An integrative analysis of olfaction in terrestrial versus marine hermit crabs

• Applicants: Professor Dr. Bill Hansson; Professor Dr. Steffen Harzsch
• Subject Area: Systematics and Morphology (Zoology) ; Sensory and Behavioural Biology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251387201

In parallel to insects, terrestrial Crustacea provide a fascinating chance to participate in a wonderful evolutionary experiment by analyzing which potential alternative solutions arthropods have evolved to explore the terrestrial olfactory landscape. In the current project, we will gain a significantly deepened insight into olfaction and smell-driven behavior of terrestrial versus marine hermit crabs. We will analyze the architecture of peripheral and central olfactory pathways, and of mechanosensory pathways in detail. We will also study the ontogeny of these neural pathways with regard to the larval transition from sea to land. In behavioral assays using all three target species, Pagurus bernhardus (marine), Birgus latro and Coenobita clypeatus (both terrestrial), we will determine olfactory search strategies and key odor cues. Specific goals include to:- quantify the aesthetascs and non-aesthetasc bimodal sensilla in P. bernhardus, B. latro and C. clypeatus by scanning electron microscopy (SEM) and analyze their ultrastructure by transmission electron microscopy (TEM).- reconstruct the 3D architecture of the distal antenna 1 segment (tuft region) in all three target species by serial semithin sectioning to determine the number of olfactory sensory neurons. - provide a 3D reconstruction of the entire olfactory lobe of all three target species based on autofluorescence preparations scanned by confocal laser-scan microscopy, quantify the glomeruli.- explore possible regionalization of the olfactory lobes by single sensillum backfills combined with confocal laser-scan microscopy in all three target species. - study the wiring pattern of OSN axons, local interneurons and projection neurons within the glomeruli by mass- and oligo-backfills of aesthetascs with dextrans (ruby red) and immunohistochemistry against slelected neurotransmitters such as serotonin, histamine, RFamide related peptides, allatostatin, GABA in all three target species.- Analyze the development of central and peripheral pathway in larvae of all three target species to understand how a water nose is ontogenetically transformed into an air nose.- Conduct wind-tunnel bioassays with C. clypeatus to analyze the spectrum of food odors and single components that elicit olfactory-guided behavior and analyze odor tracking strategies under controlled lab conditions.- Investigate olfactory-guided behavior and olfactory navigation strategies to odor sources of C. clypeatus in their natural habitat in the Parque de Cahuita/Costa Rica - Investigate olfactory-guided behavior and olfactory navigation strategies to odor sources of B. latro in bioassays in their natural habitat on Christmas Island/Indian Ocean. - Study odor tracking behavior of the marine hermit crab Pagurus longicarpus using the flume at Georgia Institute of Technology/Atlanta.

• DFG Programme: Research Grants
• International Connection: Australia, Japan, USA
• Participating Persons: Dr. Klaus Anger; Professor Dr. Katsuyuki Hamasaki; Dr. Alexandra Kraberg, Ph.D.; Michael Misso; Professor Dr. Marc Weissburg