Examples of benthos include oysters, corals, starfish and clams. Factors such as water temperature, salinity and amount of light drive the composition of benthic communities in a particular area, and they may vary substantially across different geographical regions.
Benthic organisms that live on top of the sand are called epifauna. These animals attach themselves to other objects; examples include sponges, sea squirts and barnacles. By contrast, infauna burrow in the sand. Examples of infauna include razor clams and red ribbon worms. Many of these organisms have adaptations for such a lifestyle, such as bristles or mucus secretions that facilitate movement through the sand.
Because these creatures are often immobile or slow-moving, they filter feed and rely on particulate matter in the water for food. This feeding behavior can make them very ecologically important, as their constant filtering removes debris from the water, leading to improved water quality. They often have defense mechanisms to make up for their slow speed, such as hard shells or venom.
Additionally, by building a hard substrate on the seafloor, benthic organisms create productive habitats where sea life proliferates. These are often hotspots of biodiversity, as in the case of oyster or coral reefs. Benthic organisms are also an important food source for larger aquatic predators.