Functional morphology and Phylogeny of Chelicerates
My main research interest is the evolution of body organisation. In segmented organisms, such as arthropods (insects, myriapods, spiders and relatives, crustaceans, but also numerous extinct groups) several segments form a functional unit, a tagma; their body is thus organised into so-called tagmata. The subdivision of the arthropod body (= tagmatisation) changes in the course of evolution.
The most obvious tagma is the most anterior one, the head. During evolution more and more segments have become incorporated into this tagma. My studies have demonstrated that even this obvious tagma is not well-understood. Even in apparently well-studied groups such as mantis shrimps, the composition of the head, as well as that of other tagmata differs from what is usually expected if closely investigated with up-to-date imaging techniques.
Extinct organisms, in the form of fossils, offer insights into morphologies no longer represented in the modern fauna, and often provide “evolutionary steps in between”. With this, the character evolution in different evolutionary lineages can be reconstructed with smallest steps, resulting in finely graded evolutionary scenarios of the increasing specialisation of functional units during evolution.
Currently, I am studying mainly different representatives of chelicerates: spiders, scorpions and their relatives. While these are generally thought to possess two well defined tagmata throughout the entire group, the segmental composition of the tagmata appears to vary between the different sub-groups of Chelicerata.
Prof. Dr. C. Haug / Prof. Dr. M. Heß