 What would modern biology be without its model organisms? To give just a few examples: Classical genetics was developed mainly by experimenting with fruit flies of the species Drosophila melanogaster. The same organism has recently also been at the center of much exciting work in developmental biology, together with the nematode Caenorhabditis elegans and the zebrafish Danio rerio. Molecular biologists were initially mostly working with the bacterium Escherichia coli and bacteriophage (viruses that infect bacteria). Neuroscientists owe much to the squid with its giant axons. For immunology, the mouse Mus musculus has proven invaluable. Plant molecular biology’s favorite is Arabidopsis thaliana. Cell biology has found in baker’s yeast Saccharomyes cerevisiae an organism that is as easy to breed as E. coli, but its cells are more similar to animal and human cells. This list could go on, but not forever. Compared to field biology, the number of species that are being studied in the experimental life sciences is quite small; so small, in fact, that for most of these model organisms complete genomic DNA sequences are available today.