Benkeigani: Chiromanates dehani

by K. Saito

Introduction

Chiromanates dehaani is one kind of crab in fresh water. They are called “KURO BENKEIGANI” in japan.They live in almost every prefecture excluding Okinawa and Hokkaido. in Kochi, they live in Shimanto river. They are known creature of river cleaner.
They are nocturnal creature living in dark area,like a cave.So they are hided their body in howl in morning. And they are omnivorous that eat small fish, carcasses, and rotten leaves.

Description & Taxonomy

Chiramanates dehaani’s taxonomy is Arthropoda, malacostraca, Decapoda, sesarmidae, sesarmops.

It is just about 35mm. It size like a thumb. The shell is rugged, it looks like ”Musashibo Benkei” from which their Japanese name “Benkei gani” is derived. (By the way, ”Musashibo Benkei” was warrior in the Heian period, 794 to 1185.) Chiramanates dehani`s shell looks his angry face.

Their color is almost black except for claws which are white. It can hunt under cover of darkness hidden from both enemies and prey alike.

Range & Ecology

Chiramanates dehani live in waterside,riverside and shore between Oga peninsula and Boso peninsula in Japan.It shows they can stand salty water.There are many small fishes leaves and carcasses.

They live in ocean in their childhood. it look plankton. It called “zoea larva”. Zoea larva grow up in a shoal and become club’s look, they come to a river and copulate. After copulation, female Chiramanates dehani come to a seashore and spawn. This is the life cycle of Chiramanates dehani.

Use & Conservation

Chiramanates dehani is not eaten by man. It because Chiramanates dehani is not good taste and have smelling of earth.They are not eaten,but they are bred like crawfish. Almost time they bred is man catching them, but sometimes they are sold in pet shop.In online pet shop, they are sold 3000yen by pair.

On the other hand, they are decided general protection creature in Chiba prefecture.It shows they are decreasing in Kanto area. this is because waterside in Kanto become dirty place and introduced species increased.Even Chiramanates dehani is one of the example of be suffering from destroyed.We have to know that and make an effort to save waterside clean.

Viewing

Chiramanates dehani is index of fertile river. If you want to see them in kochi, go to Shimannto river and thrust a branch into hole. Then, you get many interesting creature, and you can see the crabs that have Benkei’s face.