In 2009 the scientists collected about 7000 samples including the newly discovered squid, which has light-producing organs that it uses to attract its prey.
Researchers aboard the RRS James Cook are taking along special cameras for photographing the ocean floor - something they didn't have last time.
"We don't know much about the deep sea community," Aurelie Spadone, a sea specialist with the International Union for Conservation of Nature (IUCN), said yesterday. "It would be very surprising if we don't find something like a new species."
The trip is focused on learning more about how deep sea fishing is affecting marine life along seamounts - peaks rising from the floor of the southern Indian Ocean.
Carl Gustaf Lundin, director of IUCN's global marine and polar programme, said many of the species that live around seamounts grow and reproduce slowly, so overfishing can severely affect their populations.
"Deep-sea bottom fisheries, including bottom trawling, can damage seamount habitats and negatively impact fish stocks," he said. "It can also irreversibly damage cold water corals, sponges and other animals."
Oxford University's Alex Rogers, the expedition's chief scientist, said the goal was to better understand a unique underwater environment and the threats it faces.
"Based on what we learn by studying five seamounts in the southwest Indian Ridge, we're hoping to get a better idea of where special habitats, such as cold water coral reefs, occur and how we can protect them in the ocean globally," he said. "Perhaps we'll also be lucky enough to discover some new species living in these virtually unknown waters."