Main Classes of Chordates Amphibians Reptiles Mammals Birds Fish

Let's take look at some characteristics of the five main classes of chordates, which are animals that have backbones. These include amphibians, reptiles, mammals, birds, and fish. And yes, technically we're looking at eight classes because fish are divided into four. So, welcome to Mooumath and science. Do you know what almost all these amphibians have in common? Examples of amphibians include frogs, toads, salamanders, newts, and caecilians. So, now let's take look at some common characteristics. First, all amphibians are vertebrates. Next, the name amphibian means two lives. They are born in the water and then metamorph into adults that can live on land. Adult amphibians have to live near the water since they need steady moisture in order to survive. They lay soft, jelly-like eggs, and fertilization and development of young ones take place outside the body of the frog. Most of these eggs are laid in water, but all of the eggs must be kept moist. Amphibians have two circulatory routes, one for oxygenation of the blood through the lungs and skin, and the other to take oxygen to the rest of the body. They are cold-blooded or ectothermic. They do not have the internal mechanisms to regulate their own body temperatures. Most amphibians have lungs, and most can also breathe through their skin. Amphibians are mainly carnivores and feed almost on anything that moves and that they can swallow. Some of these foods includes include spiders, earthworms, beetles, and caterpillars. Reptiles can be both frightening and also pretty cool. In this video, I'd like to talk about what makes reptile reptile. There are four main reptile groups. They include turtles and tortoises, snakes and lizards, crocodiles and alligators, and the tuatara. Now, let's begin to look at some characteristics. Reptiles are egg-laying animals. Although some snakes do bear live youngs, but strange fact, the eggs actually hatch inside the mother's womb. Reptile eggs are amniotic. This means that they have fluid-filled bag surrounding the embryo. This prevents the egg from drying out, so they can lay their eggs on dry land. Reptile skin has scales with no hair or feathers. Their scaly skin protects them from drying out. Reptiles shed their skins as they grow, often in one piece. Almost all reptiles have four legs, or the fancy name is tetrapod. Most have short legs and swing their back from side to side when they walk. Most reptiles have three-chambered hearts. Alligators and crocodiles, however, have four-chambered heart, much like birds and mammals. Reptiles are ectothermic or cold-blooded, and they have to use the surrounding environment to warm and cool themselves. And also, reptiles are vertebrates, meaning they have vertebrae column that protects the spinal cord. All these animals have in common. They can all be classified as mammals. There's great deal of variety among mammals. This hog-nosed bat weighs only 1.5 The largest mammal, blue whale, can weigh up to 300,000 lb. wolf may travel an area 400 square miles, but mole rat may never leave its burrow. horse will eat plants its entire life, and lion is an efficient hunter. There are over 4,000 different species of mammals, but what makes mammal mammal? First, all mammals have backbone and spinal cord. The vertebrae protects the spinal cord, which delivers electrical signals from the brain throughout the body. Next, all mammals have hair. The hair protects the mammal from sun, freezing rain, and slows evaporation of moisture. Mammals have special glands called mammary glands that secrete milk, which allows mammals to provide milk to their young. Mammals also have sweat glands that help them cool down when it's heart. This heart has two upper chambers called atria and two lower chambers called ventricles. The four-chambered heart allows the mammal to pump large volumes of blood and oxygen throughout the body. Mammals have different types of teeth, and these teeth serve many different purposes. Mammals are endothermic or warm-blooded, which means they can generate internal heat to moderate their body temperature. Their body temperature does not rely on their surroundings, much like reptiles do. Mammals have unique jaw shape. Their lower jaw or mandible forms joint. In other words, it articulates with the skull. They also have an arch called the zygomatic arch. Let's take look at couple examples of the zygomatic arch. Here it is with the human and cat. Almost all mammals, not all, have external ears, which allow them to hear. The platypus does not have external ear ears, but hears with its bill. Along with several marine mammals like the dolphin, also do not have external ears. However, with many mammals, the large external ears allow them to hear, much like these ears on the elephant. They also help the elephant cool down when it's Birds range in size from this tiny 2-in hummingbird to 9-ft ostrich. There are over 10,000 species of birds, and it is estimated that there are 50 billion birds on planet Earth. So, what are some common characteristics of birds? Let's begin. Birds are the only living animal with feathers. Feathers help birds fly, but they also help them show off, blend in, stay warm, and keep dry. All birds lay eggs. Birds are vertebrates, meaning they have spinal cord and backbone. Almost all birds have four limbs modified as wings, but not all birds can fly. And there are couple birds that don't have wings. Next, they are endothermic, meaning they are warm-blooded, which means they can generate their own heat and are not dependent on their surroundings. The lower and upper jaws are modified into beak, and they have no teeth. Their hearts are four-chambered. They walk on two legs. Birds have lungs, and they digest their food using gizzard. Fish come in an amazing variety. There are roughly 34,000 species of fish, which is more than the combined total of mammals, amphibians, reptiles, and birds. Welcome to Mooumath and science in the characteristics of fish. So, let's get started with some common characteristics. First, fish are vertebrates. This means that they have vertebral column, which is group of vertebrae separated by mobile joints. Fish have fins, and these are used for balance and to help them propel forward and steer through the water. Most fish have two types of fins, single fins, which are found along the center line, and paired fins. Fish are cold-blooded, which means that they are ectothermic. This means that they are unable to regulate their body temperature and rely on the outside environment for their temperature. On the outside of the skin, most fish have scales. These overlapping rows and help protect the fish against injuries and infection. In order to breathe underwater, fish have developed gills. The gills are found on the side of the fish just behind the head and contain thousands of capillaries or tiny blood vessels. Water moves over these gills, which filter the oxygen out of the water and then into the fish's blood. Fish have an unique internal organ called swim bladder or maybe an air bladder. It's usually found near the abdomen, and it helps the fish move up and down in the water. Also, another common characteristic among fish is that they live in water. But, there are some fish that can spend large amount of time out of the water. Mudskippers, for instance, can eat and interact with each other on land. Thanks for watching, and remember, kindness multiplies kindness. Be kind to someone today.