单选题 .  Towards the end of June, a unique joint expedition began in the waters near Indonesia. In an area of remarkable marine diversity known as the "Coral Triangle", two vessels set sail: the American Okeanos Explorer and the Indonesian Baruna Jaya IV. Their destination was not over the horizon, but to explore the depths of the ocean.
    Jane Lubchenco, administrator of America's National Oceanic and Atmospheric Administration, says this is the first time that scientists have used a remotely operated vehicle to investigate the cold depths of Indonesia's Sangihe Talaud region. Their remotely operated vehicle, known as Little Hercules, is working in waters as deep as 3,700 metres (2.3 miles) and as shallow as 250 metres.
    By several accounts, the diversity of marine life being discovered is phenomenal. Tim Shank, of the Woods Hole Oceanographic Institution and the lead scientist on the expedition, says the team are discovering levels of large-animal diversity that rival anything found in similar habitats elsewhere on the planet.
    Dr. Shank is directing the expedition from a command centre in Jakarta, the Indonesian capital. He says the team have discovered between 30 and 40 new species in the past week of diving alone.
    Little Hercules is cruising over hot springs, deep-sea muds and the rocky tops of seamounts—a kind of underwater mountain that rises from the sea floor. A whole different set of corals live down here—and with them come a specialized fauna (动物群). For instance, two chirostylid crabs have been found that live their adult lives only in one particular black coral. Sea stars, crabs, shrimp and worms are found living in the limbs of these corals as birds and insects do in the branches of trees in a rainforest.
    What is most intriguing is that the team are gathering evidence for the existence of a deep-ocean "Wallace Line". This is an area named after Alfred Wallace, an evolutionary biologist who noticed in the 19th century that the fauna on either side of this line were distinctly different. The line runs between Borneo and Sulawesi, and through the Lombok Strait near Bali. To the west of the line the animals are Asian and to the east of it the species are a mix of Asian and Australian.
    The reason for this line is not entirely understood, says Dr. Shank, but it is thought to be related to the difficulty that species have had in crossing the deepwater under this line. Any confirmation that Wallace's Line extends to the floor of the deep ocean itself will certainly test ideas about the evolution of the region. The mission continues until the end of August.1.  The marine life in the "Coral Triangle" can be best characterized as "______."