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Biology

Anatomy of Amphibians | Skeleton, Respiratory System, Food Facts

Black Red Frog - Anatomy of Amphibians

However there are similarities between the anatomy of amphibians and relevant reptilian ancestors, but they are not the intermediate step in the evolution of reptiles from fishes.

Amphibians are found all over the world, except in Antarctica and Greenland. They are found both on land, and in freshwater. Frogs are the common amphibians. You can find frogs in water or near places that have water, like ponds and streams.

However, some frogs will never enter the water. They live mainly on land. Then, there are some that live in trees. Some frogs are burrowers. Frogs that live in cold places, hibernate during wintertime. Salamanders are found in North, South, and Central America, Europe, and Asia, and some species are found in Africa too. Caecilians are found in swampy places in most tropical parts of the world.

Anatomy of Amphibians: Skeleton

Amphibian’s skeletons are made of bones. They have fewer bones than their fishy ancestors, and over the years, the evolutionary changes in the amphibian family have gone in two directions. The frog family has a broad head, large eye sockets, short spine, no tail, and long hind legs.

Anatomy of Amphibians - Frog-Skeleton

The caecilian group has skeletons with small tubular skulls, tiny eye sockets, long spines, and no legs at all. The skeletons of salamanders and newts are adapted for a primitive form of walking. A frog’s skeleton, on the other hand, is specially adapted for leaping and swimming.

The backbone is the base of an amphibian’s skeleton and is made of vertebrae. Ribs still remain underdeveloped. Using a thorough study of the anatomy of Amphibians, and comparing the skeleton of modern amphibians with the fossils of ancient ones, it is possible to determine the era in which they lived.

The Respiratory System of Amphibians

Amphibians live on both land and water, and so, their respiratory system must allow them to take in oxygen not only from the air but also from water. Thus, they have a very complex respiratory system.

When amphibians stay in the water, they breathe through their skin, but once they come on land, they breathe with their lungs, and through the membranes in their mouth. Even when the lungs are used, amphibians obtain oxygen through their skin- and for this to be possible, the skin must remain moist at all times.

When an amphibian is in the larval stage, it uses gills for breathing. These gills later develop into lungs as the amphibian undergoes the changes that make it an adult. Some salamanders have neither gills nor lungs but breath through their mouths and skins.

Respiratory-System-of-Amphibians

To sum up, amphibians can get oxygen into their bodies in three different ways. The first way is by using the lungs, which are similar to ours. The second way is through their skin, and the last way is by using gills. Did you know that amphibians don’t breathe constantly as humans do? Instead, they just breathe now and then, when their body needs more oxygen.

For amphibians, water is essential for survival. To begin with, water keeps their skin moist, and they get the oxygen they need from the water that they absorb through their skin. Water is also vital for their reproduction.

This is because the eggs of amphibians do not have a hard shell so they need water to keep them from drying out, and to protect them from the rays of the sun. Some species of amphibians are aquatic and spend all their lives in water.

Others spend the beginning of their lives in water as larvae, and later undergo a change called metamorphosis, and move on to land. Since water is so important to them, amphibians like frogs seek out damp shady places to live in.

Others try to prevent water loss by burrowing underground. In spite of being so dependent on water, amphibians rarely drink it! Isn’t that strange?

Anatomy of Amphibians: Vivid colors

Amphibians can be red, blue, yellow, brown, or green and they come with spots, stripes, and many different types of markings. Some are darker on top with a completely different color and pattern underneath.

An amphibian’s color may vary with humidity too, becoming pale when warm and dry, and dark when cold and damp. There are several reasons why amphibians come in different colors.

A bright color is used to tell other animals whether a particular animal is poisonous or not. Tropical colors like reds, oranges, and blues are so bright that they can be seen from afar.

Blue-Frog Amphibians Color

These colors signal predators that the animal is poisonous, and shouldn’t be eaten. While studying the anatomy of amphibians we have also concluded that some of them have bright colors to scare their enemies away.

Many can change their coloring to mimic their surroundings so that their enemies can’t see them. Some frogs can only change their bottom half into a tropical color.

Food and Gulping

Amphibians depend mainly on their eyesight for their food. They will eat almost anything that is alive which they can swallow or gulp down. Insects, slugs, and earthworms form part of their everyday diet, while larger amphibians may eat small animals like mice. Some amphibians will even eat others of their own species!

A Frog Gulping Food

Generally speaking, amphibians tend to swallow or gulp their food as fast as they can- and also to eat until they are stuffed. The reason for this is that they want to eat as much as they can when food is plentiful, to make up for those times when food is scarce.

How do they survive?

One of the greatest dangers amphibians face is that of their skin drying out because of too much exposure to the sun. Their soft skin provides little protection against dehydration. If their skin dries up, they soon die. So amphibians inhabit regions that have plenty of dew and moisture.

Where temperature becomes high, and humidity low, or where dry and rainy seasons alternate, some amphibians become inactive until conditions are again favorable. Some are active by day, while others move about at night. Their activity is also influenced by temperature and humidity.

The enemies of amphibians include foxes, hedgehogs, storks, herons, snakes, and large spiders. Amphibians respond to danger in several ways. Some dive into the water or hide in dens. Others pretend to be dead or camouflage themselves by changing color. Others protect themselves with poisonous skin secretions or puff up to look large and frightening.

Humans are the most serious threat to amphibians. They are often destroyed when people drain marshes to kill mosquitoes and other insect pests. Amphibians are eaten in some countries and frog legs are a delicacy. Many amphibians are used in scientific experiments.

 

Biology

20 Mindboggling Fun Facts about Heart for Kids

Fun Facts about Heart

Fun Facts about Heart

The heart is the hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions move the blood through the body. In all humans, other mammals, and birds, the heart has 4 chambers while in fishes it is divided into two chambers.

Did you know that heart-related diseases or CVD account for 32% of all human deaths around the globe as of 2015? Isn’t that scary? Here is a list of 20 Amazing Fun Facts about Heart, check it out!

Fun Facts about Heart

#1-#10

#1 Xenographic transplants involve taking an organ from an animal and using it in a human being – a chimpanzee heart was transplanted into a man in Mississippi, the USA in 1964, but the patient died two hours later.

#2 Your right lung is larger than your left – this is because the left lung needs to make room for your heart. Did you know Your heart beats about 35 million times a year?

#3 The pressure created by your heart can squirt blood almost ten meters.

#4 The blue whale has the slowest heartbeat of any animal – it only beats four to eight times a minute.

#5 The heart is the only muscle that doesn’t take its signal from the nervous system – it has its own stimulator in the right atrium.

#6 The larvae of the pork tapeworm, hatched from eggs eaten in infected pork, can travel around the body and live in the brain, eyes, heart, or muscles.

#7 A giraffe has special valves in its arteries so that its blood can reach up to its head. Without them, it would need a heart as big as its whole body!

#8 About 70 milliliters (around 2.5 fluid ounces) of blood are spurted out of your heart with each beat.

#9 Your heart pumps around 182 million liters (48 million gallons) of blood in your lifetime – with an endless supply of blood, it could fill a swimming pool in less than a month!

#10 Nuttall’s poorwill is an American bird that hibernates in the winter, hiding in a crack in a rock. During this time, it uses only a thirtieth of the energy it uses in the summer and its heartbeat becomes so faint that it can’t be felt.

#11-#20

#11 When you sneeze, all your body functions stop – even your heart stops beating. A very long sneezing fit can cause a heart attack.

#12 Newts can re-grow body parts that are lost or damaged, including legs, eyes, and even hearts. Scientists who have studied how they do this think they might be able to persuade human bodies to do the same.

Newt

#13 In Vietnam, cobra hearts are a common snack. They can be eaten raw, even still beating, with a small glass of cobra blood or dropped into a glass of rice wine. The kidney is often included as an extra titbit.

#14 The Scottish dish haggis is made by cutting up the heart, lungs, liver, and small intestine of a calf or sheep and cooking it with suet, oatmeal, onions, and herbs in the animal’s stomach.

#15 During heart surgery in 1970, a patient with hemophilia (an inherited condition which stops the blood clotting) needed 1,080 liters of blood – nearly 15 baths full – as he kept bleeding.

#16 The poet Shelley drowned off the coast of Italy in 1822. His body was washed up, half-eaten by fish, and cremated on the beach by his friends. One of them cut his heart from the burnt body and gave it to Shelley’s wife who kept it all her life.

#17 The glass frog is lime green but has a completely transparent stomach. It’s possible to see the blood vessels, the heart, and even check whether it’s eaten recently or might like a snack.

Glass Frog

#18 People who killed themselves used to be buried at a crossroads with a stake through their heart. It was thought that they couldn’t go to heaven, and the cross-roads would confuse their ghost so that it couldn’t find the way home to haunt anyone.

#19 A robotic caterpillar controlled by a joystick can be inserted through a small hole in the chest, and crawl over a person’s heart to inject drugs or install implants to heal any damage. Is it nanotechnology?

#20 Apart from the heart, an Egyptian mummy doesn’t have any internal organs left inside the body. The others were removed and put into separate canopic jars that were buried with it. You can continue reading 10 More interesting facts about the Human Digestive System.

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Biology

Dinosaurs – Facts about the Ruling Reptiles & Their Types

Dinosaurs

Dinosaurs fossils were probably discovered by the ancient Chinese, Romans, and Greeks. However, no one really recognized them as belonging to an extinct animal. Much later in 1676, a huge thigh bone was found in England by Reverend Plot.

It was thought that the bone belonged to a ‘giant’ but was probably from a dinosaur. The first dinosaur to be described scientifically was Megalosaurus, named in 1824, by William Buckland.

The name ‘dinosaur’ which means ‘terrible lizard,’ was actually coined by Richard Owen. In 1838, William Parker Foulke found the first nearly complete dinosaur fossil remains in New Jersey, USA. Since Buckland’s original discovery in 1819, approximately 330 different dinosaur genera have been discovered thus far.

The Ruling Reptiles

The Jurassic Period started around 205 million years ago and is known as the time when dinosaurs, who were reptiles, ruled the Earth. Dinosaurs were now much larger, which clearly put them at the top of the food chain.

Some of the largest dinosaurs of the Jurassic age were the herbivore plant-eating sauropods. Thanks to the abundant plant life, massive herbivores such as the brachiosaurus, diplodocus, and apatosaurus had no shortage of food.

The fiercest among the carnivorous dinosaurs were extremely large theropods like the allosaurus and the ceratosaurus. The allosaurus was probably the top Jurassic predator of its time, and with the largest specimen coming in at a length of over 9 meters and its prey was most likely the large herbivores such as the sauropods.

Flying reptiles like the pterosaurs were still the dominant air species. It was the first feathered flying species, and clearly an evolutionary step towards the bird species.

Marine reptiles consisted mainly of the plesiosaurs, ichthyosaurs, large marine crocodiles, variations of modern-day sharks, as well as cephalopods which are relatives of today’s squid and octopus species.

Different Types of Dinosaurs

Types of Dinosaurs

There were many different kinds of dinosaurs. The smallest types were about the size of a chicken, and the largest was over 100 feet, or 30 meters long.

  • Some ate only meat and were known as ‘carnivores’.
  • Some ate only plants and were herbivores.
  • Others ate both plants and meats and were ‘omnivores’.

Herbivorous dinosaurs were usually larger in size and had longer necks than the others as they evolved to scare carnivorous dinosaurs who hunted them for food. They usually lived in herds and had short and blunt teeth for chewing on plants. They probably swallowed stones to aid them in their digestion.

Carnivorous dinosaurs were large in size, and they usually walked on their hind limbs. They had long and sharp teeth for killing their prey and ripping their flesh for food. Omnivorous dinosaurs were not as large as carnivorous dinosaurs. They usually walked on their hind limbs, but they did not have specific kinds of teeth as they consumed plants, animals, and even eggs.

They are also classified as being lizard-hipped or bird-hipped. Some common dinosaurs are the Acrocanthosaurus, tyrannosaurus rex, spinosaurus, brachiosaurus, and diplodocus. Till now, more than 700 different species of dinosaurs have been identified.

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Biology

Popular evolution theories before Charles Darwin

Lamarck - evolution theories

Early scientists were not interested in any theories of evolution or not even aware of such concepts. At first, they were even reluctant to accept the idea that some animals had become extinct. According to the Bible, even when a great flood covered the Earth, Noah had managed to save a male and female of all species to ensure that no animal would become extinct. When the first fossils of unknown animals were discovered, it was believed that these animals still existed in some unexplored regions of the Earth.

However, the discovery of fossils of giant animals like the mastodon shook this belief, as it was unlikely that there were unexplored regions large enough to hide such animals. French scientists were the first to accept that these giant animals might have roamed the Earth thousands of years ago, and become extinct due to a variety of causes. Slowly, this idea came to be accepted worldwide. Scientists began their work on evolution theories, and Lamarck was first among them. Later among all these evolution theories, Theory of Evolution by Charles Darwin became popular and most accepted to date by the scientific community.

Jean Baptiste Lamarck

Jean Baptiste Lamarck was a French scientist who developed a theory of evolution at the beginning of the 19th century. His theory involved two ideas. The first was the law of use and disuse, which stated that a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used, eventually disappears. The second law was the law of inheritance of acquired characteristics. It stated that any feature of an organism that is improved through use is passed to its offspring.

However, Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that all organisms gradually become complex, and simple organisms disappear. But we know that this is not the case, and those simple organisms still exist. So today, Lamarck’s theory of evolution is largely ignored.

Jean Baptiste Lamarck believed that all bodies had ‘subtle fluids’. These were weightless fluids pervading all space and bodies. Two good examples of eighteenth-century subtle fluids were electricity and heat. Lamarck believed that subtle fluids were responsible for both movement and change.

For example, he pointed out that snails have poor vision because feelers on their head acted as their eyes. According to him, the ancestors of snails did not have feelers. They groped about with their heads to find their way around. This groping sent subtle fluids to the front of the head, and the constant presence of moving subtle fluids eventually brought about the development of feelers, and these feelers were passed from generation to generation.

Charles Willson Peale

Charles Willson Peale founded a museum in Philadelphia, Pennsylvania, in 1786. It contained a collection of natural history specimens, portraits of admirable historical figures, and human artifacts from various countries. His purpose was to show the place of human beings as part of the animal kingdom. His most famous display, however, was the mastodon skeleton he obtained in 1801.

Measuring 3.35 meters high at the shoulder, and 4.5 meters from chin to rump, it was huge and strange and confusing. Was it a man or beast, an elephant, or some unknown animal? The fossil had been discovered in swampy ground and had been excavated with great difficulty. Man or beast, this ‘monstrous creature’, as it was called, would soon become celebrated as the unknown species or the ‘incognitum’.

Georges Cuvier

For many years, scientists refused to accept that some animals had become extinct. When remains were found that were unlike anything living at the time, they argued that they were unusual examples of living creatures, or that animals known only from fossils must still survive in some unexplored part of the world.

It was only at the end of the 18th century that the great French paleontologist and anatomist Georges Cuvier was able to demonstrate convincingly that extinctions were real. Cuvier was convinced that plants and animals of all types were created for their particular roles and places in the world’s environment and that they were unchanging throughout their existence.

According to him, catastrophic events in the course of history had killed off all members of some species, and their fossils would no longer be seen in the rocks. Subsequently, his evolution theory suggests, the old species were replaced by new ones that repopulated Earth.

Cuvier had an almost uncanny ability to reconstruct animals from only fragments of fossil remains. With elegant studies of the anatomy of large mammals such as elephants, Cuvier showed that fossil mammoths differed from any such creatures presently living. His many examples of fossils telling the stories of animals that lived and then disappeared were taken as incontrovertible proof of extinctions.

Hugh Miller

Hugh Miller was a 19th-century geologist. He put forward the theory that there had been several successive creations, and that each had been destroyed by a catastrophe. According to him, the Bible dealt with only the last creation. Miller’s theory of evolution explained the presence of fossils as being the remains of animals from an earlier creation.

Louis Agassiz

Louis Agassiz was a Professor of Zoology and Geology. He did landmark work on glacier activity and extinct fishes. He encouraged learning through direct observation of nature. Agassiz put forward the theory of a new catastrophe the Ice Age.

He believed that a sudden intense Ice Age gripped the Earth for ages, and wiped out all the existing animals and plants. His concept of the Great Ice Age brought him much fame, as he was able to present evidence in the field, especially the scratched surfaces of bedrock where rocks in the moving ice had gouged out deep marks.

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