We have referred above to the types of new ocean habitats discovered only within the past two decades: these include those deep-sea communities associated with wood debris, hot and cold hydrocarbon vents and seeps, and entire whale carcasses. Most of these habitats possess suites of species uniquely adapted to the trophic conditions of these ecosystems. Indeed, in some cases, the modern discovery of new habitats, using advanced new instrumentation and sampling techniques, has solved century-old mysteries. Nineteenth-century dredging expeditions, for example, had already collected some species of ``giant'' vesicoymid clams on the deep-sea floor, clams far larger than any other deep-sea bivalves. Now, one hundred and more years later, it is known that these dredge hauls passed over hydrothermal vents!
We have also noted above how elucidation of the species diversity of a system reveals novel ecosystem function: for example, a major group of previously unknown photosynthetic bacteria, the prochlorophytes, may account for up to 40% of open-ocean surface production in some areas, while the realization of the diversity of eubacteria, archaebacteria, and viruses in the ocean opens the door for improved understanding of global marine biogeochemical cycles and energy flow.
Are there undiscovered ecosystems in the ocean? As it seems unlikely that the discoveries of the past two decades represent the last unexplored systems, undoubtedly there is yet novelty at the level of entire ecosystems which awaits discovery. Unfortunately, unlike genetic and species diversity---for which it is now possible to relatively confidently and accurately predict where undescribed diversity exists---the prediction of ecosystem diversity remains elusive. Hydrothermal vents and whale skeletons were ``stumbled upon.'' Once discovered, however, more thorough searching and the establishment of patterns did and can rapidly follow. Some of the guideposts to novel communities may thus be buried in nineteenth century monographs and museum collections. Unusual organisms hauled up from the deep sea, for example, that are unlike anything else seen in the dredge bag for any station before or after, may provide the hint that a passing dredge clipped the corner of a world awaiting visitation again.