Scientist Feature: Dr Tohru Naruse

 

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Dr Tohru Naruse at the Lee Kong Chian Natural History Museum (LKCNHM). Photo by Chia Han Shen. 

 

“Crabby” Research

When we think crustaceans, we think chilli or black pepper crab and how to satisfy our palates. There are, however, some who think crabs not to fill their appetites but to feed their curiosity.

Ever heard of tree-climbing crabs? Ever wondered just how many crustacean species there are?

Much of what we know about marine biodiversity and oceanic life come from the life work of scientists such as Dr Tohru Naruse, an Associate Professor from the Tropical Biosphere Research Center at the University of the Ryukyus, Japan.

Dr Naruse is a specialist in the study of brachyurans. Brachyurans are a suborder of crustaceans that are referred to as true crabs. These crabs—characterised by a short tail and a reduced abdomen—are amongst Dr Naruse’s passion.

His current project at Lee Kong Chian Natural History Museum (LKCNHM) to document and examine crabs of the genus Labuanium (Family Sesarmidae) is evidence of this. These nocturnal tree-climbing crab species which consume plant and animal matter are found in mangrove forests all over Southeast Asia. To date 13 species have been discovered and described.

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Labuanium trapezoideum (H.Milne Edwards, 1837), a tree-climbing crab specimen being examined by Dr Naruse. Photo by Dr Tohru Naruse.

Dr Naruse’s first visit to Singapore was the day before 11 Sept 2001. Since then, he has been a frequent and well-known visitor to LKCNHM with at least a visit once a year.

His collaboration with the head of LKCNHM, Professor Peter Ng—also an expert in crab taxonomy and biology—has borne much fruit.

This included a 6-month stay studying brachyurans in the museum’s collection, and later as a research fellow at the Department of Biological Sciences from October 2006 to December 2008.

Boyhood Passion

Dr Naruse’s interest in nature stems from a boyhood passion. In his youth, he explored the picturesque mountains and rivers that surrounded his home in Seto City, Aichi Prefecture, on the main island of Honshu, Japan. Here, he would encounter a myriad of insects, freshwater shrimps and fish.

It was only later in his university days that he would discover a genuine passion and deeper appreciation of brachyurans. As an undergraduate student about twenty years ago, Dr Naruse became interested in life found in freshwater and coral reef environments—particularly the crabs and prawns—as he waded through the islands collecting specimens.

Okinawa, an island in Japan’s south, is a tropical island that hosts Pacific coral reefs and is one of the nation’s hotspots for biodiversity. The proximity of the sea to the University of the Ryukyus made it an ideal oceanic research lab right at the doorstep of the university for Dr Naruse.

An independent researcher with the University of the Ryukyus, he enjoys collecting crab specimens from scuba diving around Okinawan waters. More importantly, he enjoys lending his expertise on crab specimens in both Japanese and international partnerships.

When asked about what he liked about the museum he said he “enjoys the company of international researchers” that the museum draws. This builds ties with them and “encourages the exchange of knowledge, information and data collection methods”.

In comparison to crustacean specimens collected from the Ryukyus and the surrounding Japanese maritime waters, Dr Naruse observes that there is “more diversity with crustaceans in Southeast Asia and discoveries in more tropical regions of the Pacific Ocean”.

His most memorable discovery was on an expedition to Christmas Island, Australia, where Professor Ng invited him to join the team from LKCNHM. There the team found a totally new species of crab, Christmaplax mirabillis. The finding on 15 February 2012 led to the team classifying this cave-dwelling species under a new family and genus. It is these finds that inspire Dr Naruse to continue with his research in brachyurans.

Research in brachyurans has taken him to places such as mesophotic zones, which are middle oceanic zones that have low light penetration. This zone ranges from 30-100 m below the ocean surface. Meso means middle and photic means light in Greek.

This research is conducted through technological advances in rebreathers and special diving equipment. With these technological breakthroughs, the opportunities to further understand the deeper depths of the oceans and the inhabitants of these zones have now been opened.

These avenues have made scientific exploration and research all the more tantalising. What exciting discoveries await Dr Naruse! Time can only tell. But what is clear is that this would not be the last time we see him at LKCNHM. We look forward to his return and whetting our appetite with his invaluable contribution in crab research.

 

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