Since all life has evolved from a single ancestor, scientists use animals to study how human bodies function. For example, we can use the fruit fly to study eye development in humans. One of the most popular model organisms scientists use is roundworm Caenorhabditis elegans. Professor Daniel Starr at UC Davis uses C. elegans to study nuclear migration, the process of how the nucleus positions itself within the cell. C. elegans is only 1 mm long with 959 cells whereas humans have trillions of cells. The simplicity of model organisms allows researchers to track the cellular processes more easily. Once they understand how the cellular development happens in invertebrates, researchers can use what they’ve learned to run similar experiments in vertebrate model organisms.

The purpose of using model organisms is to learn how to treat and prevent diseases. For example, to study regeneration, scientists have used the immortal Hydra vulgaris. Hydra is a freshwater invertebrate with tentacles that renews its cells every 20 days. This means that it doesn’t age or die. In fact, if you blended up the animal and separated all of its cells, mixed them up, and clumped them back up randomly into a ball, a new Hydra will grow out from it. Experimenting with Hydra allows us to understand the different genetic programs that trigger cellular regeneration.