taxa and different organ systems.

Animal Taxa: There is a primary interest is for taxa Nematomorpha (horsehair worms), Priapulida, Gastrotricha, Tardigrada, Cnidaria und Onychophora. Besides that, current projects deal with chaetognaths (arrow worms), cestodes (tapeworms), gnathostomulids and hirudinens (leeches).

Methods: For morphological investigations, we apply different methods, from histology to scanning and transmission electron microscopy. An inclusion of µCT-analyses is planned. Musculature and nervous system are stained by histochemical (musculature) or immunohistochemical (nervous system) methods and analysed in the confocal laserscanning microscope. When necessary, further methods such asPCR and DNA-sequencing are also applied.

Projects: There is a broad range of projects, the most important ones are presented in the following.

Systematics of Nematomorpha.

The horsehair worms (Nematomorpha) contain about 300 species and only a handful of experts (worldwide) works with them. On the basis of about 2000 specimens investigated from the whole world, an intensive overview on the diversity of this taxon could be gained. About 30 new species were described until now, some genera, such as the species-rich ones Gordius and Chordodes, were investigated intensively. Species determination is usually done by Scanning Electron Microscopy, besides that we are starting to sequence the CO1 gene to characterize species that are difficult to distinguish. There is an intensive collaboration in the NSF (USA) grant "Unraveling a Gordian knot: Biodiversity of Gordian worms, phylum Nematomorpha, in the New World" (www.nematomorpha.net/; principal investigators Ben Hanelt, University of Albuquerque und Matt Bolek, Oklahoma State University).

Architecture of the nervous system of the Cycloneuralia and Gastrotricha.

Within the DFG-focal programme „Deep Metazoan Phylogeny“ our project concentrates on the investigation of the nervous system in Gastrotricha and Cycloneuralia. Up to now, Birgen Holger Rothe investigated a number of gastrotrichs, several priapulids and some kinorhynchs.

Architecture of musculature and nervous system in Tardigrada.

Corinna Schulze investigates the musculature and nervous system in tardigrades, in particular of heterorardigrades.

Structure of the nervous system in other taxa.

Besides the taxa named above, current master and bachelor projects deal with the investigation of the nervous system and/or musculature of Halammohydra (Hydrozoa, Cnidaria), Hymenolepis (Cestoda, Plathelminthes; in collaboration with Peter Olson, Natural History Museum, London) and representatives of the Gnathostomulida (in collaboration with Verena Rieger and Steffen Harzsch, Uni Greifswald).

Diversity of Caribbean gastrotrichs.

Andreas Schmidt-Rhaesa and Birgen Holger Rothe are integrated in the NSF (USA) supported grant „An International Approach to the Biodiversity, Biogeography and Evolution of Caribbean Gastotricha” (http://faculty.uml.edu/rhochberg/NSF/index.htm; principal investigator Rick Hochberg). In this project gastrotrich are systematically collected in the Caribbean region and analysed in respect of their diversity, biogeographical patterns and evolution. In april 2010 a first collecting trip was performed (together with Alexander Kieneke, DZMB Wilhelmshaven) to Lee Stocking Island, Bahamas.

Phylogeny of the Cnidaria – Investigations of statocysts.

The systematics and phylogeny of the Cnidaria have long been object of intensive discussions. In the past, „classical“ anatomical and morphological characters were the main tools, recently applied molecular methods often came to differing results. We investigate the gravity receptors of medusae using histological and electron microscopical methods and, in collaboration with chemists, using crystallographic methods such as powder diffraction, single crystal analysis, micro- and diffraction tomography (SRµCT and DCT) as additional characters for phylogenetic analyses. The focus is on the structure of statocysts and statoliths in different taxa of the Rhopaliophora.

Diversity and Biology of the Onychophora.

Prof. Hilke Ruhberg keeps and investigates since decades onychophorans. Now, during her retirement, she proceeds these investigations, for example integrated in a project about the diversity of onychophorans in South Africa (principal investigator: Dr. Savel Daniels, University of Stellenbosch).