Keystone species
![The jaguar, an example of a keystone species](/Images/godic/202501/22/Junior-Jaguar-Belize-Zoo1920.jpg")
![Cluster of ochre sea stars (Pisaster ochraceus) - keystone predator.](/Images/godic/202501/22/Ochre_sea_stars1920.jpg")
![Aggregation of California mussels (Mytilus californianus) - prey species.](/Images/godic/202501/22/California_Mussels_0021920.jpg")
![Sea urchins like this purple sea urchin can damage kelp forests by chewing through kelp holdfasts](/Images/godic/202501/22/Seaurchin_3001920.jpg")
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Such species are described as playing a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community.