Discovery, a remotely-operated vehicle (ROV) Discovery aboard China's research vessel Kexue (Science), captured two rare deep-water sea slugs in the Western Pacific Ocean in a recent dive.

Sea slugs are hardly seen in deep-water (deeper than 200 meters), but Discovery gathered the two at a depth of 970 meters, according to Xu Kuidong, chief scientist aboard the vessel and a researcher with the Chinese Academy of Sciences (CAS).

The sea slugs, with white bodies and pairs of bronze tentacles on pink heads, are about five centimeters long and two centimeters wide, but they curled up after being taken to the vessel.

With varying levels of resemblance to terrestrial slugs, sea slugs actually belong to the family of snails, or marine gastropod mollusks, and have lost their shells over evolutionary time.

There are about 3,000 species of sea slugs in the world, mostly found in the shallow water of tropical zones.

Eight species were discovered in the deep-water of northeastern Pacific Ocean, and none has been reported in the deep-water of western Pacific Ocean before.

Beside sea slugs, Discovery has also collected more than 60 samples of corals, sponges, shrimps and rocks in the dive.

The Chinese vessel Kexue is carrying out a 20-day investigation over a series of seamounts in the south of the Mariana Trench, the deepest place on the earth.

(Cover: CCTV Photo)

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