What kind of organisms are considered benthic fauna?

Benthic fauna refers to the variety of organisms that live on, in, or near the bottom substrates of a body of water. This includes various species such as crabs, worms, and other invertebrates that inhabit the sediment and rocky environments at the bottom of lakes, rivers, and oceans. These organisms play a crucial role in the aquatic ecosystem by contributing to nutrient cycling, providing food for other species, and influencing the physical structure of the habitat.

The definition of benthic fauna specifically relates to the organisms that occupy the benthic zone, which is the ecological realm at the bottom of a water body. This indicates that organisms found in this category are adapted to life on or within the substrate rather than in the water column or above the surface. Such adaptations might include specialized feeding mechanisms, body shapes, and life cycles suited to their benthic environment.

Other choices describe organisms that do not inhabit the benthic zone. Fish swimming near the surface and birds feeding on insects are examples of organisms associated with different habitats, such as the pelagic zone (open water) for fish and terrestrial environments for birds. Algae and seaweed, although important in aquatic ecosystems, are typically considered part of the water column or attached to surfaces rather than part of