Japanese Crab Identification?

Japanese Crab Identification?

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I saw a crab walking home from work the other night. We're by a river, but I was probably 500 feet away from the river when I saw this one. I apologize for the image quality, all I had was my terrible Ipad camera and no flash. I have provided the original image and one with brightness and contrast modified to make the crab easier to see. It's about 2.1 inches from leg to leg, I threw a 500 yen coin by the crab as a reference, but cropped it from the image.

I am located directly across from Haneda airport, which is on Tokyo bay. The river is close enough to the ocean that we get tides. I'd say the river level varies by as much as a meter, and there are many many crabs on the exposed riverbed at low tide. But again, this crab was far away, and would have needed to climb a three foot tall vertical wall at the river's edge.

The carapace shows the distinctive lines of Chiromantes dehaani (Kurobenkei-gani in Japanese). This species can be found quite far away from the ocean, commonly in brackish streams and rivers. The size fits your description, the width of the carapace is approximately 3-4 cm, giving the entire body roughly the same size as you observed. These crabs are also most active at night.

I have seen these crabs in sheltered areas slightly inland from the sea. Here is a photo of C. dehaani that I took in Tokyo:

While there is a slight possibility that this is Chiromantes haematocheir (Akategani in Japanese), your photo does not show the distinctive red claws and this species is less common in Tokyo Bay due to development and loss of its natural environment of mudflats. Therefore, I think it is save to identify this as C. dehanni.

The Japanese spider crab is a giant sea creature that lurks in the waters surrounding Japan. Gaming enthusiasts probably recognize this crustacean from the Animal Crossing: New Horizons video game, and bold Japanese foodies might enjoy this crab on their dinner table.

The Japanese spider crab is thought to be the biggest crab in the world, with a leg span of up to 13 feet and an average weight of 40 pounds. It is also likely the crab with the longest lifespan, living to be up to 100 years old. Perhaps even more impressive, the spider crab is one of the oldest living species on Earth, dating back about 100 million years.

Open Mouth Insert Crab… or 7 Better Ways to Eat Them

Every winter you can buy crabs in the fresh fish sections in supermarkets as well as order it at many izakaya, a kind of gastro pub, and specialty seafood restaurants. Crab is a popular ingredient in hot pots and soups, for the delicious soup stock it makes, as well as for making sushi.


The texture of crab sashimi is unbeatable. Snow crab legs make a particularly tasty candidate for sashimi, as they’re served extra fresh. Dip them in soy sauce with a dab of wasabi for a well-rounded flavor. If you’re a bit of a food adventurer or enthusiast by any means, this is a great dish to try.


The crab used in nigiri, the most common form of sushi, is packed with a sweet and savory flavor. It’s often served raw or lightly boiled in salt water to enhance the crab’s natural flavor. The sweet crab meat works together with the tangy flavor of the vinegar in sushi rice work together to make the perfect team. Sometimes you can find sushi served with kanimiso, the offal of the crab, and crab eggs.


Everything seems to taste better when it’s fried, and crab tempura is no exception. Tempura is made with cornstarch rather than wheat flour like with other fried foods, so the flavor is lighter. It tastes great with a splash of amadare (sweet sauce), soy sauce, or a pinch of salt.

Boiled or Steamed

This is probably the simplest and most popular way to eat any kind of crab in Japan. Simply boil it lightly in salt water to bring out the original flavor of the crab, cut it into easy-to-eat sections, and you’ve got yourself a gourmet yet casual meal that everyone is sure to love. You could also go to a restaurant, have them do all the work for you, and get twice the enjoyment.

Shabu Shabu

Seafood shabu shabu (a Japanese hot pot dish) served with crab meat is a very popular dish during the wintertime. The name ‘shabu shabu’ comes from the sound the meat makes when you dip and swish it through the soup broth. It’s the perfect dish for keeping warm in the cold winter months.

Teppo-jiru or Kani-jiru (Crab Leg Miso Soup)

This is a soup made with miso, female king crab legs or other chunks of crab meat, a slice of kelp, and simmered to perfection. It goes perfectly with any seafood dish, especially when paired with the next and final dish on this list. It’s everything delicious about crab in soup form.

Kani-meshi (Shredded Crab Over Rice)

Kani-meshi is the absolute finisher to any crab course cuisine. The rice is cooked together with the crab meat and mixed in to distribute the flavor, then topped with more crab. This is a dish often found in boxed lunches and sold at train stations, called ekiben meals. This can be served as a simple side dish or alone for the real crab lover.

Snow Crab (Rock Crabs)

Snow crabs (rock crabs) are a type of edible Alaskan crab

Snow crabs (Chionoecetes opilio) are also called rock crabs and are a type of Alaskan crab with long legs. This species of crab is also found in the cold seas around Alaska and in the North Atlantic Ocean.

The body of this dark-brown colored crab can grow up to 7” (17 cm) across. This type of crab is usually eaten for its tasty white meat in the legs and claws. Unlike some other kinds of edible crabs, you can easily break open the legs to get to the meat.


The crayfish belong to the family of Astacoidea and Paracoidea and live in fresh water. They are found mostly in streams and rivers with deep flows where they can safely shelter from the predators that haunt them, and it is difficult for them to survive in polluted waters because they cannot find the proper food in them. Their body is more elongated than the rest of the crabs, which differentiates them especially from the smaller species. Its morphology consists of 19 parts grouped in the cephalothorax and the abdomen.

Blue Crayfish

These freshwater crabs live mainly in Australia. They can be found in the lowlands, specifically where there are different concentrations of water, such as dams, streams, wells, swamps, reservoirs. Generally, they prefer the crystal clear waters, although they can also be found in other places, of different temperatures. .

Red Crayfish

This species of crayfish is native to the United States, but has spread to various parts of the world. It is worth mentioning the specific case of Spain where they have displaced species of native crabs from that country. The situation reached a point where the hunting and commercialization of this species was prohibited, leaving the inhabitants of a town called the Isla Mayor without job.

We invite you to read our articles crayfish, to learn more about this species.

Geographic range and appearance

Japanese spider crabs live on the Pacific side of Japan as far south as Taiwan and at chilly depths ranging from 164 feet to as low as 1,640 feet. (They spawn at the shallower end of that spectrum.) They thrive in temperatures of about 50 degrees.

In these waters, their mottled orange-and-white bodies, cream-colored undersides, and spiny, oval carapaces blend in with the rocks on the ocean floor. Those round shells and long legs give Japanese spider crabs an arachnid-like look, hence their common name. These animals also have spines behind and in front of their short eye stalks. Males are larger than females and have larger chelipeds, the legs that hold their claws, though females have wider abdomens to hold their eggs.

Japanese Crab Species 1: Snow Crab/Zuwagani

Snow Crabs, or Zuwagani in Japanese are very popular not only in Japan, but also in Russia, Canada and many other countries.

In Japan, they are also known under the following names: Matsubagani, Echizengani and Yoshigani.
The females are also called Seikogani, Megani or Koubakogani.
They are caught mainly in Autumn and Winter.
Their number have decreased in the Japan seas down to a yearly catch of 5,000 tonnes while 60,000 tonnes are imported from Russia and Canada.

Male and female snow crabs are equally succulent, but the males contain more flesh and are accordingly more expensive.

The “thorns” of a male snow crab are bigger.

The “teeth” of a male snow crab are triangular in a seesaw shape.
The female “teeth” are in a straight line.

The underbelly of a female snow crabis flatish.

When buying a female (10 tmes as cheap) snow crab, choose a specimen with as few eggs as possible. Above speciman just has too many!

A female snow crab should contain plenty of succulent orange egg sacs (the eggs not yet “born”). Otherwise, there is very little reason to buy any!

Crabs can be eaten in many ways, even raw, but my favourites are on sushi!

Male Snow crab leg Sushi Nigiri and Female snow crab Sushi Nigiri and its egg sacs!

Suwagani/Snow Crab legs, when lightly boiled can make for beautiful sushi nigiri.

Cheaper varieties can still make fr some remarkable gunkan sushi combining the boiled white flesh and “miso”/brains!

If the Japanese can get their hands on the whole crab, will simply boil it and eat the meat directly out of the shell with a sweet vinegar dressing.
As for the “miso”/brains they will be served in the shell heated again with a big helping of Japanese sake!


Economic Impacts in Chesapeake Bay

Hemigrapsus sanguineus (Japanese Shore Crab) appears to be limited to man-made rocky intertidal habitat (jetties, bulkheads, etc.) in lower Chesapeake Bay (Ruiz et al., unpublished data). Because of its restricted distribution, it is unlikely to have significant economic impacts in Chespeake Bay.

References- Ruiz et al., unpublished data

Economic Impacts Outside of Chesapeake Bay

In areas north of Chesapeake Bay,Hemigrapsus sanguineus (Japanese Shore Crab) is likely to have greater ecological impacts, because rocky intertidal habitats suitable for this species occur naturally. However, because most major fisheries resources in this region are subtidal, economic impacts are likely to be small.

Ecological Impacts on Chesapeake Native Species

Hemigrapsus sanguineus (Japanese Shore Crab) now occurs locally in jetties and other stone structures in lower Chesapeake Bay, but its abundance and impacts are limited by lack of rocky habitat (Ruiz et al., unpublished data).

In New Jersey, it has been considered a potential competitor with native crabs in the intertidal zone (McDermott 1991) and a potentially important intertidal herbivore and predator in Long Island Sound (Gerard et al. 1999). Detailed field studies of interactions between H. sanguineus and other species are in progress on the Atlantic Coast of North America. In Long Island Sound (CT), competition with native crab species is limited because the natives, primarily Eurypanopeus depressus, have little habitat overlap with H. sanguineus (Lohrer et al. 2000). Predation by high densities of H. sanguineus may have a negative impact on populations of Mytilus edulis (Blue Mussel) (Lohrer and Whitlach 2002a), especially on smaller mussels (Bordeau and O'Connor 2003) and possibly on other shore biota.

References- Bordeau and O'Connor 2003 Gerard et al. 1999 Lohrer and Whitlach 2002 McDermott 1991 Ruiz et al., unpublished data

Ecological Impacts on Other Chesapeake Non-Native Species

Hemigrapsus sanguineus (Japanese Shore Crab) now occurs locally in jetties and other stone structures in lower Chesapeake Bay, but its abundance and impacts are limited by lack of rocky habitat (Ruiz et al., unpublished data). It is a competitor with Carcinus maenas (Green Crab) (Jensen et al. 2002 Lohrer and Whitlach 2002b) which reaches the southern end of its range north of the mouth of Chesapeake Bay (Kingsley 1879 McDermott 1991 Williams 1984). It is also an herbivore, with a preference for the green alga Codium fragile over four native species (Bourdeau and O'Connor 2003). However, the extent to which these species interact, in the Chesapeake Bay region, where all of them are in low abundance, is unclear.

References- Brousseau et al. 2001 Gerard et al. 1999 Kingsley 1879 McDermott 1991 Ruiz et al., unpublished data Williams 1984 Jensen et al. 2002

How the Asian Shore Crab Became an Invasive Species

When ships containing cargo travel long distances, they sometimes use water stored in tanks or cargo holds to make up for lost weight as goods are delivered, providing stability in rough seas and making it easier to maneuver the vessel. This is called ballast water, and it is one of the major pathways for the introduction of invasive species around the world. Researchers believe Asian shore crabs arrived in the United States in the early 1980s, when boats released ballast water carried from the crab's native waters into various capes and inlets in the northern Atlantic coast.

The first documented sighting of the Asian shore crab was in 1988 in Cape May County, New Jersey. The crab's range and population quickly expanded from Maine to North Carolina, and researchers expect its population to continue to expand.

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Watch the video: Facts: The Blue Crab (August 2022).