149 New Deep-Sea Species Discovered at Remote Indian Ocean Seamounts
A deep-sea sea cucumber. The Indian Ocean expedition identified 149 new species, including a sea cucumber from the genus Oneirophanta. Image: NOAA Office of Ocean Exploration and Research (public domain).
An expedition to unexplored seamounts near the Christmas and Cocos (Keeling) Islands has identified 149 previously unknown marine species — plus a 'Shark Tooth Graveyard' holding more than 22 million years of evolution.
The Indian Ocean is a blind spot for deep-sea science. It covers roughly a fifth of the world's ocean, and 90% of it plunges deeper than 1,000 metres — yet compared with the Pacific and Atlantic, its abyssal life is barely documented. A new study has just filled in one of the biggest gaps.
An international team surveying unexplored seamounts near the remote Christmas and Cocos (Keeling) Islands — volcanic peaks rising from the seafloor southwest of Jakarta, between Australia and Sri Lanka — has identified 149 previously unknown marine species in a single set of expeditions.
What they found
The new species include black corals, sea worms, sea cucumbers, and several kinds of fish. Among the standouts:
- A deep-sea sea cucumber from the genus Oneirophanta
- A new greeneye fish (Chlorophthalmus), named for the reflective green lenses that help it hunt in near-total darkness
- A parasitic barnacle from the genus Rhizolepas, which lives attached to other deep-sea creatures
The survey reached depths between 94 and 5,431 metres (308 to 17,818 feet) — cold, dark, high-pressure water where food is scarce and every organism is adapted to extremes.
The "Shark Tooth Graveyard"
The expedition's most striking discovery wasn't a living animal at all. At a site the team nicknamed "The Shark Tooth Graveyard", researchers recovered around 1,000 fossilised shark teeth scattered across the Cocos Abyssal Plain — a collection spanning more than 22 million years of evolution. Many of the teeth had grown manganese nodules, mineral-rich lumps that take millions of years to form on the seafloor, effectively dating the deposit.
Why these mountains matter
The seamounts themselves are ancient. Volcanic in origin, they are 40 to 120 million years old, and some stretch up to 70 kilometres (43 miles) across. Until now, no one had looked at what lives on their deep slopes.
"People had been around the islands in shallow water before, but no one had looked at life in the deep. It was a massive hole in the data," study lead author Tim O'Hara, a marine scientist at Museums Victoria in Melbourne, told Mongabay.
The work, published in the journal Deep-Sea Research Part II in June 2026, drew on researchers from institutions in Australia, New Zealand, Canada and the United States.
What's at stake
Deep-sea research is slow, expensive and logistically punishing — but scientists argue it has never been more urgent. Seamount ecosystems face growing pressure from ocean warming, pollution, overfishing and the looming prospect of deep-sea mining.
Each new species is more than a catalogue entry. Seamounts act as nurseries and refuges for life that connects to the shallows, and deep-sea organisms are a largely untapped source of chemical and medicinal novelty. We can't protect what we don't know exists — which is exactly why expeditions like this one matter.
Want to see more discoveries like this? Browse our Marine Life articles or read our earlier coverage of the Ocean Census 2026.
Written by GeckoDive Team
The official GeckoDive team sharing diving knowledge, gear reviews, and destination guides.