Clever Sleuthing Unmasks Mystery Ocean Creature

A mystery animal has been identified as a species never documented in New Zealand waters.

Thousands of specimens were collected during NIWA’s three-week Ocean Census voyage to the unexplored Bounty Trough earlier this year, done as part of a 10-year planetary census to discover life in our ocean.

Watch: the Bounty Trough Ocean Census voyage

Amongst the brilliant selection of fish and invertebrates collected from 3,500m deep, an unusual specimen stumped the experts. NIWA marine biologist and voyage leader Sadie Mills says she and her colleagues resulted to calling it ‘The Thing’.

"It looked kind of like a sea star, but we thought it could also be a sea anemone or octocoral. We had several world-leading experts onboard and none of us could place it, and initial DNA sequencing resulted in no close relationship with any known organism. So, it became known as ‘The Thing’," said Sadie.

However, after further DNA sequencing, Sadie’s team got a positive result - a 98.9% match to Oligotrema lyra - an abyssal ascidian, or sea squirt. Identification was then morphologically confirmed by taxonomic expert, Dr Mike Page.

"It’s amazing that genetics could help us solve the mystery. We actually had two specimens, but it turned out they were both only parts of the whole creature, which is what threw us because we weren’t seeing the full picture. Our resident ascidian expert Mike thinks part of the body was buried in the sediment, and what we collected were the siphons that they use to feed and filter water, which protruded above the sand," said Sadie.

While this species is already known to science, it is the first time it has been documented in New Zealand waters and expands our knowledge on the huge diversity of species that fall under our protection.

Ascidians are common in New Zealand's coastal waters and in the deeper waters on our continental shelf. They are amongst the more colourful marine invertebrates that inhabit our coasts, harbours, and oceans.

When disturbed, sea squirts contract their siphons, expelling streams of water-hence their name.

The Ocean Census is a global alliance to accelerate the discovery and protection of life in the ocean founded by The Nippon Foundation and UK ocean exploration foundation Nekton, and endorsed as a Programme of the UN Ocean Decade.

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