All modern life arose from a common ancient ancestor. From yeast and worms to fruit flies and mice, many creatures hold clues to the secrets of our own biology. For example, the gene networks that govern eye development in fruit flies are similar to those found in mammals, which makes it possible to study human eye development using fruit flies! Because of this, these animal models – called "model organisms" – are used to build the foundation for revolutions in human health.
![Fruit fly](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Fruit-Fly-College-of-Biological-Sciences-UC-Davis_1.jpg?itok=_1J1vpub)
Fruit Fly (Drosophila melanogaster)
Phylum: Euarthropoda
![Garden Tomato](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Tomato-College-of-Biological-Sciences-UC-Davis.png?itok=TuKbIcEW)
Garden Tomato (Solanum lycopersicum)
Phylum: Spermatophyta
![House mouse](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Mouse-College-of-Biological-Sciences-UC-Davis.png?itok=6-dOUSmh)
House Mouse (Mus musculus)
Phylum: Chordata
![Hydra](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Hydra-College-of-Biological-Sciences-UC-Davis-crop.jpg?itok=aLk_FL8u)
Hydra (Hydra vulgaris)
Phylum: Cnidaria
![Roundworm](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Roundworm-College-of-Biological-Sciences-UC-Davis.png?itok=dZP-9NRk)
Roundworm (Cenorhabditis elegans)
Phylum: Nematoda
![Zebrafish](/sites/g/files/dgvnsk16761/files/styles/sf_small_width/public/media/images/Zebrafish-College-of-Biological-Sciences-UC-Davis_0.png?itok=zfKUvSpa)
Zebrafish (Danio rerio)
Phylum: Chordata