I am interested in the so called alternative developmental pathway of the brachyuran crab Hemigrapsus sanguineus. H. sanguineus is an invasive species in Germany, which can be found on Helgoland (North Sea, German Bight). Under ideal conditions (warm and marine salinity) H. sanguineus develops via six larval stages. The first five are called zoea larvae. The last zoea metamorphoses into the megalopa larva. If the environmental conditions are cold (15°C), some individuals of H. sanguineus develop an additional sixth zoea larva (=alternative pathway). I would like to know, what are the differences in organogenesis between these two developmental pathways. I am interested in the hepatopancreas, the gustatory system and especially the circulatory system and the nervous system (central brain and ventral nerve cord). 

A second question of my PhD concerns the metamorphosis from the zoea in to the megalopa. This metamorphosis is a drastic step in development, because the external morphology of the animal changes tremendously and the internal morphology needs to develop accordingly. An example of such an organ system that must change to fulfill the metamorphosis are the gills and the circulatory system. The latter must form new vessels to supply the newly formed gills in the megalopa. 

A third aspect of my PhD concerns the Organ of Bellonci. An Organ associated with the brain, which function has not yet been clarified. 

To answer these questions, I will use classical histology as well as immunohistochemistry and fluorescence microscopy. The larvae will be reared at the Alfred Wegener Institute (AWI) on Helgoland.