epifauna

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Aquatic animals, such as starfish, flounder, or barnacles, that live on the surface of a sea or lake bottom or on the surface of a submerged substrate, such as rocks or aquatic plants and animals, but that do not burrow into or beneath the surface.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A fauna characterized by members whose typical life sites are on the outer surface of their environment, as opposed to within it, e.g. animals living on top of the sediment at the seafloor.