Fish is the most ancient vertebrates. They inhabit the Earth almost all aquatic environments ━ ━ from freshwater lakes, rivers to the sea and ocean water. Pisces is the largest extant vertebrate subphylum a key link, from the perspective of animal evolution, the jaw outline is the beginning of class, it is like to have the most primitive jaw, the oldest one outline. This is the largest subphylum vertebrate taxa, far away in the Devonian had derived a lot of the edge of the branch, development and evolution has become a complex shape of the fish. Cartilaginous fish fish into the existing system and the bony fish line. I. Department of cartilaginous fish (chondrichthyes) The existing system is the lowest level of a fish taxa, there are around 200 kinds, China has 140 kinds, the vast majority living in the sea. Its main features are: ① life without the hard bone, bone from the cartilage within the composition. ② surface mostly been Su scales. ③ developed gill spacing, no gill cover. ④ crooked-type tail. The department is divided into two subclasses, namely board PROSOBRANCHIA and full head subclass. II. Bony fish line (osteichthyes) Department of bony fish is the world's remaining fish in the largest group, with more than 20,000 kinds, most live in the sea waters, some live in fresh water. Its main features are: ① bone to varying degrees, as bony sclerosis. ② surface is hard scales, scales or circular comb scales, a few types of degradation and scales. Skin mucus glands developed. ③ degradation of some or all of gill spacing, gill openings not directly in vitro, with bone of the gill cover shielded, water flowing from the gill slits, the posterior edge of gill cover to drain away, the majority of bladder. ④ tail often has a positive-type tail, also the original tail or crooked tail. ⑤ most in vitro fertilization, oviparous, there are a few in the developing metamorphosis. The earliest fish appeared during the Cambrian period 450 million years ago on Earth round the mouth of the fish without jaws. Fish is easy to distinguish from the outside, they formed the largest groups of vertebrates: the total number of 5 million species of vertebrates, fish have 20002 thousand species. Not all the animals living in water are fish. For example: whale is mammal. However, all fish can be well adapted to water life. They use the fin movement. There are two pairs of fin fish ━ ━ pectoral and pelvic fins, which are located the body of the two; and a tail, the growth in the tail; and depending on the different types, in the back gave birth to one or two dorsal fins, a birth in the superior gluteal anal fin. They have a gas-filled sac, called the swim bladder, which allows the fish to the _set_tlement in the water, floating and maintain position. Only the rays and sharks do not have this organ. Fish have gills to breathe, most types of gills gill cover bone coverage. Gills in the head on both sides of the mouth of the rear, used to filter water from the mouth swallowed, get oxygen from the water, then known as the gill slits of the water discharge openings. Different types of fish size vary greatly. Their body consists of three parts: head, trunk and tail. Skin covered with scales, the size and number of different. In a clear line on each side called the lateral line is a sensory organ, used to determine direction. Some bony fish muscle is separated from some small bones. The first appeared on Earth without jaw fish round the mouth, there are only 70 kinds of fish such as the existence, form a non-jaw fish. In these fish, the lamprey is most famous, they do not have scales, slender body round, like the eel. Lamprey through the mouth with a suction cup attached to the other fish, taking the blood of a living host. Other fish are divided into two categories: bony fish and cartilaginous fish. Cartilaginous fish have a skeleton composed entirely of cartilage, reinforced by calcium. These fish are mainly sharks and rays fish heads. Eel is born with a physical flat fish, known as "small eel." Mature when they have a long smooth body, usually without scales, along the back is a continuous fin. Eel living in Europe and the Americas rivers and lakes, they migrate to the North Atlantic sea algae northeast of the West Indies, where the breed. Pups after birth they will die. Small eels in the way back across the Atlantic, showing the adult form, in the way home, they began to birth in the Sargasso sea. Herring live in the North Sea, English Channel and Baltic Sea. Adult fish have a pale belly and a dark blue or nearly black on the back. Like sardines and shad, as they live solitary lives, sometimes thousands of fish live together. For each fish, this is an effective self-defense, because a predator, the only choice in many fish in a target. When attacked, the fish almost immediately disappeared. Thorn in finfish about 60 million years ago. Perch is a typical representative of this type of fish, their fins by the hard, sharp spokes to support the huge tail fin has spines. Perch living in Europe and North America's lakes and rivers, they eat invertebrates and small fish, including their own juveniles. These other types of fish live in the ocean, such as tuna and swordfish, which are strong swimmer, swim 100 kilometers per hour. Can tuna weighing 500 kilograms, is the predator. In fish, they have a unique ability that is higher than the water temperature to maintain body temperature, their species include Pacific albacore tuna in the Mediterranean and Atlantic bluefin tuna. Modern sharks and rays are cartilaginous fish, the main representative of the animals, the cartilaginous fish may appear in 410 million years ago. As their name suggests, they have a skeleton composed of cartilage. Cartilage is a time full of hardened calcium flexible material, is as solid as bone. Cartilaginous fish in the ocean in temperate and hot massive growth. They breathe in the water with gills. Gill by gill slits back of the head of several direct communication with the outside world. Cartilaginous fish, about 550 species, of which 370 kinds of sharks, the other basically flat from the body of skate and skate power components. _Select_ion of fish for biomedical research, particularly drug toxicology and pharmacology studies, has many unique advantages: fish for certain drugs, gas is very sensitive, as long as the composition of very low concentration can cause a strong reaction; to Fish for pharmacological, toxicological testing, divided by the death of indicators, the impact of their habits may be more sensitive; to smaller fish directly into the suitability of different concentrations; this study some of the pharmacological effects of low or weak and requires long-term oral administration of Chinese herbal medicine may be more appropriate; fish for certain central nervous system stimulant or inhibitor of the reaction more sensitive; fish test method results to determine a clear and easy to grasp; in feeding management, fish is a more economical experimental animals. To date, more than 20 generations of inbreeding pure fish animals (gordon's, 1950); sterile fish is also exploring the development of experimental animals in (luckey's, 1936). Fish have been widely used in experimental animal embryology, genetics, endocrinology, toxicology, behavioral science, comparative pathology, environmental science, experimental research (mitruka's, etc., 1976). Some animals fish irreplaceable unique advantages and characteristics of its biological properties can with the corresponding characteristics of the human analogy. In the country, and farming of fish on many subjects, but as the experimental animals to research and development and application is done very lacking (Zhu Xi's, etc., 1960,1962). Goldfish (carassius auratus linnaeus) applications in biomedical research have been reported. To diethylnitrosamine (diethylnitrosamine) to vote in the goldfish bowl in the water (less than 120ppm) lasted 4 months, 6 months and then keep raising found: in 13 experimental group animals, a fish liver liver cancer ; another four fish, the liver precancerous cell lesions (bannsch, 1976). Control animals the liver were negative. Suggesting the possible application of goldfish as an experimental animal model for the establishment of induced tumors. Fish in toxicology has a unique purpose. Fish are often used for acute toxicity, for these experiments, before the test and the experiment must be strictly experimental conditions: in the region must be a representative _select_ion of the test fish, this species is more sensitive to the harmful substances. Food organisms, also must meet the test requirements. During the experiment, try to maintain stable concentrations of harmful substances in the water, and strive to the required concentration can be found in toxicity. For toxicity tests, requiring both freshwater and sea fish or sea fish, for the test, the average length of 50 mm below the best. Just collected the fish, preferably domesticated one week or less, until gradually adapt to the experimental conditions. Domestication process of feeding the amount is less, two days before the experiment to stop feeding. 4 days before the experiment, domesticated fish mortality and morbidity rates have more than 10%. Maintained at a certain temperature range. Warm water fish requires 20 ~ 28 ℃, cold water fish to maintain 12 ~ 18 ℃, the general scope of the changes should not exceed 4 ℃. Each test concentration group put out 10 or more test fish, should be flow-through test device, a continuous replacement of the water tank experiments, changing the water every 6 to 10 times. The use of a hydrostatic-type test methods, the experimental concentration of water per 1 liter of fresh water for 1 g or less; sea water to keep 0.3 g or less, at least every 24 hours all the water needs to be replaced once, the number of applications on the pitch _select_ion 100,75,56, 42,32,24,18,13.5,10 ml / liter test concentration of 5 to 10 levels. I have to carry out exploration test, primary concentration must be included in the 24 to 96 hours, 50% of the mortality levels. Experimental dissolved oxygen content, warm water fish not less than 4 mg / l; cold water fish not less than 5 mg / liter. Test fish died or not, can hit the tail light glass rod shank, such as fish do not move, that is, to determine death. Requires the same time as control experiments, when the fish died in the control group more than 10% or unhealthy fish, the experimental results obtained can not be used. Qishan Rumble Fish (macropolecs opercularis) or Thai fighting fish (betta splendens) is a measure of drug inhibition of instinctive behavior of the sensitive animals. Fighting fish grown in Southeast Asia, China's Guangdong Province have kept supply. Rearing temperature of 27 ~ 29 ℃. When feeding, such as tap water, to be open for 24 hours or more, should avoid the drug into the undiluted, rabbit fish, high concentrations of drugs into drinking poison. Female male gregarious when not fighting. Feeding time as the day after the isolation of mature male encounters another male fighting action occurs. If two males were kept in a square glass tank, the middle two cylinders separated by cardboard, cardboard can be seen removing two gill cover open, softened dorsal fin, tail fin, the impact to each other. Such as chlorpromazine into, the content of 2 mg / l, may terminate the fighting fish fighting action. Such as a drug to inhibit instinctive behavior, then you can not make the two fighting fish fighting erupted. Some drugs inhibit the fish are fighting according to the extent of the role is divided into five phases: 0 to not inhibit the fight; one to tame, curb fighting action, feeding as usual; two of imbalance or sideways; three of anesthesia, sideways touch of mild or disappear; four for death. Catfish (ictalurus nebulous) no power organs, but there are sensitive electric sense have been found four power sensorium, the back line that leaves the medulla, cerebellum posterior lobe, in the semi-circular protrusion of brain nuclei and the former Long. Sensorium suitable for electric dipole field of the stationary and the reaction. Catfish fish length of 15 ~ 20cm, temperature (1 ~ 4 ℃) to anesthesia, and then open a small hole in the top of the head, revealing want to record the brain after surgery intramuscular injection of 0.5mg/kg of tube curare, the sinking catfish tank experiments, only the surgical site above the surface, with a latex tube to contain the water saturated air into the mouth, artificial respiration, using glass microelectrodes (35 ~ 60mΩ) or tungsten microelectrodes (3 ~ 12mΩ) for extracellular recording, record parts of the cerebellum and the former Long rear leaf nuclei.
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Introduction
Fish is the most ancient vertebrates. They inhabit the Earth almost all aquatic environments ━ ━ from freshwater lakes, rivers to the sea and ocean water.
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Classification
No fish is generally divided into two categories jaw and jaw. No spine cylindrical jaw class, life exists, and no lower jaw. Originated in the endoderm of the gill was cystic, also known as Stinging class; brain development, generally with 10 pairs of cranial nerves; a pair of visual devices and hearing device. 1 or 2 inner ear with semicircular canals. The heart, blood red; epidermal cells from the layers. Even fin hypoplasia, and some Paleozoic bone turtle Class of pectoral. No jaw on the classification of different classes, generally be divided into: hagfish Gang, Gang head turtle, lamprey classes, fin turtle Gang. There are classes with upper and lower jaw. Most with pectoral and pelvic fins; developed within the bone, adult spinal cord degenerate, with the spine, with very little bone exoskeleton. Inner ear with three semicircular canals. The formation of gill tissue from the ectoderm. Pisces by the shield skin, cartilage, Pisces, Pisces and spine Osteichthyes composition. Which shields the skin and spine Pisces Pisces only fossil species. Scattered around the world, the main habitat in the low-latitude sea, in freshwater habitats of individual species. Belong to existing species and the entire board PROSOBRANCHIA first subclass. Elasmobranch subclass of about 600 species, about 180 Chinese species, the South China Sea as much. All three subjects the first subclass 6 are about 30 species, about 2 Division 3 China is about five. Osteichthyes have ossified endoskeleton, a suture, often the head membrane bones, the body is bone hard scales or scales. Raw fish is now a major branch of the most lush, fin subclass can be divided into the total, lung fish subclass and subclass Actinopterygii other three subclasses. Actinopterygii subclass is one of the largest groups. Perciformes which most species, except Cypriniformes distributed in freshwater, salmon-shaped head, mostly anadromous fish, the other projects mainly in the ocean. World fishery production in the herring and cod-shaped head shaped purposes highest yield, followed by cod class, both total world fisheries production of close to half of the year. China bony fish offshore than 2,000 freshwater bony fish over 700 kinds.
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Structure and fish life activities
Although fish and other vertebrates is the lowest, but already has bones, muscles and digestive, circulatory, respiratory, excretory, reproductive, nervous and feels like a fairly complete organ systems, can be extremely diverse life activities. In addition to its morphological structure and systems related to the development, but also reflects the adaptability of the water environment. Skin, fish scales and body color of the skin including the epidermis and dermis in two parts. Composed of several layers of living cells from the epidermis, during which the distribution of mucous cells, in order to reduce friction and protect the body. Bead Star is a local product of epidermal cell keratinization, and breeding activities. Venom gland and a small number of fish skin is a derivative of light-emitting device. Scales sub-scales shield, hard scales and bone scales. Cartilaginous fish scales called placoid scales. Hard scales and bone scales usually produced from leather. Bone scales arranged in easy to follow action and Tile fish protection. Many potential home fast swimming and camp life of the fish, scales often degraded or disappeared. The body color of fish is often back deep belly light, which is compatible with the protection of the environment color. But living in the coral reef fish tend to have bright colors and stripes, camouflage and warning color it normally two. Fish with bones and muscles and limbs well-developed axial skeleton, for the protection of central nervous system, sensory organs and visceral, physical drives, and support activities throughout the body play an important role. Axial skeleton from the skull (cranial thoracic skull and pharynx) and the spinal component. Pharynx skull around the front of a group of gastrointestinal bone to support the mouth and gills. Spine by a number of vertebrae. Smooth muscle and cardiac muscle of fish and higher animals is no big difference, but the phenomenon clearly striated muscle section is divided into sections somite muscle and gill muscle. Arranged by section of trunk muscles arched. The feeding habits of fish feeding and digestion is usually divided into four types. Filter feeders, such as silver carp, bighead carp, sardines and other food plankton; herbivorous, with grass carp is a typical; carnivorous, such as 鱤, dog fish, Channa argus, octopus, herring, etc.; omnivorous, such as carp. The digestive organs of fish into the mouth, oropharyngeal cavity, esophagus, bone, intestines, rectum, anus and other parts. Fish food digestion and gastrointestinal contraction in addition to the outside, but also by external temperature, dissolved oxygen, food intake, physical and chemical properties of food and other factors. Circulation, respiration and excretion by the fish in the heart of the general venous sinus, atrial, ventricular, arterial cone form. Blood from the heart through the ventral aorta into the gill area, the gas exchange of blood, leaving the gill tissue throughout the body distinguish between the blood supply to the head. Systemic blood return to the heart through the venous system. Unique to fish gills breathing organs. Gill gill respiratory surface is a small piece, its very large area. Fish, mainly in the renal excretory organ, connected by a number of renal tubular body composition. Metabolic waste liquid filtered through the renal capsule after the Chinese and the renal tubular excretion. Reproduction and development of fish is generally dioecious, usually paired gonads. Cartilage in vivo fertilization of fish generally, the line ovoviviparous, viviparous or oviparous, the majority of bony fish as in vitro fertilization. The eggs produced by fish as sinking or floating, marine fish are floating. Sexual maturity and species of fish, nutrition, water temperature, light, etc. There are a lot, by the gonadotropin regulation. Eggs hatch after a certain time, larvae Stripping out. Fish life is divided into embryonic, larval period, immature and adult fish period. Larval mortality rates among the highest.
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Geographic distribution
The world's remaining fish very widespread, nearly 4,000 meters and 6,000 meters high mountain waters are deep traces, of which marine fish and freshwater fish species in the ratio of 2:1. Geographical distribution of fish affected by many factors, including salinity, temperature, water depth, currents, oxygen, nutrients, light, bottom sediment type, food resources and food chain structure, and history of the sea changes and so on. About 80% of the distribution of marine fish in shallow shelf areas, especially in the Indian Ocean - Pacific tropical and subtropical waters. Isotherms great relationship with the distribution of marine fish. Boreal and sub-arctic waters in the distribution of the main economic fish herring, cod, salmon, flounder and mackerel, etc.; distribution in subtropical waters mainly sardines, , Can, and mackerel; in tropical and subtropical waters such as the distribution of tuna . China coastal area of marine fish fauna can be divided into five partitions: ① the Bohai Sea, Yellow Sea, the North district, mainly in warm temperate fish. ② South Yellow Sea, East China Sea coastal district, dominated by warm water fish. ③ the East China Sea off the coast district, in the Kuroshio flows through the sea, mainly for warm water fish. ④ the South China Sea coast of the mainland district, mainly to warm water fish. ⑤ the South China Sea off the coast district, mostly tropical reef fish, the total number of nearly a thousand species. Pisces is the largest extant vertebrate subphylum a key link, from the perspective of animal evolution, the jaw outline is the beginning of class, it is like to have the most primitive jaw, the oldest one outline. This is the largest subphylum vertebrate taxa, far away in the Devonian had derived a lot of the edge of the branch, development and evolution has become a complex shape of the fish. Cartilaginous fish fish into the existing system and the bony fish line. I. Department of cartilaginous fish (Chondrichthyes) The existing system is the lowest level of a fish taxa, there are around 200 kinds, China has 140 kinds, the vast majority living in the sea. Its main features are: ① life without the hard bone, bone from the cartilage within the composition. ② surface is mostly Dun scales. ③ developed gill spacing, no gill cover. ④ crooked-type tail. The department is divided into two subclasses, namely board PROSOBRANCHIA and full head subclass. II. Department of bony fish (Osteichthyes) Department of bony fish is the world's remaining fish in the largest group, with more than 20,000 kinds, most live in the sea waters, some live in fresh water. Its main features are: ① bone to varying degrees, as bony sclerosis. ② surface is hard scales, scales or circular comb scales, a few types of degradation and scales. Skin mucus glands developed. ③ degradation of some or all of gill spacing, gill openings not directly in vitro, with bone of the gill cover shielded, water flowing from the gill slits, the posterior edge of gill cover to drain away, the majority of bladder. ④ tail often has a positive-type tail, also the original tail or crooked tail. ⑤ most in vitro fertilization, oviparous, there are a few in the developing metamorphosis. The earliest fish appeared during the Cambrian period 450 million years ago on Earth round the mouth of the fish without jaws. Fish is easy to distinguish from the outside, they formed the largest groups of vertebrates: the total number of 5 million species of vertebrates, fish have 20002 thousand species. Not all the animals living in water are fish. For example: whale is mammal. However, all fish can be well adapted to water life. They use the fin movement. There are two pairs of fin fish ━ ━ pectoral and pelvic fins, which are located the body of the two; and a tail, the growth in the tail; and depending on the different types, in the back gave birth to one or two dorsal fins, a birth in the superior gluteal anal fin. They have a gas-filled sac, called the swim bladder, which allows the fish to the _set_tlement in the water, floating and maintain position. Only the rays and sharks do not have this organ. Fish have gills to breathe, most types of gills gill cover bone coverage. Gills in the head on both sides of the mouth of the rear, used to filter water from the mouth swallowed, get oxygen from the water, then known as the gill slits of the water discharge openings. Different types of fish size vary greatly. Their body consists of three parts: head, trunk and tail. Skin covered with scales, the size and number of different. In a clear line on each side called the lateral line is a sensory organ, used to determine direction. Some bony fish muscle is separated from some small bones. The first appeared on Earth without jaw fish round the mouth, there are only 70 kinds of fish such as the existence, form a non-jaw fish. In these fish, the lamprey is most famous, they do not have scales, slender body round, like the eel. Lamprey through the mouth with a suction cup attached to the other fish, taking the blood of a living host. Other fish are divided into two categories: bony fish and cartilaginous fish. Cartilaginous fish have a skeleton composed entirely of cartilage, reinforced by calcium. These fish are mainly sharks and rays fish heads. Eel is born with a physical flat fish, known as "small eel." Mature when they have a long smooth body, usually without scales, along the back is a continuous fin. Eel living in Europe and the Americas rivers and lakes, they migrate to the northeast of the West Indies, the North Atlantic sea algae, where breed. Pups after birth they will die. Small eels in the way back across the Atlantic, showing the adult form, in the way home, they began to birth in the Sargasso sea. Herring live in the North Sea, English Channel and Baltic Sea. Adult fish have a pale belly and a dark blue or nearly black on the back. Like sardines and shad, as they live solitary lives, sometimes thousands of fish live together. For each fish, this is an effective self-defense, because a predator, the only choice in many fish in a target. When attacked, the fish almost immediately disappeared. Thorn in finfish about 60 million years ago. Perch is a typical representative of this type of fish, their fins by the hard, sharp spokes to support the huge tail fin has spines. Perch living in Europe and North America's lakes and rivers, they eat invertebrates and small fish, including their own juveniles. These other types of fish live in the ocean, such as tuna and swordfish, which are strong swimmer, swim 100 kilometers per hour. Can tuna weighing 500 kilograms, is the predator. In fish, they have a unique ability that is higher than the water temperature to maintain body temperature, their species include Pacific albacore tuna in the Mediterranean and Atlantic bluefin tuna. Modern sharks and rays are cartilaginous fish, the main representative of the animals, the cartilaginous fish may appear in 410 million years ago. As their name suggests, they have a skeleton composed of cartilage. Cartilage is a time full of hardened calcium flexible material, is as solid as bone. Cartilaginous fish in the ocean in temperate and hot massive growth. They breathe in the water with gills. Gill by gill slits back of the head of several direct communication with the outside world. Cartilaginous fish, about 550 species, of which 370 kinds of sharks, the other basically flat from the body of skate and skate power components.
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Medical role
_Select_ion of fish for biomedical research, particularly drug toxicology and pharmacology studies, has many unique advantages: fish for certain drugs, gas is very sensitive, as long as the composition of very low concentration can cause a strong reaction; to Fish for pharmacological, toxicological testing, divided by the death of indicators, the impact of their habits may be more sensitive; to smaller fish directly into the suitability of different concentrations; this study some of the pharmacological effects of low or weak and requires long-term oral administration of Chinese herbal medicine may be more appropriate; fish for certain central nervous system stimulant or inhibitor of the reaction more sensitive; fish test method results to determine a clear and easy to grasp; in feeding management, fish is a more economical experimental animals. To date, more than 20 generations of inbreeding pure fish animals (Gordon's, 1950); sterile fish is also exploring the development of experimental animals in (Luckey's, 1936). Fish have been widely used in experimental animal embryology, genetics, endocrinology, toxicology, behavioral science, comparative pathology, environmental science, experimental research (Mitruka's, etc., 1976). Some animals fish irreplaceable unique advantages and characteristics of its biological properties can with the corresponding characteristics of the human analogy. In the country, and farming of fish on many subjects, but as the experimental animals to research and development and application is done very lacking (Zhu Xi's, etc., 1960,1962). Goldfish (Carassius Auratus Linnaeus) in biomedical applications in the study have been reported. To diethylnitrosamine (Diethylnitrosamine) to vote in the goldfish bowl in the water (less than 120ppm) lasted 4 months, 6 months and then keep raising found: in 13 experimental group animals, a fish liver liver cancer ; another four fish, the liver precancerous cell lesions (Bannsch, 1976). Control animals the liver were negative. Suggesting the possible application of goldfish as an experimental animal model for the establishment of induced tumors. Fish in toxicology has a unique purpose. Fish are often used for acute toxicity, for these experiments, before the test and the experiment must be strictly experimental conditions: in the region must be a representative _select_ion of the test fish, this species is more sensitive to the harmful substances. Food organisms, also must meet the test requirements. During the experiment, try to maintain stable concentrations of harmful substances in the water, and strive to the required concentration can be found in toxicity. For toxicity tests, requiring both freshwater and sea fish or sea fish, for the test, the average length of 50 mm below the best. Just collected the fish, preferably domesticated one week or less, until gradually adapt to the experimental conditions. Domestication process of feeding the amount is less, two days before the experiment to stop feeding. 4 days before the experiment, domesticated fish mortality and morbidity rates have more than 10%. Maintained at a certain temperature range. Warm water fish requires 20 ~ 28 ℃, cold water fish to maintain 12 ~ 18 ℃, the general scope of the changes should not exceed 4 ℃. Each test concentration group put out 10 or more test fish, should be flow-through test device, a continuous replacement of the water tank experiments, changing the water every 6 to 10 times. The use of a hydrostatic-type test methods, the experimental concentration of water per 1 liter of fresh water for 1 g or less; sea water to keep 0.3 g or less, at least every 24 hours all the water needs to be replaced once, the number of applications on the pitch _select_ion 100,75,56, 42,32,24,18,13.5,10 ml / liter test concentration of 5 to 10 levels. I have to carry out exploration test, primary concentration must be included in the 24 to 96 hours, 50% of the mortality levels. Experimental dissolved oxygen content, warm water fish not less than 4 mg / l; cold water fish not less than 5 mg / liter. Test fish died or not, can hit the tail light glass rod shank, such as fish do not move, that is, to determine death. Requires the same time as control experiments, when the fish died in the control group more than 10% or unhealthy fish, the experimental results obtained can not be used. Qishan Rumble Fish (Macropolecs Opercularis) or Thai fighting fish (Betta Splendens) is a measure of drug inhibition of instinctive behavior sensitive animals. Fighting fish grown in Southeast Asia, China's Guangdong Province have kept supply. Rearing temperature of 27 ~ 29 ℃. When feeding, such as tap water, to be open for 24 hours or more, should avoid the drug into the undiluted, rabbit fish, high concentrations of drugs into drinking poison. Female male gregarious when not fighting. Feeding time as the day after the isolation of mature male encounters another male fighting action occurs. If two males were kept in a square glass tank, the middle two cylinders separated by cardboard, cardboard can be seen removing two gill cover open, softened dorsal fin, tail fin, the impact to each other. Such as chlorpromazine into, the content of 2 mg / l, may terminate the fighting fish fighting action. Such as a drug to inhibit instinctive behavior, then you can not make the two fighting fish fighting erupted. Some drugs inhibit the fish are fighting according to the extent of the role is divided into five phases: 0 to not inhibit the fight; one to tame, curb fighting action, feeding as usual; two of imbalance or sideways; three of anesthesia, sideways touch of mild or disappear; four for death. Catfish (Ictalurus Nebulous) is not generating organs, but there are sensitive electric sense have been found four power sensorium, the back line that leaves the medulla, cerebellum posterior lobe, in the semi-circular protrusion of brain nuclei and the former Long. Sensorium suitable for electric dipole field of the stationary and the reaction. Catfish fish length of 15 ~ 20cm, temperature (1 ~ 4 ℃) to anesthesia, and then open a small hole in the top of the head, revealing want to record the brain after surgery intramuscular injection of 0.5mg/kg of tube curare, the sinking catfish tank experiments, only the surgical site above the surface, with a latex tube to contain the water saturated air into the mouth, artificial respiration, using glass microelectrodes (35 ~ 60MΩ) or tungsten microelectrodes (3 ~ 12MΩ) for extracellular recording, record parts of the cerebellum and the former Long rear leaf nuclei.
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Physiological characteristics of fish
Pisces main features: - Shape - Sports - Skin and derivatives - Bone - Digestion - Respiratory - Circulation of the blood circulation of fish - Excretion and osmoregulation - Reproductive fish reproductive system - Nervous and sensory - Endocrine 1. Shape (1) spindle Also known as basic, the general shape of fish, swimming in the water for the whole body was spindle and slightly flat. In the three individual axes, the longest axis of the head and tail, dorsal-ventral axis of the second, about the shortest axis, so that the whole side of the body was flat or slightly streamlined to facilitate the movement move forward to reduce the water resistance, so these fish are good at swimming. Often inhabit the water in the upper. Can be used for long-distance migration. Such as carp, grass carp, shark, before fish. (2) side of the flat type These fish in the three individual axes, so the shortest axis, head and tail and dorsal-ventral axis of the axis ratio not too bad, right and left sides to form a symmetrical flat shape, so that the whole body was wide and flat, so the ability to swim more spindle-type poor, living in the water in the lower. Rarely make long-distance migration. Such as pomfret, butterfly fish, bream, mullet, mackerel and so on. (3) flat-type flat three individual axes of these fish in, especially around the long axis, dorsal-ventral axis is very short, so that goes to the next size flat, slow, as the former two types of flexible, multi-battalion benthic life. For example, rays, rays, Angler Kang and catfish, etc. (4) club type Also known as eel-type. Such unusually long tail shaft head, and left axis and the ventral axis is almost equal, very short, so that the whole body was clavate. Their swimming ability than the peace side flat-type flat-type strong. Suitable for underwater cave and the underwater sand soil to live. Such as eel, conger eel and a variety of. In addition, there are some fish as living environment and adapt to the special way of life, while showing a special body, such as the hippocampus, Dragon, sunfish, puffer fish, flounder, fish boxes. No matter what kind of fish size, can be divided into head, trunk and tail of three parts. Characterized by non-neck, head and torso of interconnected fixed and fish and terrestrial vertebrates of the difference between head and trunk of the dividing line is the back edge of gill cover (bony fish) or the last pair of gill split (cartilaginous fish). Trunk and tail generally anus or anal fin trailing edge of the starting point for the line, precisely, is a body cavity or the front end of the caudal vertebrae as a profession. 2. Sports The appendages of fish fins, swimming and exercise to maintain body balance organs. Supported by the fins and fin rays bear bone composed of two types of rays, a horn section, regardless of rays, not branching from the skin occurs, found in cartilaginous fish; the other is the quality of fin scales also known as bone fins, scales derived from the banding section, branch or branches, found in bony fish, rays between the rays associated to thin. Sub-fin spine bone and soft rays of two types, fin spines formed by a deformed fins, is neither a branch nor a section of the spines of fish possess higher. Soft soft section, the distal branch (called branch rays) or branch (called rays unbranched), about two and a half by the merger. Divided into odd and even fin fin fin types. Even for the paired fins fins, including pectoral and pelvic fins and 1 pair, equivalent to the fore and hind limbs of terrestrial vertebrates; odd fins for the unpaired fins, including dorsal fin, tail fin, anal fin (anal fin). Dorsal and anal fin of the basic function is to maintain body balance, to prevent the tilt swing to help swimmers, such as the tail fin rudder, controlling the direction and push the fish forward. Fish generally have the common chest, abdomen, back, buttocks, tail fins and other five. But there are a few exceptions, such as the eel without even fins, fin is also odd degradation; eel no pelvic fins; electric eel is no dorsal fin, and so on. (1) fin Based on the shape and location of the tailbone end of the relationship between the tail fin can be divided into three types. 1) round tail: tail fin of a leaf, tailbone has been back out into the tail fin, the dorsal fin is divided into symmetrical tail end of the tip, common in fish embryos and larvae stage. 2) crooked-shaped tail: tail fin divided into two leaves, the caudal end of the slightly curved upward to the leaves on the caudal fin. On the leaves longer, but slightly lower Ye, forming both inside and outside the upper and lower tail-shaped asymmetrical distortion. Common in modern cartilaginous fish and a few bony fish. Such as sharks, sturgeon, etc.. 3) is shaped tail fin: divided into two symmetrical upper and lower leaves, only the caudal end of caudal fin base, and slightly upturned, retain traces of crooked-shaped caudal fin, caudal fin shape completely symmetrical, the lower lobe of the tail by increasing the bone under the film supports. Fish-shaped tail fin is one of the characteristics of higher. According to the fin-shaped variation, but also includes a variety of fin-shaped. 4) prototype fin: caudal end of the straight stretch to the end of the end of the round, did not like the rounded tail tip, tail up and down the leaves roughly equal, which is a primitive type of tail, found in the round mouth Gang, Pisces found only in juveniles. (2) pectoral Equivalent to the forelimbs of terrestrial animals, was born in the posterior margin of gill cover the chest. To fish with movement, balance and control the direction of motion of the function. When the fish stops moving, the pectoral fins to control the balance of the fish; slowly swimming, paddle also plays the role of pectoral fin; high-speed road, the pectoral fins close to the fish, when it is raised, the deceleration and can be braking; when one side close to the pectoral fins of fish, side of the lift, then lift the side turning towards the fish forward to help from the tail fin rudder effect. (3) ventral (4) dorsal and anal fin Above that carp have a dorsal fin, 3-4 spines and 17-22 soft rays; pectoral fin spines and a 15-16 soft rays; pelvic fins 2 spines and 8-9 soft rays; anal fin 3 spines and 5-6 soft rays; caudal fin 20-22 rays. Perch fin formula D.. Ⅻ an Ⅰ a 13; A.. Ⅲ a 7-8; P.15 a 18; V. Ⅰ-5. Bass said there are two dorsal fins, first dorsal fin composed of 12 spines, no soft; second dorsal fin spines and includes a soft 13; anal fin 3 spines and 7-8 soft rays; pectoral 15 to 18 soft rays; pelvic fins a hard spine and 5 soft rays. Fish movement and changes in body shape and fins have a very close relationship, rely mainly on their swimming power in three ways: ① the use of trunk and tail muscle contraction wave movement. ② rely on the water fins of the swing movement. ③ the use of gill water hole back reaction caused by the fish forward. In addition to the way fish swim outside the movement, a few fish also has a special form of exercise that jump or fly, such as silver carp can be inclined out of the water is high, then vertically into the water. Oblique flying fish jumping out of the water after the force, but also to open large pectoral fins in the air Xiangda about 300m. Salmon can jump across the river in a variety of repeated barrier, migration from the sea to spawn in the upper reaches of rivers. In addition, there are very few fish to reptiles, such as the Angler Kang, bouncing coated. 3. Skin and derivatives Fish from the epidermis and dermis of the skin composed of very thin epidermis, several layers of epithelial cells and the germinal layer, the epidermis rich single-cell mucus glands, the secretion of stick-slip to keep the liquid, the formation of the surface mucus layer, lubrication and protection of fish, such as reducing skin friction; to improve exercise capacity; removal of bacteria attached to the fish and dirt. At the same time, the surface slippery and easy to escape predators. Therefore, the skin of the fish life and survival are of great significance. Epidermis is the dermis, in addition to distribution of wealth within the blood vessels, nerves, skin receptors and connective tissue, the deep dermis and scales there are pigment cells, glorious cells, and fat cells. Pigment cells have black, yellow and red, and yellow pigment cells, melanoma cells exists in the popular fish skin, the red pigment cells, common in tropical exotic fish in the local skin, luster and pigment-containing cells without guano elements of the crystal, there is a strong reflection, so that fish can show a silver-white flash, and some fish living in the dark depths of the ocean or water layer, with the other skin derivatives - emitter glandular cells that secrete rich in phosphorus substances, fluorescent after oxidation in order to trap phototaxis biological, or for the same species and heterosexual contact signals, such as deep-sea snake mullet, fish and angle Angler Kang leading in some species. Between the epidermis and dermis, or dermis, many scales, fish scales are specific to skin derivatives, by the calcium composition, coating the surface of the body or parts of fish (some parts), to protect the fish from the mechanical injury and external negative factors to stimulate, and therefore, "exoskeleton" said. Is one of the main features of fish. Existing fish scales, according to the shape, structure and occurrence, and can be divided into three types. (1) Dun scale joint formed by the dermis and epidermis, dermis, including the evolution of tooth substrate and the board part of that is buried in the dermis of the hard bone of the round or diamond substrate and the tip protruding from the front towards the outside of the body skin, after the central uplift of the cone-shaped spines (tooth). Tooth surface has evolved from the skin covered with enamel, dentin is part of the central canal, the canal opening at the bottom of the substrate, and blood vessels, nerves pass into the cavity. Shark tooth surface of Dun scales and the occurrence of homologous organs and structure should be the same, so the shark's teeth known as leather gear. Dun structure than the original scales, fish scales found in cartilage. (2) hard scales evolved from the dermal bone of the rhombus plate scales, the surface layer of calcified hard scales with a special quality of light, called the flash quality. Hard scales are the most primitive bony fish scales, such as gar and sturgeon scales. (3) bone scales evolved from the dermal bone structure, round, front-end into the scale-hsiang, the back-end exposed outside the skin was free state, each arranged in a tile-shaped complex. According to the shape of the free trailing edge divided into circular scales and comb scales. After a round of free edge of scales smooth blunt, common in the Cypriniformes, herring-shaped head and other lower-level bony fish. Comb scales back edge of the jagged protrusions, common in fish and other senior Perciformes. Whether round or comb scales scales, the surface has concentric ring pattern, said ring. The ring and plant stems, as can be speculated that the fish's age and so, the growth rate and reproductive season and so on. Big fish on both sides of the body has one or several separate nest from the line evolved into a tube, called the lateral line scales, lateral line scales each piece has lateral line, the water can feel low frequency vibrations. Bony fish scales are usually based on their number, size, arrangement of shapes to identify species, record the number of the arrangement of scales commonly used to represent a type fractions, known as scale-type: for example, type of fish scales 28 to 30, said carp lateral line scales of 28-30, lateral line scales of 5-6, lateral line scales of 5-7. 4. Skeleton Fish bone and cartilage by nature two types of hard bone. To maintain cartilage cartilaginous fish life, due to a soft calcareous sediments, known as calcified cartilage. Bony fish bony skeleton mainly, according to different forms and to soften the hard bone and periosteum into two kinds: on the ossification in the cartilage primordium is formed bony softening the hard bone, such as the spine, ear bone, occipital bone, etc.; from the dermis and connective tissue direct the formation of bony ossification of bone called the film, such as the frontal, parietal bone, gill cover bones. Fish bones at different parts, sub-axial skeleton and limb bones of two parts attached. (1) sub-axial skeleton skull and spine 1) the largest number of skull: bony fish skull from the 130 or so bone slices (referring to the existing fish, raw fish, the ancient skull can be up to 180), is the largest number of vertebrate bone in the brain of a class of animals. Fish skull is divided into two parts, the skull and cranial pharynx. ① cartilage is a cartilaginous fish skull protects the brain cavity, simple structure, no boundaries and stitched, leaving only the back of the skull by the membrane covering the brain, the skull so that the soft skull. A soft cartilaginous fish a few pieces of skull bone into the occipital bone, ear bone, sphenoid, ethmoid, and the source of the nasal membrane bone, frontal bone, parietal bone, vomer and other cranial part of the film, which structure is very complex. Bony fish skull bone chip synthesis of many pieces to form the main part of the skull. (2) for the fin attached limb bones Odd fins attached limb bones and even sub-fin skeleton. Odd in the dorsal fin, anal and caudal fins into skeletal muscle by bone in the fin support (Actinopterygii bone) supports rays, bony fish also known as bone support fin fin bear bone. Even fin skeleton, including bone (shoulder and his back) and fin bones (bone and fin rays bear) in two parts. Fish, bony fish, in addition to the shoulder strap is connected with the skull, all of the attached limb bones and spine are not directly linked, which is one of the characteristics of fish, which is due to the movement pattern of fish swimming and decision. 5. Digestion 6. Breathing The ridge push things, only fish and round mouth is the key link with the gills of aquatic life, but the fish's gills are formed by the ectoderm occurs, round mouth like gills originated in the endoderm. Fish generally have five pairs of gill arches (small fish 6 to 7 pairs), in the pharyngeal gill slits on each side 5. Mainly by the gill gill arch, gill septum and gill flap composed of several parts. Gill arch support role, it's the inside edge of the gill rakers of Health, out of the gill blood vessels are passed from the gill arch, gill arch of the lateral edge of the gill septum, the formation of gill gill protruding through the front compartment, numerous closely packed gills by into a comb-like gill flap, gill filaments on the gills of numerous small protrusions called lobular, the gas exchange place. Gills covered with lobular capillary blood within the last into the cavernous, cavernous walls of the connective tissue, supportive, leaf surface for the single gill epithelial cells, it was bright red gills. Bony fish gills than the original, split gill mouth in the body, across the developed gills, before and after each one and a half gills, the general term for the whole two and a half gills gills, gill covers the outside of the protection inside the gill cover gill following cavity or gill chamber, gill hole backwards with a total opening in vitro. Posterior margin of gill cover extensions have soft gill covering film, gill holes can seal tightly. There are four full cartilaginous fish gills, a half gill, nine in half gills, no gill cover. In addition to fish with gills, there are auxiliary breathing organ, such as loach and other use of intestinal gas line swallowed intestinal respiration; mudskipper, catfish, etc. can make the skin breathe; eels and other energy use oral breathing; mullet, catfish, etc. beard can be pleated gills; lung fish with swim bladder breathing. Fish have two nostrils, but the barrier mouth (only lung and total fin fish except two subclasses). Swim bladder is the distinction between embryos from the digest out in the back of the body cavity between the digestive tract and kidney of a membrane bundle, the shape varies according to a variety of fish, there is a room, compartment or room. The main function is to adjust the swim bladder of ups and downs of fish or stay at a certain water level, when bladder volume expansion increases, the proportion of smaller fish in the water, the fish will float when the water level to stay in a certain time, to be released on the swim bladder part of the gas. When the bladder volume decreases, increasing the proportion of fish in the water, the fish sink. From shallow to deep water layer to be stuck in a certain time, you need to sucked into the part of the gas. In short, the gills and the increase or decrease the gas pressure of the water. Bladder volume change is a relatively slow process, so no swim bladder of fish should only live in a relatively fixed water layer. Living in the deep sea, benthic life or camp in the rapids, or travel speed express the fish, swim bladder of their life has lost its role. For example, travel speed quickly sharks, mackerel, tuna, etc. there is no swim bladder. Therefore, they must always maintain a state of motion, only to be stopped in the bottom. Another bladder kinetic energy in gas exchange, and a few bony fish, cartilaginous fish is the swim bladder to help with breathing, such as Africa than fin fish, in the dry season, with 1 on the swim bladder of similar lung gas exchange. Lungfish, gars, also can swim bladder breathing. 7. Circulation of the blood circulation of fish Is a single cycle, the heart mainly by a sinus, an atrium, and as one chamber. Heart pumps the blood circulation plays a role in its contraction the blood (hypoxia blood) pressure Rufu artery diastolic time and the rear from inhaling sinus blood. The blood into the abdominal aorta, below the throat line parallel to the sides of the former branch into the aortic arch, along the beam between the gills to the back of the extension. Separation from the aortic arch into the fold of the blood vessels of the gills into the gill arteries, left gill is a gill artery fold into the gills and the gill to gill arteries capillaries between arteries connected to gas exchange in this conduct. Fresh blood with oxygen through the gill arteries, through the beam on the back of the gill gill import back aorta artery, dorsal aorta and then distributed to the various parts of the body and internal organs, including the head arteries, celiac artery, renal artery and tail artery In these parts of the capillary network in turn enter the former head of the main venous blood, before and after the two merge into mainline total mainline. Another group of internal organs (digestive wall) of the blood capillary network will enter the hepatic portal vein, hepatic portal vein and hepatic artery blood who undergo liver capillaries, and finally import the hepatic vein, hepatic vein and the main vein and the total are into the sinus, and finally flows back to the heart, thus completing the circulation. Bony fish also with arterial ball, can not be beat. Cartilaginous fish with arterial cone, can be automatically rhythmic heart chamber contraction. Artery and arterial cone ball is to make the role of abdominal aortic blood flow evenly to reduce the strong heart beat and gill blood vessels arising from the pressure. Non-hybrid fish blood circulation cycle, moving pulse of blood oxygen content higher than the mixed loop high cycle efficiency. However, the fish heart is very small, only 0.2% of body weight, and mammals in the heart of the 0,59% of total body weight, birds are the heart of the larger, accounting for 0.82% of body weight. So, fish with low blood pressure, blood flow is slow, such as sharks in the abdominal aorta, the average blood pressure of 28mmHg. Thus, the metabolism of fish in the water will lower the. 8. Excretion and osmoregulation Fish excretion of metabolites by the kidney and gills to complete. Urinary organs, kidney, fish kidney is a long purple strips, located in the back of the abdominal cavity, is in the kidney, the excretion of waste, the kidney's main function is to form urine. Dissolved in blood metabolites, such as water and nutrients through the kidney glomerular filtration, in which water and nutrients (such as glucose, amino acids, as well as sodium, calcium, magnesium, chlorine and other ions) to return the blood to most of , the rest of the filtrate and the formation of harmful substances in excess of urine from the ureter out of the body. Other than kidney, gill also nitrides and salt excretion, such as ammonia and urea excretion. Experimental results show that carp and goldfish excrete nitrogenous compounds by the gills is a row of nitrogen compounds kidney 5 to 9 times. Apart from fish kidney urinary function, but also to regulate body water and salt penetration, because fish live in freshwater and seawater in the external environment and the body tissue fluid and blood is usually not isotonic. Sea water salinity up to 3%, and fresh water salt concentration 0.3%, fish live in such an environment, it may cause dehydration, or water. But is not the case, fish can still live life in such water, relies mainly on the regulation of renal handling stolen goods, as well as some special gill cells to compensate and adjust. There are a large number of freshwater fish from the large-scale composition of renal corpuscle and glomerular kidney, when their body fluids and blood concentrations higher than water, the kidneys can continue to discharge the urine (the body too much water), and Meanwhile, the gills of salt absorption in the blood cells, the ED also added salt to keep freshwater fish and salt balance. Marine fish on the contrary, due to blood and body fluids in salt concentrations much lower than seawater concentration, there is a body of water to keep the in vitro penetration trends, to adapt to the environment, marine bony fish drink water a lot to swallow, to be swallowed a lot of salt contained in sea water by the gills of some of the cells secrete salt from the body. Meanwhile, to prevent the body water loss, degradation of marine fish glomerular more or completely disappear. The discharge of urine isotonic with body fluids decrease. Thus, with this in several ways to regulate and maintain the body's salt balance. Some fish from the sea to the middle to Hanoi or to the sea from the middle reaches of the river, can quickly adapt to different salt concentration of the water environment, such as salmon swim from the sea to freshwater rivers irresolute reproductive; eels from freshwater to the ocean to swim to the domain reproduction, these fish Why can quickly adapt to different concentrations of salt water environment. Is how to regulate osmotic pressure? This is a very complex issue, further study. 9. Reproductive fish reproductive system 10. And sensory nerve (1) the nervous system of fish is divided into the central nervous system, nervous system and peripheral systems, including the brain and spinal cord. Fish and other vertebrates, although the brain is divided into five parts obvious, but very small, in general, or more primitive, because some bony fish, not the back of the brain nerve cells, only epithelial tissue. Spinal cord cylindrical, milky white, clear sub-section, each section is an outgoing and incoming nerve, and spinal nerves, sympathetic nervous system and brain play a role in conduction and contact. Peripheral nervous system including brain and spinal nerves. Brain and amphibians, as issued by the brain, a total of 10 pairs, the olfactory nerve, optic, oculomotor, trochlear nerve, trigeminal nerve, the abducens nerve, facial nerve, auditory nerve, glossopharyngeal nerve and vagus nerve, while the other Gang vertebrates have 12 pairs of cranial nerves. On both sides of the spinal nerve is issued by the spinal cord nerves, dorsal root and ventral root in healing from. Dorsal root contains sensory organs or from the dorsal ganglion of the sensory nerve fibers, pass into the spinal cord, it is also called the sensory root. Ventral root contains motor nerve fibers from the bottom of the spinal cord, leading to various parts of the body, known as motor root. Gang of fish and other vertebrates, like, sensory and motor roots in the root pulp at the bow together and become mixed nerve, sensory root and movement than most combined into a spinal nerve root not jaw-free animals more advanced. Fish mixed nerve again divided into three: dorsal branch of the sensory nerves, mainly in the skin, were distributed as part of the muscle motor nerve; ventral motor nerve branch to the main, located in the muscle, but also distributed in the skin to feel nerve; dirty branch is reached sympathetic ganglia, sympathetic nervous system with Unicom. Although fish is the autonomic nervous system sympathetic and parasympathetic, but quite primitive, indicating that fish in the vertebrates is still very low, etc.. (2) sensory organs of sense organs of fish have the sense of smell, sight, hearing, taste and unique aquatic vertebrate lateral line organs. The sense organs of fish and terrestrial vertebrates of the difference is: 1) fish eye sight is weak: in the water to see far away, the lens is spherical, there is no flexibility, flatten the cornea to its notable features. In addition, most of the fish without eyelids and lacrimal gland, so the fish can not open the eye is often closed. Only a few can crawl ashore from the water the fish is limited face, such as the mudskipper and so on. 2) no ear marks of fish body surface, only the inner ear: ear spots in the inner ear (feeling sound) and otoliths (adjusted balance). Bony fish otoliths is usually three, with age and growth, therefore, can this stone to study the age and growth of fish. 3) Fish-specific lateral line: It is a stretch in the longitudinal trunk and tail pipe, it covered the head of the branch form the lateral line organ pipes, this organ can be detectable in the low-frequency vibration, which can determine the direction and size of the wave, perception of the direction of flow and pressure changes, and the surrounding biological activities. Presence or absence of water obstacles, etc. Side of the line by the vagus nerve, a branch of the head innervated by the lateral line. 1) pituitary In the ventral diencephalon, the funnel handle even the third ventricle (between the ventricles) of the bottom. Bony fish from the anterior lobe of the pituitary gland, mesenchymal, and nerve departments of transition leaves, or the first three parts called the main lobe of pituitary, or neurohypophysis nerve Ministry said after the leaves. Anterior lobe of the rear of mesenchymal, the transition between the rear leaf Leaves. Pituitary gland is the most important endocrine glands 1, which secrete various hormones in the body tissue, plays a role in regulating other endocrine glands, such as promoting gonadal hormone, can promote gonadal maturation and spawning, in addition to In addition, brain secretion of pituitary hormones also promote growth and regulate glucose metabolism. Nerves pass from the hypothalamus pituitary primary secretion of pituitary function in vitro. 2) thyroid By the gills of carp cage at the bottom of the thyroid occurred as sporadic small (small sac) dispersed in the throat area of the ventral aorta, gill-based thyroid bone and muscle at the sternum. 3) the body after the gills From the last gill epithelial cells, located between the esophagus and sinuses. Produced after gill physical calcitonin to prevent high levels of calcium, can inhibit osteoclasts of bone tissue disintegration. Summary: the characteristics of the surface covered with fish scales, breathe with gills, living life in the water.
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yulei Fish fish Classification and evolution No fish is generally divided into two major categories of jaw and jaw, and in fish taxonomy is also often the first class of the amphioxus cord Gang (Amphioxi) (see amphioxus) animal classified as a fish-shaped areas of fish within the study. Hagfish Gang (Myxini) no exoskeleton. With a semicircular canal. 10 to 15 gills on each side of the bag, there is a skin tube throat, nose only one, the front opening in the head, and connected within the nose and mouth. Dorsal and ventral spinal nerve roots connected. No fossil record. Hagfish is a group of marine, camp life, fish parasites, there are around 6 genera 32 species, the Pacific, Atlantic, are distributed in the North Atlantic fishery is very strong damage, made in China, 2 and 5 species. Head turtle Gang (Cephalaspides) with two semicircular canal. Many types of bone cells with real bone. Single nostril between the eyes and the top opening in the front of the device. With 6 to 15 gill pouch, gill holes or openings in the head and ventral side. Adult dorsal root of spinal nerve and ventral root is not connected. Appear first in the Silurian Devonian. Lamprey Gang (Petromyzones) fossil found in late Carboniferous. No exoskeleton. With seven pairs of gill sac, nose one in the back of the head, not connected with the mouth. Dorsal and ventral spinal nerve root is not connected. Fresh water, sea water are distributed, is doing the type of semi-parasitic life. Extant lampreys about 30 species, made in China, 3 species found in freshwater rivers in the Northeast. Fin Turtle Gang (Pteraspides) with two semicircular canal. No real bone skeleton, the head disclosed a bone chip. Against the crooked-shaped tail or tail. Cephalic capsule seven gill from a hole opening in the outer gill; paired nostrils, and mouth barrier. Dorsal and ventral spinal nerve roots connected. Three orders, 40 genera, no extant species, are all Paleozoic fish. Mostly small, and the larger can be more than 1 meter. Ordovician of the fins may be originated in the sea turtle, later spread to the brackish and fresh water distribution, Yunnan, China more than gills under the Devonian fish (Polyzanchiaspis) that is similar to the type of fish. No jaw first appeared in the next class of Cambrian fossils, to the Ordovician fossils have been more kind appear. No classes on the systematic relationship between jaw, EA Stein by snow that hagfish and lamprey fins Group evolved from head Group A; but many scholars believe that the most primitive hagfish is no jaw type, and lamprey and the Paleozoic is the first A of the relatively close relationship. A jaw type (Gnatha) with the upper jaw. Most with pectoral and pelvic fins; developed within the bone, adult spinal cord degenerate, with the spine, with very little bone exoskeleton. Inner ear with three semicircular canals. The formation of gill tissue from the ectoderm. The first class has emerged in the jaw Silurian. Shield the skin from the Pisces (Placodermi), cartilage Pisces (Chondrichthyes), spine Pisces (Acanthodii) and Osteichthyes (Osteichthyes), of which only fossil species 1, 3 Gang, 2, 4 Gang is both rich The Paleozoic taxa, there are a large number of extant taxa. Shield skin Pisces head and shoulder were in the Department of membranous bone plate head armor to activities, and a footer between the joints connecting. Notochord exists only by the spinal cord bow, arch and spine composed of veins.
the Atlantic Ocean