The Leibniz Institute for the Analysis of Biodiversity Change
is a research museum of the Leibniz Association
Link to Leibniz Association
The Opisthobranchia are beautiful and diverse sea slugs having evolved from shell bearing Prosobranchia. About 5000 to 6000 species are known worldwide. They live in all kind of marine 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, such as the defensive strategies of using highly toxic chemicals from their food or 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 to understand the evolution of the relevant taxa within the Opisthobranchia – the latter not being considered 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, University of Wuppertal) and the relationship of some sacoglossan members with algal chloroplasts (the latter together with the AG of Prof. Dr. W. Martin, University of Düsseldorf).
Also, the uptake of secondary metabolites from food might have enhanced radiation. Therefore, together with Prof. Dr. G. König (Pharmaceutical Biology, University of Bonn), we investigate secondary metabolites from the slugs and their prey.
In addition, the incorporation of cnidocysts from cnidarian prey is assumed to be a key character for the evolution of the nudibranch group Aeolidoidea. We investigate this hypothesis by using histology of the sea slugs as well as of prey organisms and analyse maturation processes of cnidocysts within the slug (cooperation with Dr. Ulf Bickmeyer, Alfred-Wegener-Institut, Bremerhaven).