What brings us together at IAFSB is our common research subject, the fish skeleton. At moments we are still surprised that IAFSB meetings work. This is because attending an IAFSB congress is always a little daring: we step out of our trusted science community. Palaeontologists meet and discuss with molecular biologists, aquaculture scientists meet and discuss with colleagues from biomedical research, developmental biologist talk to taxonomists. The way we approach questions in our respective branch of science, our habits and standard protocols are different. That is the challenge and the beauty of IAFSB. The 2009, 2011 and 2013 IAFSB congresses had a bias towards teleost skeletal biology. Thus, we are extremely pleased that the 4^th conference receives a strong contribution from colleagues working on the chondrichthyan skeleton. If one would ask what chondrichthyan skeletal biology can do for zebrafish-based biomedical research, a quotation from Theodosios Dobzahnsky (1973) in his essay "Nothing in Biology makes Sense Except in the light of evolution" provides an answer: "Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes pile of sun-dried facts-some of them interesting or curious but making no meaningful picture as a whole". In that sense we wish all of you an inspiring and fruitful congress, a lot of interesting discussions and perhaps new collaborations across the disciplines. We thank all of you for making IAFSB2015 possible by attending and sharing your thoughts and contributions.

Organizers

M. Leonor Cancela and P. Eckhard Witten

Scientific committee