Otter habitats are found as part of the kelp forest ecosystem. Kelp forests are areas which are home to countless other species beside sea otters, including sea urchins, fish, abalone and sea stars. An otter is central to maintaining the nature of kelp forest ecosystems, as they contribute to biodiversity and balance.
Figure from Wilmers et al. 2012. When occurring at ecologically effective densities, sea otters reduce sea urchins, resulting in large kelp standing stocks and high net primary productivity (NPP). (b) When sea otters are absent, urchins decimate kelp stands, resulting in small kelp standing stocks and low NPP.