Previously in this column, I introduced crabs of the genus Geothesarma from Indonesia. He says that there are two types of crabs of this genus that live in Thailand, where he bases his fieldwork. As a crustacean lover, I would definitely like to see how these Geothesarmas live in nature, so I decided to obtain a paper describing them and try to find their habitat. 
First, I decided to explore the Geosesarma krathing, which I have visited many times to collect and have a good knowledge of. This species lives in a place called Chanthaburi in eastern Thailand. This is the place I came to collect when I first visited Thailand about 20 years ago. During that time, he discovered an undescribed species of betta fish, which led him to become obsessed with fieldwork in Southeast Asia. This betta was later given the scientific name Betta prima. In addition to betta fish, there is also a wetland that is home to an abundance of rare aquatic plants, making it a memorable area that I have visited many times to photograph.

According to the paper, Geothesalma crating lives near a waterfall locally called Khao Katin. The species name, Krating, is derived from this habitat. If you follow the Thai pronunciation, it might be better to call it katin instead of krating.
I visited Khao Katin about a year ago after obtaining information about its habitat. At that time, I did not know where it lived, so I looked for it near the mountain stream upstream of the waterfall, but unfortunately I was unable to find it. Six months later, I searched again, but was unable to find it again. When searching for an organism, once you understand its habitat, it is relatively easy to find it, but I was unable to take that first step.
In October of this year, I stumbled into a bookstore when I visited Thailand and found this article about Geosesalma Krating in a magazine. It's all in Thai, so she can't understand what's written at all. She asked a Thai friend of hers to read it, and it seemed to contain quite useful information. Fortunately, Mr. Non, who was the editor-in-chief of this magazine, is an acquaintance of mine. He was able to call right away and get information about this crab. Based on that information, we will try again. This time, I was given the contact information of a local person who knew this species, so I was able to easily find its habitat. What you should have is a friend.
Their habitat was not a place like a mountain stream with a waterfall, but a place like a wetland in the mountains, where plants such as Alocasia were thick. No matter how hard you search along the mountain stream, you won't be able to find it. I was looking in the wrong place.

When I was guided to its habitat after sunset, I was able to immediately spot this species climbing on the grass. As I was excited about my first encounter and photographing them, I was able to come across this species one after another lying motionless on the waist-high grass. The population was higher than expected. Larger individuals are found in higher places, and smaller individuals are found in slightly lower places. There are also many crabs climbing on the grass. Like other species in the same genus, this species is a small species with an adult carapace width of about 15 mm, and appears to be nimble. Normally nocturnal crabs hate light and will run away if you shine a light on it, but this crab doesn't run away at all. I have photographed many crabs, but this is the first time I have seen one that is so easy to photograph.
After observing them for a while, I realized why they were sitting still on the leaves. Just as a moth flew into the light that I was shining on for the photo shoot, the moths moved quickly and caught the moth and began eating it. When I dropped another small insect in front of it as a test, it moved quickly and caught it. Yes, they were waiting on the leaves for insects to feed on. Its ecology is more like a jumping spider or a praying mantis than a crab.
As I observed them further, I noticed that they were licking the night dew on the grass. They seem to rely on dew on the grass for hydration rather than entering water. I was also able to find a crab that had just shed its skin on the grass. Even red crabs, which are adapted to life on land, go into the water when they molt. This species appears to be completely adapted from living in water to living on land.
When I asked the person who guided me around, I was told that the breeding season for this species is from January to April. At this time of year, Thailand is in the middle of the dry season. It is said that the larvae do not descend to the sea, but instead breed in a large egg, hatching at an advanced stage of development, and it is interesting to know what kind of breeding ecology this species has. We plan to visit again during next year's breeding season to observe them.

Some species of the Geothesarma genus are known to carry their hatchlings on their backs like poison dart frogs. In Malaysia, there is also a species that lives inside Nepenthes.
Crabs of this genus imported from Indonesia as pets must have an interesting ecology locally.
It is very interesting to see how crabs, which originate from the sea, have adapted to life in freshwater and are even transitioning to life on land.
If I have any new knowledge, I would like to introduce it in this column.