The Zoological Research Museum Alexander Koenig
is a research museum of the Leibniz Association
Link to Leibniz Association
The Opisthobranchia are known as beautiful sea slugs, having evolved from shell bearing Prosobranchia. About 5000 to 6000 species are known worldwide. They live in all kind of habitats, from the intertidal to the deep sea, from the polar regions to the tropical reefs.
Some species do not exceed a length of 5 mm, the largest can grow up to one meter. Many of them are specialists on certain food species. Some groups have specialized on algae, others on poriferans or corals. Some taxa are rather rapacious and a few even prefer to prey on congeners.
The Opisthobranchia are quite famous for many unique biological phenomena, as there are the defensive strategies by using highly toxic chemicals from their food, or by incorporating the stinging cells of cnidarian prey and using them against possible predators. Some of the opisthobranchs are so toxic, that they are mimicked by other invertebrates.
Another unique character for a certain group is the possibility to incorporate chloroplasts from their algal food and to use these as metabolite suppliers. Less spectacular, but nevertheless very interesting is the symbiotic relationship of certain groups with unicellular algae from corals.
The major aim of our projects is the understanding of evolution of the relevant taxa within the Opisthobranchia – the latter not being monophyletic anymore according to latest studies.
The methods we use are morphological and histological investigations, supported by ultrastructural analyses, as well as molecular systematics.
Preliminary results on phylogeny allowed the specification of certain key characters which probably enhanced higher speciation rates in a few taxa. Therefore we are investigating now in more detail the evolution of a high efficient mutualistic relationships between certain nudibranch taxa and zooxanthellae (cooperation with Prof. Dr. G. Preisfeld and Dr. S. Bleidissel, Wuppertal) and the relationship of some sacoglossan members with algal chloroplasts (the latter together with the AG of Prof. Dr. W. Martin, Düsseldorf).
Also, the uptake of secondary metabolites from food might have enhanced radiation. Therefore, together with Prof. Dr. G. König (Pharmaceutical Biology, Bonn), we investigate secondary metabolites from the slugs and the prey.
The incorporation of cnidocysts from cnidarian prey is also assumed to be a key character for the evolution of the nudibranch group Aeolidoidea. We investigate these by histology of the slugs as well as of prey organisms and analysed maturation processes of cnidocysts within the slug (cooperation with Dr. Ulf Bickmeyer, Alfred-Wegener-Institut, Bremerhaven).