Sturgeon is one of the earliest vertebrates in existence. Sturgeon belongs to bony fish, radial fin subclass, chondroscleroderma and sturgeon. We usually say sturgeon refers to sturgeon-shaped fish. It is one of the most primitive schools of fish.
There are 27 species of 1 order, 7 genera and 2 families in the world, which are only distributed in the northern hemisphere. There are nine natural distribution areas, namely, the east coast of the Pacific Ocean, the Great Lakes region of North America, the northwest Atlantic Ocean, the Mississippi River basin and the Gulf of Mexico in North America, the northeast Atlantic Ocean, the Caspian Sea region, Siberia and the Arctic Ocean basin, the Heilongjiang River system and the estuary of the Sea of Japan, the Yangtze River and the Pearl River system. Due to the change of natural environment, the construction of water conservancy facilities and overfishing, the wild sturgeon resources in the world have decreased significantly in recent years and are in an endangered state. There are 8 species of sturgeon distributed in natural waters of China.
Appearance characteristics
Sturgeon is slender and usually spindle-shaped. The cross section of the trunk is approximately pentagonal. Kiss the minister, the body surface is covered with 5 ribs, or sometimes bare. There are no orbital septum, anterior branchial lid and intermbranchial lid. Is there a bone plate on the head? There are 1 rows of spiny scales on the upper edge of caudal fin. Fins don't ossify. Posterior position of dorsal fin and gluteal fin. The pectoral fin is very low. The ventral fin is in front of the dorsal fin. The caudal fin is curved or whiplike, and the upper leaf is longer than the lower leaf. The inner skull is cartilage, only partially ossified. The left and right palatal quadrate bones are not connected with ethmoid bone region or sphenoid bone region, but are fixedly connected with jaw bone. There's a collarbone, no vertebral body. The swim bladder is big, and the dart tube is connected with the back of esophagus. Short esophagus. The stomach is as big as a pyloric cyst. The intestine is short and has a well-developed spiral valve.
Living habits
Sturgeon inhabits the middle and lower water. The migratory species of Haihe River and the settled species of the river move to the upper reaches of the river during spawning period. In winter, it is mostly in rivers or near-shore deep waters. Larvae usually feed on plankton. In the larval stage, benthic aquatic oligochaeta, aquatic insects, small fish, shrimp and molluscs are the main foods. In the adult stage, it feeds on zoobenthos or animal and plant dregs, while the shovel sturgeon still feeds on plankton.
distribution range
They are all distributed in the northern hemisphere, and there are nine natural distribution areas: the east coast of the Pacific Ocean, the Great Lakes region of North America, the northwest Atlantic Ocean, the Mississippi River basin and the Gulf of Mexico in North America, the northeast Atlantic Ocean, the Caspian Sea region, Siberia and the Arctic Ocean basin, Heilongjiang and the Sea of Japan, the Yangtze River and the Pearl River.
There are 7 species of wild sturgeon in China, including ACIPENSER schrenckii, bighead carp and ACIPENSER kuiper, which are distributed in Heilongjiang, Songhua and Wusuli rivers. ACIPENSER sinensis and ACIPENSER davidii distributed in the Yangtze River and Jinsha River basins; Bare-bellied sturgeon distributed in the waters of Yining and other places in Xinjiang; Siberian sturgeon is distributed in Irtysh River, Bulento Sea and Bosten Lake in Xinjiang. Up to now, China has introduced more than a dozen kinds of Russian sturgeon, European herring, small sturgeon and white sturgeon from abroad for research or artificial breeding.
The scientific name of catfish is long snout fish, commonly known as "Jiangtuan", "Baiji", "Fat Head Fish" and "Fish". Taxonomically, it belongs to Siluriformes, Siluridae and Coilia. Dragon-snooker is a rare freshwater fish in China, distributed in the Yangtze River system, reaching the Yellow River in the north and the Minjiang River system in the south. Silver carp is thick and long, with swollen abdomen and flat tail. The individual weight of silver carp varies, generally1500 ~ 2500g.
morphological character
The body length of spiral fish is 4.7-5.9 times of body height, 3.2-3.7 times of head length, 5.2-5.8 times of tail stalk length and 2.5-2.6 times of fore-and-aft length. The head length is 2.2-2.9 times of the length of the kiss, 10.6- 17 times of the eye diameter, 2.4-2.9 times of the eye distance, 1.3- 1.6 times of the head width, and1of the mouth fissure width. The length of the tailstock is 2.3-3 times the height of the tailstock. 33-35 free vertebrae.
The body is slender, the front is thick and short, and the back is flat. The head is slightly larger, the back is convex, and it is not covered by membrane; The superior occipital spine is rough and bare. The kiss is quite sharp and prominent, and it is conical. The mouth is low and curved. Lip hypertrophy. The upper jaw protrudes from the lower jaw. Maxillary, mandibular and palatal bones all have villous teeth, forming an arc-shaped toothed belt. The eyes are small, on the side, the eyes are not free, and they are covered with skin. Eyes are widely spaced and convex. The front and rear nostrils are far apart, and the front nostril is short and tubular, located below the front end of the kiss; The posterior nostril is fissure-shaped. The nose must be located at the front edge of the posterior nostril, and the back end reaches the front edge of the eye; The posterior end of the jaw exceeds the posterior edge of the eye; The chin must be shorter than the lower jaw and the side chin must be longer. Branchial foramen is large. The branchial lid is not connected with the branchial isthmus. Gill harrow is very small. The body is smooth and scaleless.
The dorsal fin is short, the leading edge of the spur is smooth, and the trailing edge is serrated; Its hard thorn is longer than the pectoral fin, and its starting point is perpendicular to the upper part of the posterior end of the pectoral fin, and its distance from the snout is greater than that from the lipid fin. Lipid fin is short, and the base is located behind the base of dorsal fin to the base of caudal fin. The starting point of gluteal fin is located behind the starting point of lipid fin, and the distance from the root of caudal fin is almost equal to the distance from the back end of pectoral fin. Below the pectoral fin, the trailing edge of the hard thorn is serrated. The ventral fin is smaller, and its starting point is vertically below the back end of dorsal fin base, which is farther from the back end of pectoral fin base than from the starting point of gluteal fin. The anus is located at the midpoint from the starting point of the anal fin to the rear end of the base of the pelvic fin. The caudal fin is deeply forked, the upper and lower leaves are the same length, and the end is slightly blunt.
The body is pink, the back is dark gray, and the abdomen is light. There are irregular purple-gray patches on the head side and body side. Fins are grayish yellow.
Living habits
Long snooker is a bottom fish. Often live in the river bend waters with slow water flow, deep water depth and many stones. During the day, they often lurk underwater or in crevices, and go out to look for food at night. It mainly feeds on aquatic insects and its larvae, crustaceans, small mollusks and small fish. Sexually mature in winter, spawning in April-June. The egg is sticky and yellowish, and the fertilized egg is attached to the stone to hatch. It grows faster, generally weighing 2-2.5 kg, and can reach more than 10 kg at most.
economic value
Long snooker is a kind of high-quality edible fish with tender meat and delicious taste.
Long snooker grows faster. It is the largest fish of its kind. The largest individual can reach 15 kg, and the common one is 2-4 kg. It accounts for a large proportion of the catch in the Yangtze River basin, while the middle and lower reaches are obviously more than the upper reaches. Catfish is a large economic fish. Its meat is tender and delicious, rich in fat and without thorns. Protein content 13.7%, fat 4.7%, known as the top grade of freshwater edible fish. The most beautiful thing about this fish is its soft belly. Moreover, its swim bladder is particularly thick, and it is a valuable fish belly after drying. Its adhesive layer is thick, its taste is pure, its color is bright and its manufacturing process is unique. The shape of the dried product and a beautiful natural pattern embedded in the swim bladder take care of the light source. It is similar to the Bijia Mountain standing in Shishou City, hence the name "Gabi Fish Belly" and has the saying that "this stone is unique in the world". It is really a treasure in food.
toxicity
Silver carp's dorsal fin spines and pectoral fin spines have poisonous glands, which are highly toxic to freshwater stickleback. After the fish is stabbed, it will immediately produce severe pain and burning sensation. The wound will be punctured, torn, locally bleeding and swollen, and in some cases it will cause fever. The affected area will be painful and itchy for half an hour to 1 hour. Stabbing accidents often occur when grasping, so be careful.