Scientific name: Trionyx sinensis

Trionyx sinensis, crustacea, reptile, tortoise and turtle.

Common names: turtle, turtle, Yuan Yu, turtle, tuanyu, foot fish and water fish.

English name: Soft-shell turtle

Japanese name: スツホン.

There is no effective subspecies differentiation of Trionyx sinensis, but there is geographical variation. Japanese soft-shelled turtle was once called Japanese soft-shelled turtle. The turtle population in Zhoushan Archipelago is also called T.tuberculatus. Nowadays, these names are often regarded as synonyms of Trionyx sinensis. Mei Lan et al. In this paper, the model specimen of Trionyx sinensis-Leifei mouse was studied, and it was considered that it was an effective species different from Trionyx sinensis. The distribution of this species is different from that of Trionyx sinensis, which is only found in East China. The model origin is Shanghai, but it has not been widely recognized.

Trionyx sinensis is widely distributed in China, and it is produced in all provinces except Xinjiang, Tibet and Qinghai. It is distributed in Vietnam abroad, and it has been introduced to Japan, Timor and Hawaii.

In addition to the soft-shelled turtle, there was once another soft-shelled turtle (T.steindachneri) distributed in China. The main difference between it and soft-shelled turtle is that there is a big lump on both sides of the base of the neck and a row of thick wart particles on the front edge of the carapace. Skirts are very developed and only distributed in Yunnan, Guizhou, Hainan, Guangdong, Guangxi and other provinces. In 199 1 year, Zhou et al. [8] discovered another species of the genus Trionyx, which is more similar to Trionyx sinensis, but smaller than 500g g. There are obvious differences between Trionyx sinensis and Trionyx sinensis in appearance, bones, reproductive habits, serum protein electrophoresis bands and lactate dehydrogenase isoenzymes. In recent years, Tang reported another new species of Trionychus-Trionyx sinensis. This species is distributed in the upper reaches of Xiangjiang River in Guangxi, northeastern Guangxi and some neighboring counties and cities in Hunan. It lives in clear and transparent water with gravel as the substrate. Small soft-shelled turtle is similar in size to soft-shelled turtle, and the warty protuberance on its back is similar to soft-shelled turtle. Its belly is white or yellowish, and it will turn red when caught. Wu Huisheng reported that the red and white soft-shelled turtle was found in Hubei Province, which is a variety of Chinese soft-shelled turtle. Fossils of Trionyx sinensis were found in Pliocene strata of China.

morphological character

The body is flat and oval, with armor on the back and abdomen. The whole body is covered with soft leather skin, and there is no horny shield. The body color is basically the same, and there are no bright spots. The head is thick and the front end is slightly triangular. The snout is a slender tube with a long fleshy snout, which is about the same diameter as the eye. The eyes are small, located at the back and sides of the nostrils. The mouth is toothless, the neck is slender, cylindrical, flexible and sharp. There is no obvious macula or wart on both sides of the neck root and the front edge of the dorsal nail. The carapace is dark green or yellowish brown, surrounded by thick connective tissue, commonly known as "skirt". The upper abdomen is gray-white or yellowish-white, flat and smooth, with seven pieces of callus, which are located on the upper web, the inner web, the tongue web, the lower web and the rapier. The tail is very short. The limbs are flat, and the hind limbs are more developed than the forelimbs. There are five toes in each of the front and rear limbs, and webbed between the toes. There are sharp claws on the inner three toes. All limbs can be retracted into the carapace.

Ecological habit

Trionyx sinensis is a cold-blooded reptile. It lives in rivers, lakes, ponds, reservoirs and other fresh water areas with gentle water flow and rich fish and shrimp. It also often appears in mountains and streams. In quiet, clean and sunny waters, the shore is more active, and sometimes it will go ashore but it will not be too far from the water source. Can crawl and climb on land, can swim freely in the water. Like basking in the sun or enjoying the cool breeze. Folk proverbs describe turtle activities as "coming to the seaside in spring, living in Liu Yin in summer, cooling down in autumn, and getting into the mire in winter". There is a habit of sunbathing in summer. In northern China,/kloc-0 hibernates at the end of 0/0, and begins to look for food in April of the following year. I like to eat fish, shrimp, insects and so on. And I also eat aquatic plants, cereals and other plant bait, especially rotten fish, rotten shrimp and other rotten bait. If there is no bait, I will eat each other. Timid, lurking in the water or mud during the day, and coming out for food at night ("catching turtles in an urn" or "catching turtles in an urn" refers to using this habit of turtles to bury the jar underground by the water, and the jar mouth is flat on the ground to form a trap, and the turtle is caught falling into the jar while crawling for food); Hunger is tolerated, but gluttony and cruelty. Mature at 4-5 years old, mate in water from April to May, lay eggs for 20 days, and lay eggs many times until August; Usually only 4-6 eggs are laid for the first time. A female weighing about 500 grams can lay 24-30 eggs. Female turtles over 5 years old can produce 50- 100 a year; Females can generally lay eggs 3-4 times during the breeding season. Eggs are spherical, milky white, with a diameter of 15-20mm and a weight of 8-9g. After the spawning point is selected, it digs a pit with a depth of 10 cm, lays eggs in it, and then covers it with soil to flatten it, and disguises it without leaving any trace; Oviposition is about 10 at a time. After 40-70 days of incubation, the young soft-shelled turtle breaks out of its shell and the umbilical cord falls off into the water 1-3 days. Eggs and young soft-shelled turtles are often attacked by mosquitoes, mice, snakes and insects. The spawning grounds are generally quiet, dry, sunny and soft in soil. According to research and observation, its height from the water surface can accurately judge the rainfall of that year. The service life can reach more than 60 years.

Be distributed

Trionyx sinensis is widely distributed in most areas except Ningxia, Xinjiang, Qinghai and Tibet, especially in Hunan, Hubei, Jiangxi, Anhui and Jiangsu provinces. In addition, it is also distributed in Japan, South Korea and Vietnam.

economic value

Trionyx sinensis is a precious aquatic animal with high economic value. In China, soft-shelled turtle is usually regarded as the first choice of food and is used as a nourishing food for dietotherapy. The history of eating soft-shelled turtle can be traced back to the Zhou Dynasty or even further. Soft-shelled turtle has delicious meat, rich nutrition and high protein content, especially the skirt is well known for its delicacy. According to the determination, the content of protein in 100 g of sole fish reached 16.5 g. In addition, it is rich in calcium, phosphorus, iron, thiamine, riboflavin, nicotinic acid, vitamin A and other nutrients.

Trionyx sinensis is a precious medicinal material, which contains animal glue, keratin, vitamin D and iodine. Has the effects of nourishing yin, clearing away heat, calming the liver, invigorating kidney, softening hard mass and resolving hard mass. Carapax Trionycis, head, meat, blood, gallbladder, etc. It's all medicine. According to Compendium of Materia Medica, onychomycosis can cure chronic dysentery, fatigue, beriberi and other diseases. Carapax Trionycis is mainly used for bone steaming, fatigue and heat, yin deficiency and wind movement, hepatosplenomegaly and liver cirrhosis. External application of tortoise blood can cure facial paralysis, malnutrition and hot flashes, and mixing wine can cure women's blood deficiency; Turtle eggs can cure chronic diarrhea and dysentery; Turtle bile has the effect of treating hemorrhoids and fistula. The dried glans penis is called "glans penis", which can cure proctoptosis and sores. Chinese patent medicines made from live turtle, turtle shell or turtle shell glue include Erlong ointment, Wuji Whitestorm pill, Huazheng Huisheng pill, stone pot wine, turtle shell decoction pill, etc.

Trionyx sinensis is also an important export aquatic product in China, exported to Japan, Hong Kong and Macao. Export ports: Shandong, Hunan, Guangdong and Tianjin.

artificial insemination

Because soft-shelled turtle has great edible and medicinal value, artificial breeding has been widely carried out all over the country. Artificial propagation and breeding are carried out, and the main breeding methods are mixed culture of fish and turtles, single culture in ponds and industrialized greenhouse culture. In the artificial feeding environment, Trionyx sinensis likes to eat animal bait such as slaughterhouse waste, silkworm chrysalis and insects. You can also eat melons, fruits, vegetable leaves and synthetic hard particle bait. By providing sufficient bait, keeping proper growth temperature to prevent turtles from overwintering, and raising them scientifically and industrially, the reproduction rate and hatching rate of turtles have been greatly improved. After more than one year of growth, the larvae can weigh about 500 grams, which makes the natural resources of turtles well protected and utilized. With the improvement of people's living standards, there is an increasing demand for soft-shelled turtles at home and abroad, and it has become an inevitable trend to speed up the artificial breeding and reproduction of soft-shelled turtles.

Generally, turtle breeding sites are selected near water sources, with fresh and pollution-free water quality, sufficient water and convenient water intake and drainage. The general water source is the surface water of rivers, lakes, reservoirs and ponds. The most ideal water source is both surface water and factory residual hot water or hot spring water with good water quality, so that the water temperature can be adjusted freely. The subsoil is loam or clay, which has good water retention and poor permeability. The subsoil is covered with a mixture of silt and fine sand with a thickness of 15-30 cm, which is beneficial to the habitat and overwintering of Trionyx sinensis. But the sand should be fine but not coarse, otherwise the skin of Trionyx sinensis will be injured and infected. Acid soil or saline-alkali soil is not suitable for building turtle ponds. The turtle pond should be built in a place with good light, quiet environment and sunny lee. In addition, it depends on whether the transportation is convenient and whether the supply of electricity, energy and feed is sufficient.

The growth and development of soft-shelled turtle can generally be divided into three stages: juvenile stage, juvenile stage and adult stage, which have different requirements for the culture environment. According to the weight, the newly hatched soft-shelled turtle is a juvenile soft-shelled turtle; 1 1-50g is a young turtle; 5 1-200g is a kind of soft-shelled turtle; More than 200 grams are adult turtles; 750-1000g is the parent turtle. Because of the different growth rates of Trionyx sinensis and the habit of cannibalizing each other, it is appropriate to raise Trionyx sinensis with different growth stages and specifications in different ponds, and it is necessary to build parent ponds, larval ponds, larval ponds, breeding ponds and adult ponds respectively. A complete turtle farm should not only have the above five kinds of turtle ponds, but also have spawning rooms, reservoirs and isolation ponds for sick turtles. Warehouse, processing room, pump room, power distribution room, etc. The area matching specification ratio of parent turtle pond, juvenile turtle pond, juvenile turtle pond, breeding turtle pond and adult turtle pond in open-air turtle breeding farm should be 4: 1: 2: 4: 5.

Young soft-shelled turtle has high requirements for feed, which requires fine, fine, soft, fresh and tender feed, comprehensive nutrition and good palatability. Usually red worms, shrimps, silkworms, chironomid larvae, etc. You can also feed the young soft-shelled turtle within one month after hatching, and then feed the fly maggots, earthworms, shrimps, minced fish, animal viscera, prawns, mussels, snails, etc. Be fed gradually. Although the feeding requirement of young soft-shelled turtle is not as strict as that of young soft-shelled turtle, it needs a large amount because of its strong feeding ability. In addition to feeding high-protein animal feed, we should also mix the same amount of fresh fish or pig spleen and dirty milk in the feeding department, and add some vegetable leaf juice appropriately. Stir the feed into a block feed with viscosity, elasticity and ductility. Feed the young soft-shelled turtle 2-3 times a day, usually at 8-9 am 1 time and at 2-3 pm 1 time. The daily feeding amount accounts for about 5%- 10% of the turtle's weight, and the feed is placed on a fixed feed table. At the same time, it is necessary to control the water temperature, water quality and water level, prevent diseases and overhaul escape prevention facilities, and record the feeding situation.

Generally, the breeding process of adult soft-shelled turtle begins with stocking100g soft-shelled turtle, and ends when it is raised to more than 500g for sale. This process is mainly completed outdoors, and turtle breeding can be industrialized if conditions permit. Stocking density varies with turtle specifications. It should be noted that soft-shelled turtles should be fed in grades according to their size to avoid biting each other and affecting their growth; When the greenhouse is moved into the open-air pond, the water temperature difference between them should be adjusted to no more than 3℃, otherwise it will easily make the turtle sick. If the weight of Chinese soft-shelled turtle is 100g, 3-5 Chinese soft-shelled turtles are stocked per square meter; The weight is about 200 grams, 2-3 per square meter. The feeding mode, quantity, frequency and species of adult soft-shelled turtle are basically the same as those of young soft-shelled turtle, and the effect of using compound feed in the feeding process is better than using various single feeds. The following formula can be used in the growth period: 30% fish meal (or silkworm pupa powder, blood powder, etc. ), 30% bean dregs, 3% malt, 30% wheat flour, 3% soil flour, and 65,438+0% vegetable oil, bone meal, earthworm meal and 0.65,438+0% vitamins.

Reproductive and developmental biology

Unlike most turtles, the sex of Trionyx sinensis is determined by sex chromosomes and is not affected by incubation temperature. In China, the accessibility of the fourth instar of Trionyx sinensis has matured. Lofts studied the sexual cycle of male Trionyx sinensis in southern China, and found that there were obvious seasonal differences in the functional activities of vas deferens and interstitial tissue. During the reproductive period, the cytoplasm cells increased, and the weight of epididymis decreased by about 48% after sperm was discharged from epididymis. During this period, the weight of testis is light, there is no big change, and sperm is immature. Spermatogenesis began in May, and spermatozoa at different developmental stages appeared in seminiferous epithelium in mid-May. Sperm production continued in June, July and August, and sperm formation was more vigorous in September. 438+ 10/0/6 The seminiferous epithelium is mainly composed of sperm cells and sperm, and a large number of sperm pour into seminiferous tubules. At this time, the testis is the largest and the diameter of epididymal tubules is reduced. It can be considered that there is an opposite relationship between spermatogenesis in seminiferous tubules and hormone production in interstitial tissue. From June 1 1 to February of the following year, sperm entered the epididymis and stopped producing, the weight of testis decreased rapidly, and the seminiferous epithelium only contained spermatogonia and podocytes. Licht reported the similar cycle of epididymis and seminiferous epithelium. Testicular weight reached its maximum in10 ~1month, and decreased rapidly after sperm was released to epididymis in1February. However, Licht is based on the direct measurement of plasma testosterone level, which does not support the view that hormone secretion and spermatogenesis are separated by Lofts. In fact, plasma testosterone is undetectable for most of the year, even in the spring breeding season, and can only be detected when it reaches its peak in June 5438+065438+ 10. After mating, the sperm of Trionyx sinensis can live in the fallopian tube of female Trionyx sinensis for almost half a year.

In female soft-shelled turtle, the diameter of fully mature egg cell is 17 ~ 20 mm, while that of oogonium is only 8 ~10 μ m. The sexual cycle of female soft-shelled turtle can be divided into four periods: oogonium period, initial follicular period, growing follicular period and mature follicular period. Female turtles lay eggs 2-5 times a year, with 8-30 eggs each time. Warm-cultured turtles can also lay eggs in winter. Egg-white spherical, about 20 mm in diameter, up to 24 mm.

Soft-shelled turtles in the Yangtze River basin mate from April to June, and mating is completed underwater or on the surface, which can last for 5 to 30 minutes. The male holds the female's carapace with his forelimbs, and sometimes bites the female's neck, head or limbs. Trionyx sinensis nests about two weeks after mating. Nesting began at the end of May and ended in mid-August. Nesting is done alternately with hind legs, which have developed claws. Digging from one side to the other, sand piles up next to the nest, and the body swings left and right with the movement surface of the legs. The hind legs are very powerful, and sometimes the sand can be thrown more than 3 meters away. The nest is round, the diameter of the nest mouth is about 7 ~ 10cm, and the depth and width are above 10cm. After the eggs are laid, they are piled up in the nest in disorder, and the eggs are laid within 20 minutes. Then the turtle still digs the sand next to the nest with its hind legs until it is filled.

The incubation period depends on the soil temperature, generally about 60 days (23 ~ 83 days). The tolerance range of eggs to temperature is 22 ~ 36℃, and the optimum incubation temperature is about 32.5℃ under the condition of constant temperature incubation. Compared with natural incubation in the field, incubation at 28℃ can shorten the incubation period 10 day. The embryonic development process of China can be divided into 30 stages. The carapace of juvenile soft-shelled turtle is about 27mm long, 25mm wide and weighs 3-5g. The carapace is dark green with some small black spots.

In addition, the chromosome of Trionyx sinensis consists of 66 chromosomes, 16 large chromosomes (8 centromeres, 2 subcentromeres, 4 apical centromeres and 2 proximal centromeres) and 50 small chromosomes. In addition, the seasonal changes of LDH isoenzymes and blood sex hormones in different tissues of Trionyx sinensis and their relationship with gonadal development were also reported.

Wang Zhan: Trionyx sinensis is an ancient secondary aquatic reptile, which occupies a unique position in the animal kingdom and has important research value. In the study of biological theory, at present, most of the research focuses on morphology, flora classification, ecology, reproduction and development, and few studies on other disciplines.

In morphological research, ultrastructure and its combination with physiology and ecology are helpful to reveal the mechanism of many life phenomena. It is urgent to study individual ecology and population ecology in production practice, especially hibernation and population behavior, which has obvious theoretical and practical significance. The influence and regulation of ecological factors and endocrine on reproduction is also an important research topic.

With the development of turtle breeding industry to industrialization, biochemistry, nutrition and related disciplines will make great achievements in developing deep-processed turtle products. Genetic breeding, feed problems and disease prevention are still the main research directions of Trionyx sinensis breeding industry.