Metamorphosis in frog

It is an 8th class topic from chapter reproduction in animals.

1. CONTENT : Introduction Types of development Defining metamorphosis Life cycle of a frog Video showing frog’s life cycle Role of hormones in metamorphosis Worksheet Activity for kids

2. LEARNING OUTCOMES : Students will be able to : Define metamorphosis. Differentiate between direct and indirect development. List the changes that take place when a tadpole changes into an adult frog. Develop the skill of drawing using methods like clay modelling . Explain the role of iodine in the process of metamorphosis.

3. INTRODUCTION There are two different types of animals depending on whether female gives birth to young ones or lay eggs i.e : OVIPAROUS VIVIPAROUS All young ones grow to form adults regardless of whether they have hatched from an egg or are born directly .

4. TYPES OF DEVELOPMENT Different organisms show different development pattern depending on whether the young one at birth is miniature version of adult form or not. There are two types of development shown by the organisms: Direct development Indirect development

5. DIRECT DEVELOPMENT Young one at birth is a miniature version of the adult form. Example : birds and mammals

6. INDIRECT DEVELOPMENT Young ones are initially very different from their adults. Also there are number of features in adult form which are not present in larval stages or in initial stages. Example : Tadpole looks very different from a frog. A caterpillar looks very different from a butterfly.

7. STAGES OF A SILKWORM

8. METAMORPHOSIS DEFINITION : A radical change in structure and habit of an animal (as in case of butterfly or a frog) during its life cycle is termed as metamorphosis. OR Transformation of a young one into an adult through number of drastic changes in its form and structure.

9. JOURNEY FROM A YOUNG ONE TO ADULT

10. Learning through video

11. KEYPOINTS : Eggs are laid in water. Tadpole emerges from the egg and swims freely in water. Tadpole has gills, a tail and a small circular mouth. Tadpole grows until it begins metamorphosis. Metamorphosis is marked by the development of hind legs followed by the front legs.

12. Lungs develop and tadpole begins to swim to the surface of water to breathe. Intestine shortens to adapt the animal to a carnivorous diet. T ail gets absorbed by the body during the last stages of metamorphosis. This way a tailed tadpole changes into a tail-less frog.

13. HORMONES AND METAMORPHOSIS Thyroxine produced by thyroid gland of frog is essential to carry out the process of metamorphosis in frogs. Iodine is needed for the production of thyroxine and is present in water in which tadpoles are growing . In insects also, hormones control metamorphosis and is produced by some cells present their brain and glands located elsewhere in their body.

14. WORKSHEET Define metamorphosis. Differentiate between direct and indirect development. List three changes that take place when a tadpole changes into a frog. What will happen to a tadpole if iodine is deficient in the water where tadpoles are growing? A tadpole is different from frog. How ?

15. SELF ASSESSMENT USING GOOGLE FORMS

16. ART INTEGRATION ACTIVITY Draw the life cycle of a dragon or a frog or any other organism using any of the following technique/ method: 1. clay modelling art 2. mosaic art NOTE: You can use A4 size sheet/ paper plates/ cardboard for the activity. RUBRICS: Creativity: 2 marks Presentation: 2 marks Content : 1 marks

17. SAMPLES