We start our second vertebrates lesson on amphibians after a small recap of the five classes of vertebrates.
We start the discussion of amphibians by describing the Life cycle of the frogs.
- Eggs: The mother amphibian lay soft, jelly like eggs in water, so that they won’t dry out. These eggs are really soft and they don’t have hard shell like the chickens egg. And the baby amphibians are born in water and they don’t resemble their mother and they are called tadpoles.
- Tadpoles: The tadpoles after hatching out of the egg stay sticking to the water plants as they can not see immediately. And the tadpoles breathe through gills like the fish. And they develop little mouth and begin to grow. They swim like fish with their fins and long tail.
- Froglet: At the end of tadpole stage, they grow legs, develop lungs and their gills disappear just in 24 hours. Their skin becomes thick, breath with their lungs, move with their limbs and come to land. This stage is called froglets. They lose their tail finally.
All amphibians go through these changes after they are born and we call this change metamorphosis. Thus they start their life in water and undergo development to live on land. They have life in water and land. Hence they are called amphibians ( amphi- both, bios – life). I use the following picture charts and cards from The Helpful Garden for explaining the life cycle of frog.
And on another time we describe the parts of the frog , adding few points day by day, as follows…..
Parts of the frog
- Head: The head of the amphibian is attached to the body with out neck. The amphibians eyes bulges from it’s head and it develops eyelids when they move to land. Their ears are nothing but an opening covered with skin called tympanum. They sense the vibrations and calls. They breathe through their nostrils and can detect odours. They have wide mouth with a bony jaw and sticky tongue to catch insects but no teeth to chew.
- Body: The body of the amphibians have moist skin that can absorb water and air directly. Thus they can breathe through their skin as well apart from the lungs. Amphibians are cold blooded similar to the fish.
- Limbs: They have limbs to help them move. The limbs in the front are short and called forelegs. The limbs at the back are called Hind legs. Hind legs are long and strong and they are used to swim and leap. Their feet are webbed to help in swimming. Webs are the membrane found between the toes that act like a paddle while swimming. And they have claws for digging.
Parts of the frog is explained with the puzzle and nomenclature cards (from Waseca Biomes).
- Salamanders have lizard like appearance
- They also undergo metamorphosis like frog but their tadpoles head doesn’t grow big and their tails stay long in the adult period as well.
- They eat fish, worm and insects.
- They are nocturnal.
- They are leg less, burrowing worm like amphibians.
- They are found in moist soil.
We show various frogs, toads, salamanders and caecilians of various continents, to the children with the picture cards in our amphibians folder that I have prepared from thehelpfulgarden website.
And to add more fun to the lessons, we do art and crafts on the concept with the children.
And that’s our amphibians lesson.