The hairy crab waits two years for its once-in-a-lifetime mating opportunity, and then…

Maple leaves turn red, osmanthus fragrance wafts in the air, every time this season comes, a kind of domineering crustacean will become a delicious delicacy that people will scramble to chase. The north wind gradually rises, the river crabs are getting fat, and the velvety claws and a touch of orange-red bring a touch of warmth to this cold season. There are few foods in the world that people will savor so solemnly. First break the crab legs, then open the crab shell, suck the roe, slowly peel out the crab meat , and then mix it with ginger vinegar. The long-lasting aftertaste is as if you have swallowed the entire golden autumn in one gulp...

The Chinese mitten crab, which has long been famous in the food world, is commonly known as the hairy crab, river crab, and Shanghai hairy crab. It is the only edible crab among the four freshwater crabs in the genus Mitten Crab of the family Crabidae. In its natural state, it is widely distributed in rivers, lakes and reservoirs along the coast of my country, from the Yalu River in Liaoning in the north to the Jiulong River in Fujian in the south. In areas suitable for its growth, the hairy crab farming industry is also extremely prosperous.

What are the intoxicating crab roe and crab paste?

The mitten crab has a nearly circular cephalothorax, with a dark green back and a grayish-white abdomen. Its most notable feature is its pair of claws covered with dense brown hair inside and outside, hence its name. In addition to this pair of claws used for feeding and fighting, the other four pairs of legs covered with bristles are important crawling organs.

Like all crabs, the Chinese hairy crab belongs to the Oviparous suborder of the Decapoda order. As the name suggests, their female individuals will stick fertilized eggs under their abdomen until they hatch. Chinese hairy crabs have tails when they are young, but their tails gradually disappear as they grow, and eventually become pieces of plastron on the abdomen, which is what we often call the " crab navel ."

The navels of male and female crabs | "Chinese Hairy Crab" / Hansheng Culture

The navel of male crabs is long and narrow, called a pointed navel , which is easy to open; the navel of female crabs is round and wide, called a round navel , which is good for protecting eggs. There are abdominal limbs under the navel of crabs. Female crabs have four pairs of abdominal limbs, accompanied by bristles , which are used to attach crab eggs; the abdominal limbs of male crabs are specialized into a pair of powerful copulatory organs , whose only mission is to pass on the family line.

Common mating postures of crabs. The picture shows a Dungeness crab. You can imagine a hairy crab. | reefseekers.com

"Big and heavy as gold, fat and fragrant as white jade", as the leader of the food world, the hairy crab can bring the highest level of pleasure to humans with its rich, sweet and sticky crab roe and crab paste. In comparison, the crab meat has become a supporting role. As a primary species, the life trajectory of crabs is simplified to only development and reproduction. The fat that can make diners so crazy must have been the result of all their efforts and essence.

The "crab roe" of female crabs includes its hepatopancreas and ovaries . After the hairy crab is cooked, the hepatopancreas is usually orange and pulpy, and the ovaries are orange-red paste-like. It has a slightly granular texture when you taste it carefully, and is delicious and mellow. The "crab roe" of male crabs is its accessory glands and their secretions . The mature accessory glands occupy most of the reproductive system and look like a pair of chrysanthemums. After cooking, it is translucent jelly-like, sticky in the mouth, with a distinct sweet aftertaste. Of course, male crabs also have hepatopancreas, so male crabs also have that kind of pulpy crab roe.

High-quality male and female crab roe and crab paste distribution map | flickr.com

Ninety percent of the fat in an adult hairy crab is concentrated in the hepatopancreas . As the main organ for storing energy, the rich saturated and unsaturated fatty acids and a large amount of free amino acids give it a fresh, rich, delicate and smooth taste. The size and texture of the hepatopancreas reflects the fattening degree of the hairy crab and also directly affects the quality of the fat.

Full of yellow pulp | weshare.hk

Before the hairy crab reaches sexual maturity, the gonads are not obvious. The " June Yellow " hairy crabs on the market in summer are hairy crabs that have not reached sexual maturity and have not completed their reproductive molt . The June Yellow, which is about to start its final reproductive molt, is commonly known as "bivalve yellow". The excellent June Yellow roe comes from the hepatopancreas before the gonads develop, but they do not have lumpy crab roe and crab paste.

June yellow can also be beautiful | Chenglongxing official website

Every September and October, hairy crabs tend to be sexually mature, the hepatopancreas gradually shrinks, and the accumulated nutrients begin to transfer to the gonads. The ovaries of female crabs expand rapidly, and the accessory gonads and vas deferens of male crabs also develop, but the transformation speed is slightly slower than that of female crabs. When the hepatopancreas and gonads are similar in size, the freshness and sweetness of the hairy crab fat reach a certain balance. The male's fat is white like jade, and the female's fat is yellow like gold. This is the best time to taste hairy crabs.

Diagram of the internal organs of a female crab | "Chinese hairy crab" / Hansheng Culture

"Round navel in September, pointed in October, hold claws and drink wine under chrysanthemum sky" means that female crabs are fattest in September and male crabs are most beautiful in October . "Frost falls on lake fields in October, pointed navel is better than round navel" also describes the fact that male crabs develop gonads relatively late . In the early spring of the next year, hairy crabs are fully sexually mature , gonads fill the entire chest cavity, liver and pancreas have shrunk, and the roe has lost its freshness, especially in female crabs, the roe is sandy and tasteless, and the crab season is over .

Whether the crab meat is full and whether the roe is rich are important indicators for considering the quality of hairy crabs. If both are taken into account, it is a high-quality hairy crab. The sweetness and viscosity of the crab roe are higher standards for evaluating hairy crabs. The roe of high-quality male crabs has a distinct sweetness and a sticky taste. The taste is more delicate and pure than the crab roe of sea crabs. The sweetness of the crab foot meat is even better than that of sea crabs, which is rare in freshwater aquatic products. This is probably why it is so popular among diners.

In this short life, my heart is towards the distant sea

Chinese hairy crabs spend most of their lives in fresh water, but they eventually yearn for the sea , where their lives began. In late autumn every year, adult crabs in natural water systems migrate downstream, reaching sexual maturity under the stimulation of salt water near tidal river mouths . Under the bright moon and among the blue waves, the mating male crabs come to the end of their lives, while the female crabs swim to deep water with their new lives.

The initial development of seedlings | miaolicrabs.org.tw

In early spring, female crabs with eggs lay eggs in salt water. The crab eggs hatch into two-millimeter-long zoanthid larvae , which drift with the current. Around the end of April, after five molts, the zoanthid larvae develop into large-eyed larvae about five millimeters long. They are spider-like in shape, have a small tail, and have certain swimming and climbing abilities. They feed on plankton and migrate upstream from brackish water to fresh water for food, following the path their parents took.

Hairy crab larvae | miaolicrabs.org.tw

In May and June, the megalopa larvae undergo the last molt and become translucent crablets . At this time, the megalopa larvae's tail disappears, and after another molt, they become juvenile crabs . The entire juvenile crab stage will last until September and October. As the juvenile crabs grow up, their common names also change, such as bean crabs, button crabs , etc., until April and May of the following year . After more than ten molts in a year, the juvenile crabs grow into young yellow crabs . In September and October, the hairy crabs are close to sexual maturity after the reproductive molt. They have gone through a two-year life cycle from hatching to sexual maturity. In the natural environment, hairy crabs will experience two major migrations in their lifetime: foraging and reproduction .

As the crabs grow bigger, the time interval between molting becomes longer, and the weight increases significantly after molting. The hairy crabs need to molt about 22-24 times in their lifetime . Farmed hairy crabs will not have the opportunity to look up at the stars and the sea in the distance. Their fast-forward life is just about eating and growing rapidly, accumulating strength for two years, and looking forward to the only mating in their lifetime. However,...

Although there are many ways to cook crabs since ancient times, most of them emphasize lightness and respect for the natural color. The only way to eat crabs without losing their original flavor is to steam them whole in a steamer without adding salt or vinegar. In the writings of Li Yu, a famous writer in the early Qing Dynasty, river crabs are almost the most delicious in the world: "The best things in the world are solitary. Crabs are fresh and fat, sweet and greasy, white like jade and yellow like gold. They have achieved the ultimate in color, fragrance and taste, and nothing else can surpass them."

High-quality hairy crabs come purely from craftsmanship

Since the 1970s, China's Chongming Island and other places have successfully used natural seawater or artificial seawater to artificially breed hairy crabs. Nowadays, most farmers in various production areas purchase one-year-old crabs or adult crabs for artificial stocking and fattening. The sexual maturity cycle of wild hairy crabs is usually longer than that of farmed individuals . Although some of them may be larger in size, their quality is very unstable due to the pressure of survival and the shortage of bait. Generally speaking, they are not as good as artificially farmed hairy crabs .

Chinese mitten crab invades Europe | mopo24.de

At the beginning of the last century, hairy crabs invaded Europe with the ballast water of trade cargo ships. In just a few decades, they had spread throughout European waterways such as the Thames and the Rhine, multiplying rapidly and causing disasters. At that time, China's native hairy crab natural resources had been severely shrunk due to large-scale water conservancy projects and excessive fishing. In the late 1990s, some institutions tried to introduce wild German Rhine hairy crabs, but ultimately failed because of their low edible value .

Natural factors that affect the quality of hairy crabs include climate and water conditions. When the water temperature is too low, the hairy crabs are firm but small in size; in hot and hot water systems, the growth rate is fast but it is not conducive to the accumulation of crab meat. In overly clear water, there is a lack of animal and plant bait, and the muddy bottom of the water will affect the flavor of the crab meat. Overall, the low temperature in autumn and winter and the gravel waters rich in aquatic plants and animals are most suitable for the growth and fattening of hairy crabs . It is no surprise that Yangcheng Lake and Gucheng Lake have become famous production areas of hairy crabs.

Compared with natural factors, the feeding level is the determining factor of the quality of hairy crabs . Protein and lipids play an important role in the growth and reproduction of crabs. The phospholipid content in the bait has an important influence on the development of crab gonads. Therefore, in the later stage of breeding, hairy crabs need to consume a large amount of animal protein such as fish and shrimp to produce amazing yellow roe . All of this in itself seems so luxurious.

The seasonal hairy crabs are about to appear. The autumn wind blows and the crab legs are itching. It is the perfect time to eat crab roe in the golden autumn. The deliciousness is always worth the effort and wait.

Author: Fish of Salzburg

This article comes from the Species Calendar, welcome to forward

If you need to reprint, please contact [email protected]