Chapter 1 : Fishes, Amphibians, Reptiles by Lisa OConnor on Prezi Grzimek's Animal Life Encyclopedia: Volume 5: Fishes II and Amphibians [Bernhard (Editor) Grzimek, Maps full-colour drawings] on blog.quintoapp.com *FREE* shipping on qualifying offers. The three major amphibian clades -- frogs, salamanders and the worm-like caecilians -- have each diverged greatly, but share several common characteristics. Unshelled Eggs Living amphibians produce much different eggs than strictly terrestrial organisms like reptiles do. The amphibian egg lacks a calcified shell, consisting mostly of jelly -- making it susceptible to rapid desiccation if exposed to the air. While most frogs and salamanders deposit their eggs directly into the water, some species have adapted methods for terrestrial egg deposition. Some terrestrial salamanders deposit their eggs in damp locations under rocks and logs. Some rainforest-dwelling frogs attach their eggs to plant leaves; as they hatch, the young tadpoles drop directly into the water. Amphibians that lay completely terrestrial eggs undergo metamorphosis inside the egg and hatch as fully formed, miniature adults. Permeable Skin While caecilians have scales similar to fish, most other amphibians have moist, permeable skin. This forces most species to live in moist or aquatic habitats; otherwise, they would quickly dehydrate as water is lost through the skin. In order to colonize arid habitats, some frogs -- namely waxy monkey frogs Phyllomedusa sauvagil -- have developed a protective mechanism: The lipid helps retard water loss, essentially forming a cocoon around the animal. Many amphibian species produce poisons from glands in the skin that they use to protect themselves from predators; some species -- like some poison dart frogs Dendrobates sp. Carnivorous Adults While some tadpoles and larval salamanders are filter feeders that consume plant and animal material; all adult amphibians are carnivores. While most amphibians consume invertebrates like insects, arachnids and earthworms, some eat small vertebrates as well. American bullfrogs Rana catesbeiana are known to eat snakes, fish, rodents and other bullfrogs. Distribution Amphibians are found in most parts of the world, but their global distribution shows greatly varying diversity from region to region. Most areas with high amphibian diversity have a few common characteristics, namely warm climates with high annual rainfall. The southeastern United States is the epicenter of salamander diversity, and the numerous mountains, valleys and small tributary streams of the region have allowed significant speciation to occur as habitats are often geographically isolated from each other. Courtship Rituals Frogs are well known for their nightly choruses; males typically move to potential breeding sites and begin calling to attract females. When the females approach, the males clasp them around the back and fertilize the eggs as they are deposited. Salamanders do not vocalize, but many species have ritualized courtship behaviors; some terrestrial species engage in complex dances, but the most developed rituals occur in aquatic species. Page 1
Chapter 2 : Five Characteristics of Amphibians Animals - blog.quintoapp.com This item: Grzimek's Animal Life Encyclopedia, Vol. 5: Fishes II, 2nd Edition by Michael Hutchins Hardcover $ Only 1 left in stock - order soon. Sold by Fibat Trade and ships from Amazon Fulfillment. Back to Animals What are amphibians? Amphibians are a class of animals like reptiles, mammals, and birds. They live the first part of their lives in the water and the last part on the land. When they hatch from their eggs, amphibians have gills so they can breathe in the water. They also have fins to help them swim, just like fish. Later, their bodies change, growing legs and lungs enabling them to live on the land. The word "amphibian" means two-lives, one in the water and one on land. Amphibians are Cold-blooded Like fish and reptiles, amphibians are cold-blooded. They must cool off and warm up by using their surroundings. Growing up from Egg to Adult Most amphibians hatch from eggs. After they hatch, their bodies are still in the larvae stage. In this stage they are very fish like. They have gills to breathe under water and fins to swim with. As they grow older, their bodies undergo changes called metamorphosis. They can grow lungs to breathe air and limbs for walking on the ground. Stages of a Frog As an example of metamorphosis, we will look at the frog: They generally have a short body, webbed fingers and toes, bulging eyes, and no tail. Frogs are good jumpers with long powerful legs. Toads are a type of frog. Two species of frogs are the American bullfrog and the poison dart frog. Salamanders - Salamanders look a bit like lizards. They have skinny bodies, short legs, and long tails. Salamanders can re-grow lost limbs and other body parts. They like wet, moist areas like wetlands. A newt is a type of salamander. They look a lot like snakes or worms. Some of them can be long and reach lengths of over 4 feet. They have a strong skull and a pointed nose to help them burrow through dirt and mud. Where do they live? Amphibians have adapted to live in a number of different habitats including streams, forests, meadows, bogs, swamps, ponds, rainforests, and lakes. Most of them like to live in or near water and in damp areas. What do they eat? Adult amphibians are carnivores and predators. They eat a variety of food including spiders, beetles, and worms. Some of them, like frogs, have long tongues with sticky ends that they flick out to catch their prey. The larvae of many amphibians mostly eat plants. It can grow to 6 feet long and weigh pounds. The largest frog is the Goliath Frog which can grow to 15 inches long not counting the legs and weigh over 8 pounds. The smallest amphibian is a frog called the paedophryne amauensis. It is about 0. Fun Facts about Amphibians Most amphibians have thin, moist skin that helps them to breathe. Amphibians are considered vertebrates as they have a backbone. Frogs swallow their food whole. The size of what they can eat is determined by the size of their mouths and their stomach. Frogs cannot live in salt water. All amphibians have gills, some only as larvae and others for their entire lives. It is a myth that you can get warts from touching a frog or toad. A group of frogs is called an army. This makes them very sensitive to air and water pollution. Page 2
Chapter 3 : Amphibian - Wikipedia Start studying Fishes and Amphibians II (M). Learn vocabulary, terms, and more with flashcards, games, and other study tools. Herpetology includes turtles, snakes, lizards, tortoises, amphisbaenids, crocodiles, toads, frogs, caecilians, newts and salamanders. The name reptile, refers to creeping or crawling animals. The name amphibian refers to dual modes of existence. At one time, reptiles and amphibians were zoologically classified as reptiles due to their many similarities. It is speculated that reptiles transitioned from amphibians some 50 million years ago, which perhaps explains why there are so many commonly shared characteristics. Both are ectothermic cold-blooded meaning their internal sources of heat are so insignificant that they must rely upon external sources to regulate their body temperature. Body heat regulation is primarily required for operation of their metabolic processes. Chordata animals that possess a spinal column: Both reptiles and amphibians are vertebrates possessing a central vertebral column. Skin color alteration by concentrating or dissipating melanin is possible in many amphibians and reptiles. Altering their skin coloration aids in camouflage and can help thermoregulation of body temperature. Many lizards reptiles and frogs amphibians have sharp eyesight which is crucial for their precise capture of prey by flicking their tongues. Both reptiles and amphibians use camouflage, biting and inflating of the body to avoid predation. Lizards reptiles and salamanders amphibians both have the ability to autotomize which is a voluntary removal of the tail as a defensive response. One common defense is mimicry where animals that have no innate defensive protection mimic the bright colors of dangerous animals. For example, a harmless king snake might appear as a venomous coral snake. The differences between reptiles and amphibians are challenging to identify. The below lists are an attempt to work through the haziness of distinction: Photo by Stephen G. This condition is called brumation. Snakes are able to disjoin their upper and lower jaw to accommodate swallowing large prey whole. Multiple vertebra in the neck, allowing articulation. Dry, scaly, watertight skin. Exposed parts are covered by bony scutes. Leathery, soft or hard eggs laid on land or maintained inside the body until hatching. The reptile egg is self-contained and protects the embryo from dehydration. Metamorphosis profound change in form: Reptiles have no larval stages. Some tortoises have reportedly lived more than years. The popular smooth green snake Opheodrys vernalis are reportedly living up to 15 years in captivity. Three layers of protection are normally used by reptiles. This is where the reptile evades danger through playing dead or retreats into a protective shell. This is when the reptile alerts potential predators by releasing a foul smell; or they hiss and shake their tail tip like the rattlesnake. Several species of the horned lizard Phrynosoma, are able to squirt foul tasting blood from their eyes to ward off predators. The dispensing of blood is called ocular autohemorrhaging. When warnings fail, some reptiles attack. This organ is located on the roof of the mouth. It captures chemical molecules for the purposes of locating mates, predators, and prey. It is speculated that some amphibians Plethodontid salamanders may also have a similar, but convoluted capability. Some snakes have thermoreceptors sensing heat located on their face that allows them to find prey in total darkness. Noble Amphibians have moist, smooth or rough skin. Breathing via gills, lungs or through the skin which is called cutaneous respiration. Their vascularised skin must be moist for this to work. The Lungless salamander Plethodontidae conducts respiration through cutaneous means and tissues within its mouth. Amphibians attempt to swallow their food whole but some have exclusive teeth called pedicellate teeth. Single vertebra in the neck which limits head articulation. Moist, smooth or rough skin sometimes with sticky mucous glands that secret waterproof coating to keep skin moist. Oxygen and CO2 can be exchanged through their skin. Soft eggs normally laid in water or in damp media. The amphibian egg is a yolk sac enveloped in one or more layers of a clear, jelly-like covering. The egg capsule is permeable to water and gases. Most amphibians use gills while developing their lungs. Some salamanders such as the mudpuppy Necturus maculousus retain their gills throughout their lives which is called neoteny. The Japanese giant salamander Andrias japonicus lacks natural predators and is speculated to live about 80 years. The American bullfrog Rana catesbeiana lives about eight years. Nocturnal activity and aposematic coloration by many amphibians helps avoid predation. Slippery skin makes it difficult Page 3
for a predator to grasp. When grabbed, the amphibian secrets a vile tasting, sometimes toxic substance through the skin, hopefully resulting in rejection by a predator. Tetradotoxin, produced and released through the skin by newts is deadly to reptiles, fish, birds and mammals ingesting the substance. Some amphibians, using their lateral line such as a tadpole may sense water pressure changes to locate prey. It is estimated that there are more than 8, reptiles and 6, amphibians inhabiting the Earth. They are as small as a dwarf gecko Sphaerodactylus or Paedophryne amauensis and as large as the Chinese Giant Salamander Andrias davidianus or saltwater crocodile Crocodylus porosus. Page 4
Chapter 4 : Differences Between Reptiles And Amphibians Identify characteristics of amphibians. Amphibians are vertebrate tetrapods. Amphibia includes frogs, salamanders, and caecilians. The term amphibian loosely translates from the Greek as "dual life," which is a reference to the metamorphosis that many frogs and salamanders undergo and their mixture of aquatic and terrestrial environments in their life cycle. The following points highlight the top six characteristics of amphibians. The amphibians are ectothermic vertebrates. Dermal scales are present in some members of apodans e. Head distinct, trunk elongated, neck and tail may be present or absent e. Body with 2 pairs of pentadactylous limbs except posterior pair in Sirenidae and total absent in Gymnophiona. Fore limbs are provided with 4 digits and hind limbs with 5 digits. Digits are clawless except African toad, Xenopus and in larval forms of an Asiatic urodele, Onychodactylus. The eyelids are present in terrestrial amphibians. The tympanic membrane or tympanum is absent in urodeles, apodans and in some anurans e. The tympanum is prominent in most of anurans. Lateral line system is present in larvae of air-breathing forms, and in the per-ennibranchiate urodeles e. Median fins are usually present in the larvae but not supported by fin-rays. Head with a pair of nostrils leading into buccal cavity. The gut ends into cloaca. Respiration is performed by lungs in most adult amphibians. In the larval stages, and in the per-ennibranchiate urodeles the external gills help in respiration. In some salamanders Salamandra atra and all plethodontids where lungs are absent, reparation is performed exclusively by skin and pharynx. RBC are large, nucleated and oval. The RBC of Proteus measures about 58 pm in diameter. Heart is 3 chambered with 2 auricles and an undivided ventricle. One sinus venosus and one conus arteriosus are present. Kidney is opisthonephric type. In female adult amphibians the archinephric duct is lost, the products of the ovary are carried by the oviduct. A ventral cloacal urinary bladder is present in amphibians, and the bladder has the capacity for water resorption. The brain is unspecialized, mainly in urodeles. The corpus striatum is small. The pineal body is well- developed in anurans. Double occipital condyles of exoccipitals are present in the skull. Jaw suspension is autostylic type. Close otic notch is present. Post temporal fossa and ectopterygoid are present. The tympanum, if present, connected with the inner ear through a rod-like stapes or columella hyomandibula of fish, helps in sound transmission. Pedicellate type of teeth are unique in all modern amphibians except in a group of salamanders of the genus Siren, and two genera of the frogs, Phyllobates and Ceratophrys. The pectoral girdle is freed from the skull and does not articulate directly with the vertebral column. The sacral region includes a single vertebra. Most of the extant amphibians have lost their ribs. True sternum is absent. Vertebrae are amphicoelous type in apodans, mostly procoelous and opisthocoelous in urodeles, and superficial procoelous type in most anurans. Fertilization is mostly external in some urodeles and in anurans, and mostly internal in apodans and in some urodeles Ambystomatidae. Mostly are oviparous, and a few are viviparous e. Mostly amphibians lay eggs in moist microhabitats or in water, and for metamorphosis water is necessary. Eggs are large and yolk is moderate amount â mesolecithal. Cleavage is holoblastic but unequal. Amnion and ailantois are absent anamniotic. An aquatic larval stage tadpole with external gill is present. In most amphibians, metamorphosis takes place in many forms. In Urodela, the lowest chromosome number in Taricha is 22, and in Onychodactylus japonicus and Ranoden sibiricus, the number is In Anura the lowest and the highest chromosome numbers have been recorded in the family Ranidae. Skin for respiration and Water conservation: The moist, glandular skin is permeable to water, thus facilitates the exchange of oxygen and carbon-dioxide. The body fluids of aquatic amphibians are hypertonic, that is higher in concentration to the freshwater. Water constantly enters within the body through the gills, oral membrane and moist permeable skin and some water enters inside the body with food. Amphibians do not drink or scarcely drink water. The urine of these anurans is hypo-osmotic in relation to the blood plasma. So anurans actively resorb solutes from the renal tubular fluid and also resorb water from the urine, to maintain the balance of water within the body. The fishes and amphibians are called as Anamniota because of the lacking of amnion and ailantois around the eggs. Extinct and living amphibians have a worldwide distribution. Living amphibians are absent from Antarctica and some oceanic islands. Duellman and Trueb, Halliday and Adler Page 5
have reported species which are classified into genera in 34 families. Page 6
Chapter 5 : Top 6 Characteristics of Amphibians Phylum Chordata Grzimek's animal life encyclopedia / Vol. 5, Fishes II and amphibians / edited by Bernhard Grzimek, Werner Ladiges ; translated from the German by David R. Martinez. There are about 6, species of reptiles, and they make up one of the classes of vertebrates. Some of the major species of animal in in this class are alligators, crocodiles, lizards, snakes, turtles, and the tuatara. Amphibians are animal with mostly scaleless skin that lives part of its life in water and part on land. There are about 3, kinds of amphibians, and they make up one of the classes of vertebrates. Some of the major species of animal in in this class are frogs, toads, salamanders, and caecilians. Most amphibians hatch from eggs laid in water or moist ground, and begin life as animal living in water. Through a process of metamorphosis, the larvae change into adults that look very different from the larvae. Most of the amphibians take to living on becoming adult, while some continue to live in water. Almost all return to water for reproduction. For example, crocodiles are reptiles, yet they are capable of living in water as well as on land. Some sorts of reptiles are alligators, crocodiles, turtles, and snakes. And some amphibians are salamanders, toads, frogs etc. One difference is between the structures of their skin. Reptiles are covered with scales, shields, or plates and their toes have claws. Amphibians, on the other hand, have wet, glandular skins, and their toes lack claws. Another difference is between the eggs. Eggs of reptiles have a thick, solid covering that protects the developing embryo from moisture loss, even on dry land. In contrast, the eggs of amphibians lack a hard outer covering. For this, they must be laid in water or damp places. The eggs of a reptile have hard leathery shells which protect the young inside, and are often laid in buried, insulated nests. Amphibians lay soft eggs without an external covering, and the eggs are usually attached to the stems of aquatic plants. Though, some reptile species can swim, they do not take to water as readily as amphibians do, and can be found in a wider range of locations. Reptiles also have more diverse body types, ranging from limbless snakes to giant dinosaurs, and they are primarily land animals. When reptile eggs are hatched, the young look like miniature adults. As the young grow up, they will mature into scaly animals with fully developed lungs and dry skins. When an amphibian hatches, it initially emerges in the form or a tadpole, an aquatic larva which breathes through gills. Tadpoles cannot survive out of water, but, as they grow and mature, they get bigger, grow limbs, and lose their tails. Finally, they develop lungs and turn into mature amphibians, which will spend much of its life in and around the water. Amphibians are animals that can live on both land and water such as a frog and they have a soft skin instead of coarse scales like a reptile. Reptiles include alligators, crocodiles, turtles, and snakes. Amphibians include salamanders, toads, and frogs. One difference between the two is the structure of their outer skin. Reptiles are covered with scales, shields, or plates, and their toes have claws. Amphibians, on the other hand, have moist, glandular skins, and their toes lack claws. The eggs of reptiles have a thick, hard shell that protects the developing embryo from moisture loss, even on dry land. In contrast, the eggs of amphibians lack a hard outer covering and, thus, must be laid in water or in damp places. Finally, young reptiles are miniature replicas of their parents in general appearance, although not always in coloration and pattern. Juvenile amphibians, however, pass through a larval wormlike, usually aquatic, stage before they metamorphose change in form and structure into the adult form. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. The Encyclopedia of Reptiles and Amphibians, preface. Access hundreds of thousands of answers with a free trial. Page 7
Chapter 6 : What is the difference between a reptile and an amphibian? enotes The fishes and amphibians are called as Anamniota because of the lacking of amnion and ailantois around the eggs. Geographical distribution: Extinct and living amphibians have a worldwide distribution. Essential Questions The student will need to consider: What do reptiles and amphibians share? How are they different? This activity will help students compare and contrast the behavior and structure of amphibians and reptiles of Utah. Main â and Contrast chart pdf Additional Resources: Utah Division of Wildlife Resources: After the video, ask the students for ideas as to what they learned. Reptiles and amphibians can be told apart by the following: Next, pass out the Reptile and Amphibian Venn Diagram activity. This should help students differentiate between reptiles and amphibians â User Rating: Write a list of the similarities and differences between the reptile and amphibian chosen. Invent new reptiles and amphibians. Sketch how they would look and their â User Rating: A Field Guide to Reptiles and Amphibians. Tidewater Publishers, Centreville, MD. A Thousand â User Rating: Exploring Animals - â the similarities and differences among mammals, birds, reptiles, and amphibians. Introduction Today scientists have documented over one million different kinds of animals, and the numbers are still growing. Today the students are going to learn about four groups of these animals: Amphibians, Reptiles, Birds, and Mammals â. Have the students name some amphibians. Possible responses are frogs, toads, newts, and salamanders. Reptiles Reptiles have scales and are rough and dry. The scales are â User Rating: K-2 Reviled and Revered, Lesson Plan 3 - â are alike and different. List several examples each of reptiles and amphibians. Describe how reptiles and amphibians are similar to and different from one another. Books and other reference materials on herps. Pencils and â User Rating: A Golden Guide, by Herbert S. Zim and Hobart M. What makes a bird a bird? There are some obvious and not â User Rating: Page 8
Chapter 7 : Comparative Vertebrate Anatomy - Lecture Notes 5 Early amphibians, a crucial link from fish to terrestrial reptiles, were the first animals to leave the sea and venture onto the land. Reptiles (meaning "to creep stealthily under cover of darkness") are a group of animals that have scales (or modified scales), breathe air, and usually lay eggs. The term was initially used as a general adjective for animals that could live on land or in water, including seals and otters. Amphibia in its widest sense sensu lato was divided into three subclasses, two of which are extinct: Jurassic to presentâ 6, current species in 53 families Caudata salamanders, newts and relatives: Jurassic to presentâ current species in 9 families Gymnophiona caecilians and relatives: Jurassic to presentâ current species in 10 families Triadobatrachus massinoti, a proto-frog from the Early Triassic of Madagascar The actual number of species in each group depends on the taxonomic classification followed. The two most common systems are the classification adopted by the website AmphibiaWeb, University of California, Berkeley and the classification by herpetologist Darrel Frost and the American Museum of Natural History, available as the online reference database "Amphibian Species of the World". Classification varies according to the preferred phylogeny of the author and whether they use a stem-based or a node-based classification. Traditionally, amphibians as a class are defined as all tetrapods with a larval stage, while the group that includes the common ancestors of all living amphibians frogs, salamanders and caecilians and all their descendants is called Lissamphibia. The phylogeny of Paleozoic amphibians is uncertain, and Lissamphibia may possibly fall within extinct groups, like the Temnospondyli traditionally placed in the subclass Labyrinthodontia or the Lepospondyli, and in some analyses even in the amniotes. This means that advocates of phylogenetic nomenclature have removed a large number of basal Devonian and Carboniferous amphibian-type tetrapod groups that were formerly placed in Amphibia in Linnaean taxonomy, and included them elsewhere under cladistic taxonomy. The three modern orders are Anura the frogs and toads, Caudata or Urodela, the salamanders, and Gymnophiona or Apoda, the caecilians. It is anatomically very similar to modern frogs. The Lissamphibia are traditionally divided into three orders, but an extinct salamander-like family, the Albanerpetontidae, is now considered part of Lissamphibia alongside the superorder Salientia. Furthermore, Salientia includes all three recent orders plus the Triassic proto-frog, Triadobatrachus. List of prehistoric amphibians Top: Restoration of Eusthenopteron, a fully aquatic lobe-finned fish Bottom: Restoration of Tiktaalik, an advanced tetrapodomorph fish The first major groups of amphibians developed in the Devonian period, around million years ago, from lobe-finned fish which were similar to the modern coelacanth and lungfish. Some fish had developed primitive lungs to help them breathe air when the stagnant pools of the Devonian swamps were low in oxygen. They could also use their strong fins to hoist themselves out of the water and onto dry land if circumstances so required. Eventually, their bony fins would evolve into limbs and they would become the ancestors to all tetrapods, including modern amphibians, reptiles, birds, and mammals. Despite being able to crawl on land, many of these prehistoric tetrapodomorph fish still spent most of their time in the water. They had started to develop lungs, but still breathed predominantly with gills. Ichthyostega was one of the first primitive amphibians, with nostrils and more efficient lungs. It had four sturdy limbs, a neck, a tail with fins and a skull very similar to that of the lobe-finned fish, Eusthenopteron. Their lungs improved and their skeletons became heavier and stronger, better able to support the weight of their bodies on land. They developed "hands" and "feet" with five or more digits; [15] the skin became more capable of retaining body fluids and resisting desiccation. It is thought they may have propelled themselves with their forelimbs, dragging their hindquarters in a similar manner to that used by the elephant seal. Extensive swamps developed with mosses, ferns, horsetails and calamites. Air-breathing arthropods evolved and invaded the land where they provided food for the carnivorous amphibians that began to adapt to the terrestrial environment. There were no other tetrapods on the land and the amphibians were at the top of the food chain, occupying the ecological position currently held by the crocodile. Though equipped with limbs and the ability to breathe air, most still had a long tapering body and strong tail. They still needed to return to water to lay their shell-less eggs, and even most modern amphibians have a fully aquatic larval stage with gills Page 9
like their fish ancestors. It was the development of the amniotic egg, which prevents the developing embryo from drying out, that enabled the reptiles to reproduce on land and which led to their dominance in the period that followed. According to the fossil record, Lissamphibia, which includes all modern amphibians and is the only surviving lineage, may have branched off from the extinct groups Temnospondyli and Lepospondyli at some period between the Late Carboniferous and the Early Triassic. A molecular phylogeny, based on rdna analysis, suggests that salamanders and caecilians are more closely related to each other than they are to frogs. It also appears that the divergence of the three groups took place in the Paleozoic or early Mesozoic around million years ago, before the breakup of the supercontinent Pangaea and soon after their divergence from the lobe-finned fish. The briefness of this period, and the swiftness with which radiation took place, would help account for the relative scarcity of primitive amphibian fossils. In the water, the sideways thrusts of their tails had propelled them forward, but on land, quite different mechanisms were required. Their vertebral columns, limbs, limb girdles and musculature needed to be strong enough to raise them off the ground for locomotion and feeding. Terrestrial adults discarded their lateral line systems and adapted their sensory systems to receive stimuli via the medium of the air. They needed to develop new methods to regulate their body heat to cope with fluctuations in ambient temperature. They developed behaviours suitable for reproduction in a terrestrial environment. Their skins were exposed to harmful ultraviolet rays that had previously been absorbed by the water. The skin changed to become more protective and prevent excessive water loss. It has an average length of 7. Their metabolic rate is low and as a result, their food and energy requirements are limited. In the adult state, they have tear ducts and movable eyelids, and most species have ears that can detect airborne or ground vibrations. They have muscular tongues, which in many species can be protruded. Modern amphibians have fully ossified vertebrae with articular processes. Their ribs are usually short and may be fused to the vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, apart from a few fish-like scales in certain caecilians. The skin contains many mucous glands and in some species, poison glands a type of granular gland. The hearts of amphibians have three chambers, two atria and one ventricle. They have a urinary bladder and nitrogenous waste products are excreted primarily as urea. Most amphibians lay their eggs in water and have aquatic larvae that undergo metamorphosis to become terrestrial adults. Amphibians breathe by means of a pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They usually have long hind limbs that fold underneath them, shorter forelimbs, webbed toes with no claws, no tails, large eyes and glandular moist skin. The difference is not a formal one taxonomically and there are numerous exceptions to this rule. Members of the family Bufonidae are known as the "true toads". They are found worldwide except for polar areas. Future molecular studies should provide further insights into their evolutionary relationships. These are Ascaphidae, Bombinatoridae, Discoglossidae and Leiopelmatidae which have few derived features and are probably paraphyletic with regard to other frog lineages. These have certain characteristics that are intermediate between the two other suborders. Ninety-six percent of the over 5, extant species of frog are neobatrachians. This is a symplesiomorphic trait and they are no more closely related to lizards than they are to mammals. They range in size from the Chinese giant salamander Andrias davidianus, which has been reported to grow to a length of 1. The family Plethodontidae is also found in Central America and South America north of the Amazon basin ; [35] South America was apparently invaded from Central America by about the start of the Miocene, 23 million years ago. They may be terrestrial or aquatic and many spend part of the year in each habitat. When on land, they mostly spend the day hidden under stones or logs or in dense vegetation, emerging in the evening and night to forage for worms, insects and other invertebrates. A number of fossil cryptobranchids have been found, but there are only three living species, the Chinese giant salamander Andrias davidianus, the Japanese giant salamander Andrias japonicus and the hellbender Cryptobranchus alleganiensis from North America. These large amphibians retain several larval characteristics in their adult state; gills slits are present and the eyes are unlidded. A unique feature is their ability to feed by suction, depressing either the left side of their lower jaw or the right. As well as breathing with lungs, they respire through the many folds in their thin skin, which has capillaries close to the surface. They differ from the cryptobranchids by having fused prearticular bones in the Page 10
lower jaw, and by using internal fertilisation. In salamandrids, the male deposits a bundle of sperm, the spermatophore, and the female picks it up and inserts it into her cloaca where the sperm is stored until the eggs are laid. The family Salamandridae includes the true salamanders and the name " newt " is given to members of its subfamily Pleurodelinae. Members of this order are eel -like aquatic salamanders with much reduced forelimbs and no hind limbs. Some of their features are primitive while others are derived. Despite this, the eggs are laid singly, a behaviour not conducive for external fertilisation. These are long, cylindrical, limbless animals with a snake- or worm-like form. It has rudimentary eyes covered in skin, which are probably limited to discerning differences in light intensity. It also has a pair of short tentacles near the eye that can be extended and which have tactile and olfactory functions. Most caecilians live underground in burrows in damp soil, in rotten wood and under plant debris, but some are aquatic. Others brood their eggs and the larvae undergo metamorphosis before the eggs hatch. A few species give birth to live young, nourishing them with glandular secretions while they are in the oviduct. Local thickenings often called warts are common, such as those found on toads. The outside of the skin is shed periodically mostly in one piece, in contrast to mammals and birds where it is shed in flakes. Amphibians often eat the sloughed skin. The similarity of these to the scales of bony fish is largely superficial. Lizards and some frogs have somewhat similar osteoderms forming bony deposits in the dermis, but this is an example of convergent evolution with similar structures having arisen independently in diverse vertebrate lineages. Granular poison gland, D: Connective tissue, E: Stratum corneum, F: Dermis Amphibian skin is permeable to water. Gas exchange can take place through the skin cutaneous respiration and this allows adult amphibians to respire without rising to the surface of water and to hibernate at the bottom of ponds. The secretions produced by these help keep the skin moist. In addition, most species of amphibian have granular glands that secrete distasteful or poisonous substances. Chapter 8 : Reptiles and Amphibians Lessons - LessonCorner blog.quintoapp.com temp of fishes, amphibians, reptiles close to temp of environmentâ mammals and birds have warmer temp than environment blog.quintoapp.comermsâ an animal whose body does not produce a lot internal heatâ temp changes with environment. Chapter 9 : Amphibians for Kids: Frogs, Salamanders, and Toads The amphibians bridged the gap from the totally aquatic existence of the ancient fishes to the reptiles that were destined to adapt to a life totally on land, even to arid rather than moist conditions required by the amphibians. Page 11