Kanchanaburi in eastern Thailand borders Myanmar and is home to interesting fish species, so I often go there to photograph and collect fish. However, Kanchanaburi is quite large, and the main place I go for fieldwork is Sangkhlaburi, the westernmost part of Thailand. It takes about 5 hours or more to get here by car from Bangkok. First, we drove for three hours to the city of Kanchanaburi, and then drove for another hour towards the mountains to arrive at a place called Thong Pha Phum. Since it's a long drive, I often stop in this town for a short break or check out the market. There is a large crab monument at the entrance to the town, which is sure to catch your eye. The first time I visited this town was over 15 years ago, and I have fond memories of taking a commemorative photo in front of the Queen Club statue. At that time, I heard about this crab, and as a crustacean lover, I wanted to visit its habitat someday.

The scientific name of this crab is Thaiphusa sirikit, and the species name is named after Queen Sirikit of Thailand. The stone inscription at this monument says that it is called the Regal Crab in English, but in reality Thai people more commonly call this crab the Queen Crab. In Thailand, the royal family is highly respected, and the people affectionately call this crab Phu Rachni. Phu means crab in Thai, and rachini means queen.

This species was described as Demanietta sirikit in 1992, but the genus name was later changed to the current genus. In 1994, it was featured on a Thai stamp along with three other freshwater crab species.

It was July about six years ago, right in the middle of the rainy season in Thailand. I also had the opportunity to stop by Tonpapun for work. I had heard that this is the best time to observe the Queen Crab, so I decided to go and take some photos. However, the habitat seems to be quite far from town, making it difficult to find a guide. Through an acquaintance, I managed to reach a local ranger and asked him to show me around. Its habitat was deep in the mountains, a place that ordinary tourists would never go, and could only be reached by driving for a while along an unpaved mountain road. I would never have been able to get there on my own. There is a sign in Thai indicating where it lives, and a boardwalk has been built above the wetland for people to walk to observe it, but it is dilapidated and has potholes here and there, so be careful. It's quite dangerous without it.

While I was doing this, the old ranger suddenly signaled me not to talk. When I looked in the direction I was pointing, I saw Queen Crab wearing white and red! Although it is still daytime, they seem to be active during the daytime as well when there is water during the rainy season. However, they are extremely sensitive to noises and people, and quickly retreat into their burrows. Even if they hide once, if you wait patiently with your camera in front of the hole, they will come out after a while. As my eyes adjusted, I could see Queen Crabs everywhere. It seems that the population density is higher than I thought. Of course, this place is a protected area and no one takes them, which is probably why this population is maintained. I was quite excited as I was taking pictures, but since it was a wet and dimly lit place, there were quite a lot of mosquitoes. They have to remain motionless to take photos, which makes them good prey for mosquitoes. By the time I returned home, my arms and legs were bruised.

At the time, there seemed to be a movement in the town of Thongpapun to make the queen crab a specialty, and T-shirts with crab illustrations and crab figurines were being sold at various shops in town. Nowadays, it's almost no longer sold, probably because people are tired of it. It seems to be a country that heats up easily and cools down easily.
Several years later, I visited the same habitat during the dry season instead of the rainy season. The obsolete observation path was further damaged by termites and other infestations, and was now hardly visited by people. In addition, the wetlands that used to be wet are now almost dry due to the dry season. Queen crab burrows can be seen here and there, but none of them are out and about like they used to be. Peeking into its many burrows, you can sometimes see a little bit of its legs. After all, time and timing are important when observing living things.

By the way, there are probably some people who would like to keep this beautiful crab as a pet. Unfortunately, however, this Queen Crab is heavily protected by the Thai government. Therefore, breeding is impossible. Those who want to see them have no choice but to make the effort to observe them locally.