609752_simulated_frog_dissection_kit by Meenakshi Bhatia

INSIDE THE BOX

ABOUT THE KIT All animals are incredible things. To understand how an animal works we need to study its body, inside and outside, looking at how all the different body parts fit together and finding out what the relationships are between them. When people cut a dead animal's body apart in a scientific way we say that they are “dissecting” it.

Frog Body parts separated

Your frog model can show you exactly what is going on inside a frog. You can see how all the organs and body parts relate to each other. And you can do it all without taking a real frog apart!

Frog Morphology

SIMULATED FROG DISSECTION KIT

LET’S KNOW ABOUT FROG! Frogs are amphibians. The word “amphibian” comes from Greek – “amphi” meaning both, and “bios” meaning life, which refers to the fact that amphibians can live both on land and in water. There are around 6,000 different types of frog in the world, but all follow the same cycle of life. They all begin their lives in or around water as eggs that hatch into tiny tadpoles. At first a tadpole has no proper shape, and no tail. Tadpoles stay in the water all the time, so like fish they breathe through gills. They feed only on plants and as they grow their head develops a big round mouth and they get a flat tail. They look a lot more like fish than frogs! Tadpoles then undergo an incredible transformation called metamorphosis (again from Greek – “meta” meaning change, and “morphe” meaning form). This is where they develop lungs and legs, and begin to eat insects and other small animals. When a frog is fully developed it loses its tail, and will usually live somewhere near fresh water. Frogs have delicate skin, and if a frog dries out it will soon die so it is important that frogs live somewhere damp.

Simulated Frog dissection Kit

SIMULATED FROG DISSECTION KIT

FROG LIFECYCLE Here is a step by step life cycle of a frog: 1. The life cycle of a frog starts in water where a female lays 500 to 5000 eggs when clasped by a male. These eggs are fertilized by males as they are shed, over the course of about 10 minutes. 2. Each egg has 3 jelly coats which swell with water to enclose it thus protecting it from other predators. 3. Each egg undergoes 1st cleavage in about 3-12 hours, depending on temperatures. The successive cleavages occur more rapidly thereafter. 4. At 4 days the embryo has a tail bud. It also shows early muscular movement and subsists on the yolk packet in its gut. 5. Egg hatches at 6 days as tadpole with external gills. A tadpole clings to submerged vegetation with its sucker. 6. Tadpole begins feeding on algae at 7 days. 7. By 11 days a skin fold grows over external gill leaving a pore or a spiracle on the left side for exit of water. 8. By 75+ days internal gills are replaced by lungs. The hind limbs appear first then the fore limbs. 9. The tail shortens and metamorphosis stage is complete by 90+ days. The tadpole is now transformed to a juvenile frog. It has functional legs and remains juvenile for 1-2 years. 10. It becomes sexually mature frog at 3 years

Frog Spawn

2 days old tadpole

2 weeks old tadpole

8 weeks old tadpole

10 weeks old tadpole

Adult Frog

SIMULATED FROG DISSECTION KIT

FROG BODY PARTS Your ‘Iken Joy Frog dissection kit’ comes with eleven removable parts – the four legs, part of the mouth, and six parts from inside the chest of the frog. Inside the chest of the frog are some important body parts. We call these “organs”. If you were dissecting a real frog, you would have to turn it so it was lying on its back. Then to get to these organs you would have to cut open the chest of the frog. On dissecting a frog we find 4 layers with following organs

SIMULATED FROG DISSECTION KIT

Layer 1

Layer 2

Layer 3

Layer 4

Liver Heart

Gall bladder Stomach Small intestines

Lungs Pancreas Mesentery

Male frog Spleen Kidneys Testes Female frog Spleen kidneys Ovaries Oviducts

SIMULATED FROG DISSECTION KIT

FROG BODY PARTS Heart The Heart is the organ that pumps blood through the frog's body and it is split into three parts or â&#x20AC;&#x153;chambersâ&#x20AC;? - the left atrium, the right atrium and the ventricle. It is the small triangular shaped organ between the front legs and anterior to the liver. Like in other animals, the frog heart's job is to pump blood to the lungs where the blood becomes rich in oxygen. This oxygen rich blood then flows back to the heart where it is pumped out again, this time around the body through the arteries where the oxygen is used up. Finally, this oxygen poor blood returns to the heart through the veins, where the circle starts again and it is sent to the lungs. A frog's heart has just 3 chambers, while a human heart has 4. The frogs' heart has a special design that means that oxygen rich and oxygen poor blood cannot mix, even though they meet in the same chamber. Why is the circulatory system "closed" for business? The flow of blood to the tissues in your body is called the circulatory system. It provides the oxygen and nutrients that tissues need to function. The circulatory system's main components are veins, arteries, capillaries, and the heart. In a frog, the blood goes to the lungs and skin to replenish its oxygen (In a human, it's just the lungs). This is a "closed system" because the blood stays inside the system's components.

Heart

Intestine

SIMULATED FROG DISSECTION KIT

FROG BODY PARTS Liver Have you ever thought of how does the body clean itself from inside? The liver is the housekeeper for frog and human bodies. It is a large, brownish colored organ covering most of the body cavity. It extracts impurities (toxins and wastes) from the blood so they can be eliminated from the body. It also converts food into nutrients for the body by creating Bile, an important chemical that digests food. Attached to the liver is a smaller green â&#x20AC;&#x153;ballâ&#x20AC;?. This is the gall bladder. The gall bladder is where this liquid is stored. Stomach Food does begin to get broken down in the stomach, but most digestion takes place later when the food goes from the stomach to the intestines.

Mouth

Lungs Kidney Liver Bladder Stomach

The Intestines Anything that passes through the frog's stomach will first go through the small intestine. This is where digestion really gets underway. Food here is broken down in a very similar way to how it takes place in mammals. Enzymes begin to break the food down into nutrients that the body can absorb and use. The food will pass through into the large intestine and then once all the nutrients have been removed the waste passes out of the body.

Legs

SIMULATED FROG DISSECTION KIT

FROG BODY PARTS Lung

The Kidneys

Once a tadpole begins to change into a frog it starts to develop lungs. The lungs are like two little sacks located high up above the heart. Just like when humans breathe, air enters the body through the frog's nose or mouth. It then passes through the windpipe, and into the lungs. Humans use their chest muscles and diaphragm to breathe, but frogs don't have ribs or a diaphragm, and it doesn't use its chest muscles for breathing. You have probably seen that when a frog sits still its neck seems to blow in and out like a small balloon. This puffing in and out is what forces air in and out of the lungs. The frog's heart and lungs work in a similar way to those in mammals. The oxygen comes into the blood by breathing air through the nose or mouth. But frogs are special! They can also breathe underwater. Frogs have very soft, thin and moist skin with lots of blood vessels. When a frog goes underwater it can get oxygen directly into its blood stream through these blood vessels as its skin is so thin. A frog can actually breathe through its skin!

The kidneys are where the frog's blood gets cleaned. All the waste substances in the blood are filtered out in the kidneys and then passed out of the frog's body. The kidneys also balance lots of other things in the blood such as the levels of water and minerals.

SIMULATED FROG DISSECTION KIT

Bladder The bladder is a membranous sac that serves as the receptacle for liquid waste before it is passed through the cloaca.

Fat bodies The remaining two removable parts of your model are both fat bodies. Like in humans, when a frog eats more food than it needs, the energy is stored in fat. This energy can then be used when the frog has trouble finding food. Some frogs can go a very long time without food (some frogs can go for over a month) and in these times they live on the energy supplies they have stored as fat.

SIMULATED FROG DISSECTION KIT

FROG BODY PARTS

FROG IN DANGER

The Legs

All amphibians are very sensitive to changes in their surroundings because of their thin and sensitive skin. They are especially vulnerable to pollution and temperature changes. The biggest ever study of the world's frogs was published in 2004. The scientists that took part in the study found that frogs are having a very difficult time. They found that frogs were disappearing from lots of environments because of pollution and also environmental changes. The study found that up to a third of the world's frogs are threatened with extinction. There are around 6,000 different types of frogs in the world, and around 2,000 types are endangered. This is because they are far more sensitive to pollution and environmental changes than nearly all other animals. Today there is more pollution and there are more toxic chemicals in the environment than ever before, and the frogs feel the effects of these far more than humans do. Skin diseases in frogs are also on the increase, and humans are moving more and more into places where frogs live. This all adds up to a big problem for the world's frogs. Now that you know what is going on inside of a frog, have fun exploring.

You can see that the frog's back legs are much larger than its front legs. The back legs have much more muscle (the pink area) than the front legs. A frog usually moves around on land by jumping or hopping. In the water it uses its back legs to paddle through the water. To jump, hop and swim the frog needs big, strong muscles in its back legs. You can also see that the “toes” on the frog's back legs have flaps of skin, called “webs”, between them. These help the frog when it is swimming. Inside all of the legs you can see the bone (the small white area in the middle of each leg) an artery (the red circle that carries blood to the muscles) and a vein (the blue circle that carries blood back to the heart).

The Mouth Just like in humans the mouth is where a frog's food enters its body. A frog does have teeth, but they are very small and are not much use for catching or chewing food – you can see the small white line in the top of the mouth. Most frogs catch their food (usually passing insects) using special sticky tongues that curl up in their mouths. They flick out their tongues out very quickly and drag what they catch back into their mouths. The food is quickly swallowed and passes down the frog's throat into its stomach. This means that the food will usually end up in the frog's stomach in one piece.

SIMULATED FROG DISSECTION KIT

QUIZ

Hope you have thoroughly enjoyed learning from this series of science toy from iken joy and also have a good idea about human body and its various parts. Now check your learning from the kit through this multiple choice quizzes.

Ÿ5. Tadpoles then undergo an incredible transformation called ŸMetamorphosis ŸAmphibiotic ŸConversis ŸHatching

1. When you cut a dead animal's body apart in a scientific way you call it ŸMetamorphosis ŸDissection ŸChopping ŸDialysis

6. Tadpole begins feeding on algae in ŸA week ŸA day ŸA year ŸA minute

2. The word “amphibian” means ŸCan live on plants ŸCan live both on land and in water ŸCan fly for food ŸGrasshoppers

7. The frog heart's job is to ŸDigest food ŸPump blood ŸTake oxygen ŸNone of the above

3. There are around how many different types of frog in the world? Ÿ1000 Ÿ6000 Ÿ20000 Ÿ100000

8. Attached to the liver is a smaller green “ball” called the ŸKidney ŸPancreases ŸIntestine ŸGall bladder

4. Tadpoles breathe through ŸNose ŸGills ŸPalm ŸFins

SIMULATED FROG DISSECTION KIT

REFERENCES

NOTES

If you want to explore more on frog anatomy and watch multimedia presentation on this topic, here are some references. 1. General information about amphibians http://www.scienceclarified.com/Al-As/Amphibians.html 2. Detailed frog anatomy http://frog.edschool.virginia.edu/Frog2/Dissection/Organs

SIMULATED FROG DISSECTION KIT

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