Riches in the deep sea

18 April 2018 | Research
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One of the crab species found in the deep sea is affectionately referred to as “Big Ears” due to the shape of the distinctive plate protecting its red eyes (Photo: SJADES2018)

A crab with fuzzy spines and blood-red eyes; skinny hermit crabs that live inside twigs and swollen sea anemones; a giant sea cockroach 30cm in length and a tulip-like sponge anchored to the ocean floor by a one-metre twisted tuft of glass fibres. These are just some examples of the more than 12,000 bizarre creatures belonging to 800 species discovered by the team of Singaporean and Indonesian scientists during the 14-day South Java Deep-Sea Biodiversity Expedition. The 31-man research team, co-led by Professor Peter Ng, Head of the Lee Kong Chian Natural History Museum at NUS and Professor Dwi Listyo Rahayu, Senior Research Scientist at the Research Center for Oceanography of the Indonesian Institute of Sciences, uncovered over a dozen new species of hermit crabs, prawns, lobsters and crabs, and over 40 new records for Indonesia.

In total, the researchers sampled 63 stations over a distance of 2,200km, sailing anticlockwise from Muara Baru, Jakarta in Indonesia towards Cilacap in Southern Java and back, covering depths of up to 2,100m.

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The expedition unearthed more than 12,000 creatures belonging to 800 species 

Three new species of spider crabs were found during the expedition, measuring between 6cm and 8cm. One has a distinctive plate protecting its eyes which resembles oversized ears, leading to its affectionate name of “Big Ears”, another rarer one is bright orange with many strong spines; and a third is likely to be associated with deep-sea stalked sea lilies. These three types of crabs are thought to belong to the genus Rochinia which currently comprises over 30 species, said Prof Ng and deep-sea expedition veteran Dr Bertarand Richer de Forges, who have studied this group of spider crabs for over three decades.

A particularly beautiful species of hermit crab was also found, boasting bright green eyes and distinctly patterned granulated pincers. This hermit crab is likely to belong to the genus of Paguristes, said Professor Rahayu, who is considered to be the world authority on this group of hermit crabs. She immediately recognised the species as one she had never seen before.

One new species of shrimp not seen previously is exquisitely sculptured with shiny eyes that reflect light. These bottom dwelling creatures have unique mechanisms which allow them to lock their abdomens for protection against predators.

Besides animal specimens, the researchers also preserved deep-sea mud to search for meiofauna, creatures of approximately 40 microns in size.

On the research front, our teams have learnt a lot about how to conduct deep-sea science and handle the various equipment needed for such work, and we had the opportunity to sample and examine a multitude of fantastic deep-sea animals.

However, these amazing discoveries did not come without trials and challenges. When the team set off, it was on the tail end of a cyclone, and the rough seas resulted in seasickness for at least half the team on the first day. However this was a small challenge compared to the terrain.

The inaccuracy of the available maps of Southern Java made things complicated. “Most of the depths given on the map were wrong, most of the details were not accurate,” said Prof Ng. That led to sudden dips in the terrain that caused tears and breaks in their trawls and nets. Many nights saw the team test their sewing skills by mending the tears.

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The team discovered a new species of a giant sea cockroach which was 30 cm in length (Photo: SJADES2018)

The 14 days of shared challenges enabled the researchers to forge strong bonds which will be important to the long-term scientific ties between the two countries, said Prof Ng.

“On the research front, our teams have learnt a lot about how to conduct deep-sea science and handle the various equipment needed for such work, and we had the opportunity to sample and examine a multitude of fantastic deep-sea animals. We expect to identify more new species among the pickings of the expedition, and we certainly look forward to studying the specimens and data with our Indonesian friends,” he added.

Prof Rahayu said that the expedition was partly a capacity-building exercise for their young scientists, adding that the Indonesian scientists benefitted both personally and professionally from the experience. “Through interacting with international scientists, they were exposed to new scientific techniques and methodologies in an environment that presents a different set of challenges from their own scientific specialities. Hopefully, such knowledge transfer and collaboration will build stronger and more resilient ties between our two nations,” she said.

See press release.

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At a depth of between 500m to 1,200m, the team found an unusual wood-dwelling deep-sea star (Photo: SJADES2018)