Brittle stars live on spiny sponges and other sessile animals in massive fields on the muddy seafloor, as well as by themselves or in abundance directly on the seafloor. Different species of brittle stars eat in different ways—some are suspension feeders and eat food particles suspended in the water; some are deposit feeders and feed on organic particles that settle on the seafloor; and some are active predators, detecting food by its odor.
Anything that finds its way into the ocean, whether it's tossed away as trash, washes off a beach or falls off a boat, may eventually make its way to the deep sea. It's important to realize that the deep sea is not so far away that it's beyond the reach of human activities. Living creatures in the deep are affected by what we do at the surface.
There are around 2,000 species of brittle star—more than any other group of sea stars.