Benthic Life

Light micrograph of the benthic foraminifer Nonionella stella, which thrives in anoxic sulfidic sediments far below the euphotic zone. Individuals are ~225 microns in diameter. (Image credit: J.M. Bernhard © Woods Hole Oceanographic Institution)

Benthic ecosystems are communities of organisms that live on or near the ocean floor, also known as the benthic zone. These environments range from shallow coastal regions to the deepest parts of the ocean, and they play a vital role in global nutrient cycling, carbon storage, and biodiversity. Organisms that live in benthic ecosystems include invertebrates like worms, mollusks, crustaceans, and unique single-celled organisms such as foraminifera. Some, like Nonionella stella, thrive in extreme conditions—surviving without oxygen in dark, sulfide-rich sediments far below the sunlit surface.

Despite the lack of light and often harsh conditions, benthic ecosystems are full of life. Hydrothermal vents and methane seeps support communities powered by chemosynthesis rather than sunlight. In these areas, microbes use chemical energy to fuel food webs, supporting everything from tiny bacteria to deep-sea worms and crabs. Ongoing discoveries—such as new worm species off Costa Rica or deep-sea coral reefs in the Galápagos—demonstrate the rich biodiversity found on the seafloor.

Shipwrecks, polar seafloors, and even alien-looking vent sites provide habitats for benthic species, many of which are still being studied. Understanding benthic ecosystems helps scientists monitor environmental change, study evolution, and expand our knowledge of life on Earth—and possibly other planets.