Sea slugs eat different things depending on the species, but some of their prey includes species of coral, other species of sea slugs, algae, stinging hyoids and cyanobacteria. There are as many as 3,000 different sea slug species in the world that have their own unique prey requirements.

The sea slug is able to avoid predators by hiding in unique ways, such as blending in with its food or only moving around at night when most predators are sleeping. Some sea slugs are also able to dispel toxins that keep predators at bay. Other sea slugs come in bright colors that let predators know that they are toxic.