What are amphibians (amphibian) Amphibians (amphibian) The first air-breathing terrestrial vertebrates, can be inferred from the fossil?? Who appear more than 300 million 60 million years ago the late Devonian. Evolved directly from the fish, appeared on behalf of these animals from aquatic to terrestrial transition. Amphibians have gills early life, when growth is evolved when the adult lung. Amphibians "amphibian" comes from Greek and Zi "two amphi" and "life bios". This is because the amphibians can live both on land and water. Amphibians are also known as an animal, is the history of vertebrate evolution from the aquatic to terrestrial transition type, the adult can be adapted to terrestrial life, but the breeding and larval development also can not do without water. The main features are: body temperature is not constant; oviparous, the larvae live in water, the body can adapt after metamorphosis into terrestrial life, breathing with lungs, skin, naked and wet, no scales, hair and other skin derivatives, rich in mucous glands, with assisted respiration function. Amphibian origins dating back about $ years ago in the Devonian. In the long process of evolution, the fish gradually from water to land and self-improvement to a qualitative change to adapt to the new environment on land, which formed the amphibians, they are the earliest four-legged land animals. As the land between the environment and water oxygen content, temperature change, buoyancy and other aspects of the great differences in the performance of amphibians in many ways not only to adapt to live on land but also to adapt to aquatic life, mainly as follows: Thin skin, a large number of mucus glands to keep the surface moist, but there was a slight skin keratinization. This makes amphibians live in water, can also adapt to a certain extent, wet terrestrial environment, prevent loss of body water. Exist lungs breathing, gills, skin and respiratory (skin and internal distribution of a large number of inter-organizational space and subcutaneous lymphatic vessels) and other breathing patterns. Larvae mainly gills, mainly in adult lung breathing. Heart Center appeared in separate rooms, but more oxygen in the blood blood blood and oxygen can not be completely separated from the blood circulation is not fully two-cycle, low metabolic rate, body temperature changes with the environment. Initially differentiate into cervical spine, trunk vertebrae, sacrum, chase four parts, and evolved the typical toe (finger)-type limbs. These are conducive to movement on land. Nervous system development is still at a low level, with the adaptation of various sensory organs of terrestrial, but larvae still retain the structure and function similar to the lateral line and the fish, and even retain some species to the adult. Excretory organs of terrestrial adaptation is not perfect, for a lot into the body of water, the kidney glomerulus has a strong urinary function, excess water can be discharged. But on land, then the tubular reabsorption of water is not strong so we can not leave the water for a long time. Development of fertilized eggs when breeding in the water must be carried out round robin hatch, no limbs, and fish with gills and other structures similar to larvae (tadpoles), and after metamorphosis (metamorphosis), was not completely into the two-cycle, with limbs, mainly used to gradually adapt to the land of lung breathing adult stage of life.
Translated by Google
Species
Wide variety of amphibians Extant amphibians worldwide total of about 4300 kinds. Divided into three forms according to their head. Caecilians head (no full mesh). Main features are: body slender; no limbs; short tail or no; shape of worms. China only one species, Banna fish salamander. Purpose is the sole representative of China's caecilians. Caudata. Main features are: body cylindrical; the limbs, short; life have long-tail and side flat; reptiles, most species with aquatic life-based, the shape of lizards, such as the giant salamander, commonly known as "salamander", is the largest extant body amphibians. Anura. Main features are: wide body short; the limbs, long; larvae with tail, adult tailless, jumping-type activities, the larvae of tadpoles, from tadpole to adult subject in the development of abnormal processes, such as frogs and toads. Body purpose amphibian three different, their defense, proliferation, migration, weak, dependent on the environment large, although there are a variety of ecological adaptation, but the key link than any other vertebrate species is still small, its distribution in addition to marine and the desert, the plains, hills, mountains and plateaus, and other habitats have traces of them, the highest distribution of up to 5,000 meters above sea level. They are mostly nocturnal, hidden during the day, activities between dusk to dawn, when hot or cold to spend the summer sting or hibernation mode. To animal-based foods, there is no defensive ability of predators, fish, snakes, birds, animals are their natural enemies. Because China is the diversity of biological environments. Existing 302 kinds of amphibians. The Yunnan Because of its geographic diversity and complexity of the natural environment, with a very rich amphibian species, 100 species. Amphibian species accounting for 40% of the number. In the back of animal diversity - Amphibians describes only several representative species. People by recognizing the diversity of amphibian species. Concerned about their living condition, to further protect the friend of mankind
Translated by Google
Feature
两栖类 特点
Amphibians to adapt to the terrestrial environment of the initial 1 exposed but slightly horny skin Thin skin, formed by the layers of cells composed of epidermis and dermis. Exposed skin surface in the state, and the phenomenon has emerged molt; Leather thick and dense, showing the characteristics of terrestrial animal leather; Epidermal cells derived from a large number of multi-gland (mucus gland, venom) and pigment cells (melanocytes, iris cells and yellow cells); ________ Skin and subcutaneous muscle tissue loose connection, during which a large number of lymphatic clearance and distribution of subcutaneous blood vessels, skin and respiratory function with the (Figure). 2. Imperfect lungs breathing and the appearance of incomplete double circulation (1) diversification of breathing With one pair of lungs breathing is also very simple cystic structure of the lung (an important feature of terrestrial vertebrates) in lung wall is rich in blood vessels, the pulmonary artery to the heart of the oxygen blood back into the lungs, by the exchange after pulmonary vein The more oxygen the lungs return to the left ventricle sends the blood. In the absence of the thorax, the respiratory movements by means of lifting the bottom of the oropharyngeal cavity, the air pressure into the lungs to complete the breathing movements (pharyngeal breathing) with pulmonary respiration is compatible The emergence within the nostrils. vocal cords in front of the lung, throat chamber in a short (one of the characteristics of terrestrial vertebrates). Breathe skin moist skin, the skin rich in blood vessels, especially in the winter hibernation period of sleep, skin, breathing life to continue to play an important role. Gills and breathe into the body and all the larvae of the respiratory organs. (2) incomplete double circulation (due to the emergence of pulmonary respiration, circulatory system corresponding significant changes occur, incomplete double circulation and arterial blood is mixed in with the characteristics of amphibians) Heart by two atria, one ventricle, sinus and arterial cone form (Figure). Atrium had complete or incomplete septum formation of the left atrium (receiving from the pulmonary veins return to multi-oxygen blood) and right atrium (from the venous return of the missing venous return of blood and oxygen to the skin than the blood oxygen). trabecular ventricular wall with muscle, and the cone of the spiral and arterial blood to shunt valve can, but do not separate the ventricle, blood and more oxygen the blood and oxygen can not be completely separated This cycle is not complete. Cycle route from single loop circulatory system is not fully evolved into a dual circulation (ie circulation and pulmonary circulation), mainly arterial system Including the carotid artery, arterial and pulmonary artery skin. The difference between the venous system and the larger fish by a large vein and the former after a large vein formed to collect the body of blood back to the right atrium. There are well-developed portal vein and the renal portal vein (Figure). 3 support and movement system has basically met the terrestrial animal model (1) the skeletal system (Figure) Spine with greater differentiation, for the first time a cervical spine and sacrum (with cervical spine and sacrum are the characteristics of terrestrial animals), so that the whole spine is divided into cervical, trunk vertebrae, the sacral and caudal (healing the formation of rod-like The tail rod bone) 4 parts. occipital condyles of the skull and cervical spine (1 pair) relevant section, so head up and down movement with the possibility; sacral iliac connection with the belt, which won the hind legs Solid support. The first time, the sternum, but no adult rib. Apart from a few vertebrae of the vertebral body to double concave aquatic species, but mostly before or after the concave concave. Arch of front and rear with front and rear facet, which is characteristic of four-legged animals. Skull has a shoulder strap from the shackles of several pieces of bone chip is lost or healing, a lower degree of ossification (especially Anura). Maxillary arch and the skull is from the access connection (square jaw and skull cartilage directly connected) . A typical five fingers (toes)-type limbs appear. Limbs at the trunk side, the bones have healed more than the phenomenon by black beak bone, scapula, on the black beak bone, collarbone and skull are not composed of straps Healing, so that the forelimb of diversity has been possible; from the ilium, ischium, pubis and the femoral component in the formation of the hip belt, and with the relevant section of the sacral spine to support body weight. Muscle Some muscle to preserve the original sub-section phenomenon. No Isopoda and Caudata trunk muscle section noticeably, Anura axis only retained under sub-section of the rectus muscle. Axis ratio of muscle to change. Axis muscle ratio decreased, the proportion increased under the muscle axis, and no differentiation of three layers, namely the external oblique, abdominal oblique, transverse abdominal muscle, in order to protect and support internal organs. With limb muscles, and become powerful and complex. Gill muscle degradation. Department of gill muscle control less chewing, tongue and larynx movement. 4 fish complicated than the differentiation of the digestive system Complete digestive system with the structure (oral, oropharyngeal cavity, esophagus, duodenum, ileum, large intestine, cloaca, cloaca hole, digestive gland). Similar to the teeth and fish, for the same type, more teeth may appear in the upper and lower jaws and vomer, etc., without chewing function. The emergence of dynamic muscle quality tongue and mouth glands (a common feature of tetrapods). Independent of the liver and pancreas. 5 with the fish still in the nervous system similar to the lower level (Figure) Part 5 of differentiation of the brain is not high, is still in the same plane, but the nerve to the brain at the top of the material began to shift, that of the original cerebral cortex appear. In the brain is still the highest central nervous system. Already have developed a complete autonomic nervous system. Spinal cord and the fish was no significant difference, but there are shortening trend. Shoulder and lumbar spinal nerve into the plexus concentration. 6. There is a greater evolution of sensory organs Hearing: In addition to the inner ear, the emergence of the middle ear. Inner ear structures and fish are similar, but a true sense of the sound parts of the bottle-shaped capsule (Figure). Vision: corneal bulge, slightly flattened crystals, crystal far away from the cornea, for hyperopia with the lacrimal gland, the lower lid can be active in order to humid eye. Sense of smell: the emergence of terrestrial tetrapods class features two specializations: in the nose (smell and air access routes) and hoe nasal (nasal ventromedial one pair of diverticula, can perceive an object into the mouth of the air or chemical properties) . Lateral line: aquatic types, and a few anuran tadpoles have a lateral line organs. 7. Excretory organs to adapt to the incomplete nature of terrestrial One pair of kidneys is the excretion organs. Urination and semen in the male pipe, and has highlighted formation of the cloacal cloacal wall Bladder when amphibians in the water, the kidneys maintain the body through the urinary function of water balance; but in the land, the kidneys can not be solved water loss problem, and also on some bladder leakage yield function to solve the reabsorption of water However, the bladder can not compensate for leakage yield surface evaporation caused by water loss, thus amphibians Although long out on the land but not water. 8. Can not do without water mode of reproduction (Figure) Genital: the male urinary output by the testis and vas deferens and the composition of the pipeline; females by the ovaries and fallopian tubes are not connected with the composition of ovarian Sperm and eggs are excreted through the cloaca. In vitro fertilization and water for the general. Male and female gender in the reproductive season with a hold on the phenomenon, while rows of sperm and eggs in the water, And complete fertilization. The development of the fertilized egg must be in the water. Fertilized egg in the water development, structure and fish hatched tadpoles are similar (no limbs, gills, round robin, etc.) grow to a certain stage in metamorphosis, a profound change in each system, adapt to change by the preliminary adaptation of aquatic terrestrial adult stage (with the limbs, lungs breathing, incomplete double circle) (
Translated by Google
Category List
Lost tooth subclass: the oldest amphibians, the backbone of early amphibians, living in the Devonian to the Cretaceous, including the ancestors of reptiles. Shell vertebral subclass: ancient and specialized early reptiles, only to survive in the Carboniferous and Permian. Landslide subclass: Cong Triassic survived into modern times, including all existing amphibians, divided into no Amphipoda, Caudata and Anura. No Isopoda apoda (caecilians head gymnophiona): no foot and form habits of amphibians are like worms, may be history, but only the new generation of reliable fossils of modern distributed in tropical regions outside Australia. Kiss Lumbricidae rhinatrematids: the most primitive caecilians, located in South America. Fish, salamanders Section ichthyophiids: the more primitive caecilians, distributed in tropical Asia, is the only caecilians. Blind End Lumbricidae uraeoptyphlidae: distribution in India, between progress and between the original caecilians. Creep Lumbricidae scolecomorphids: distributed in equatorial Africa, the progress of caecilians. True Lumbricidae caeciliidae: progress caecilians, most types of projects are caecilians, one of the most widely distributed branches, distributed in tropical America, equatorial Africa, India and the Indian Ocean islands. Blind tour Lumbricidae typhlonectidae: The only aquatic caecilians, located in South America. Caudata caudata: a tail of amphibian life, little difference between juvenile and adult, including a variety of salamander and newt, appeared in the Jurassic, now mainly in the northern hemisphere, especially North America, followed by East Asia and Europe, may salamander gills hidden into the original sub-orders and progress salamanders suborder. Salamander gills hidden sub-orders cryptobranchoidea: mainly distributed in East Asia have the original tail amphibians. Hidden gills Hynobiidae cryptobrachidae: 2 3 species, namely in North America hidden salamander gills (American giant salamander), and the one kind of Chinese and Japanese giant salamander. Hynobiidae hynobiidae: 8 is more than 30 species, including small salamander, North salamander, salamander and other mountain streams, mainly in East Asia, North to the Arctic Circle, west to Iran, particularly rich in species in China. Salamander suborder salamandroidea: mainly distributed in North America, the progress of a tail amphibians, some members of the senior types or primitive types is not clear. Eel salamander Section sirenidae: specialty in North America, the body slender, no hind legs. Amphibious Hynobiidae amphiumidae: specialty in North America, raw slender body like eels, small limbs. Cave salamander Section proteidae: including Europe and North America mud hole salamander salamander, there is life outside the gills of aquatic amphibians. Blunt salamander Division ambystomatidae: specialty of the cave salamander in North America, some species can be maintained life-long larval characteristics, life in the water. Lu giant salamander Division dicamptonidae: specialty in North American cave salamander, salamander with blunt quite similar. No pulmonary salamander Division plethodontidae: a tail sub-orders of the biggest one subject, mainly in North America, Europe and Central and South America in a small number of distribution, but also Central and South America only a tail sub-orders. Salamandridae salamandridae: there is the most widely distributed amphibian tail, mainly in Eurasia, is also found in North Africa and North America. Anura anura: includes a variety of frogs and toads, larvae and adult great difference, only tadpoles with tail. Appeared in the Triassic, the vast majority of amphibians are such a modern, world-wide distribution, but the richest in Latin America, followed by Africa. Anura can be divided into sub-projects and the beginning of a new frog frog suborder, or further divided into sub-orders before the beginning of frog frog suborder, the negative sub-sub-orders and hoe foot toad toad suborder. For the division of subjects have some different views. Beginning frog suborder archaeobatrachia Slip soles laevis Division leiopelmatidae: the most primitive Anura, including New Zealand and North America slip soles tail toad toad, two and sometimes as a separate section. Toad tongue plate section discoglossidae: China's most primitive Anura, including maxima and toad tongue plate, sometimes as two separate subjects. Negative sub-toad suborder pipoidea: Negative sub-toad Division pipidae: primitive Anura, including South America and Africa, the negative sub-toad Xenopus laevis. Different tongue toad Division rhinophrynidae: Mexico's only points toad tongue, represented by different, sometimes into the negative sub-toad Division. Hoe foot toad suborder pelobatoidea Hoe foot toad Section pelobatidae: include hoe foot toad and the toad angle, sometimes as two separate subjects, including horn toad particularly rich in our country. Together with toad Section pelodytidae: In Europe and the Caucasus have an effect, sometimes enough to dig into the toad Division. New frog suborder neobatrachia Fine toe toad Division leptodactylidae: the biggest one section of amphibians, including a variety of animals like frogs and toads, located in South America. Toad turtle Branch myobatrachidae: located in Oceania, is small toe corresponding members of the toad in Oceania. Serbian tongue Ranidae sooglossidae: distributed in the Seychelles Islands, taxonomic status uncertain, may have a toad and turtle related. Marsh frogs Section heleophrynidae: distributed in southern Africa the most, taxonomic status uncertain, may have a toad and turtle related. Hyla Section hylidae: amphibians second section, the distribution of a wide range of arboreal frogs, the majority located in the Americas, followed by Oceania, with Oceania members sometimes as a separate section. With Ranidae centrolenidae: Latin America's small arboreal frogs. Warts Ranidae allophrynidae: South America, the small branches. Short head toad Division brachycephalidae: South America, small branches, size small. Darwin Ranidae rhinodermidae: South America, the small branches. More knuckle toad Division pseudidae: South America, small branches, known as the unreasonable frog, tadpole into a frog than the larger. Poison dart frogs Section dendrobatidae: Latin America, small frogs, known to the strong toxicity. Bufonidae bufonidae: wide distribution of large branches, but does not appear in Australia, Madagascar and some oceanic islands. Ranidae ranidae: the most widespread amphibians, almost every continent, also appeared in some of the islands, the northernmost reach the Arctic Circle, in Australia only in the north. Tree Frog Branch rhacophoridaae: Asian and African tropical arboreal frogs, Hyla form habits of close, but closer to Ranidae kinship. African Tree Frog Branch hyperoliidae: Africa and the nearby islands of arboreal and terrestrial frogs. Section Ranidae arthroleptidae: African frogs, sometimes into the Ranidae. Ji Ranidae microhylidds: a large section of small frogs are widely distributed, including amphibians in most genera.
apodia