Life Cycles: Butterfly and Frog - First Grade Science
While many baby animals, like kittens and puppies, look like tiny versions of their adult parents when born, some creatures undergo an astounding biological transformation called metamorphosis. The word metamorphosis means "a complete change of body shape." Two of the most famous and captivating examples of metamorphosis in nature are the life cycle of the butterfly and the life cycle of the frog. Both animals begin life as tiny eggs and pass through dramatic stages before emerging as magnificent adults.
The Butterfly Life Cycle: Complete Metamorphosis
A butterfly undergoes complete metamorphosis, which consists of four distinct stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly.
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| THE 4 STAGES OF A BUTTERFLY |
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| [ STAGE 1: EGG ] |
| Tiny egg laid on a leaf. |
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| [ STAGE 2: LARVA / CATERPILLAR ] |
| Eats leaves hungrily and molts. |
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| v |
| [ STAGE 3: PUPA / CHRYSALIS ] |
| Rests inside shell; body rebuilds! |
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| v |
| [ STAGE 4: ADULT BUTTERFLY ] |
| Wings expand; drinks nectar; lays eggs. |
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Stage 1: The Egg
A female butterfly carefully glues tiny round or oval eggs to the underside of specific host plant leaves. She chooses leaves that will provide the exact food her babies need to eat upon hatching.
Stage 2: The Larva (Caterpillar)
When the egg hatches, a tiny worm-like caterpillar emerges. The caterpillar's only mission is to eat! It munches green leaves continuously, growing so quickly that its skin becomes too tight. It sheds its outer skin multiple times in a process called molting.
Stage 3: The Pupa (Chrysalis)
Once the caterpillar has stored plenty of energy, it hangs upside down from a twig in a J-shape and forms a smooth, hardened shell called a chrysalis. (Moths spin silk cocoons, but butterflies form a chrysalis). Inside this protective chamber, the caterpillar's old body dissolves and completely reorganizes into long legs, antenna, compound eyes, and brilliant wings!
Stage 4: The Adult Butterfly
The chrysalis splits open and a magnificent butterfly steps out. Its wings start out small, wet, and crumpled. The butterfly pumps warm fluid through the wing veins until they expand to full size and dry in the sun. Soon, it flutters gracefully into the air to sip flower nectar and begin the cycle again.
The Frog Life Cycle: From Water to Land
Frogs are amphibians, meaning they live a double life: part of their lives swimming in freshwater and part living on damp land.
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| THE 4 STAGES OF A FROG |
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| [ STAGE 1: FROG EGG ] |
| Jelly clumps laid in pond water. |
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| [ STAGE 2: TADPOLE ] |
| Swims with tail; breathes with gills. |
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| [ STAGE 3: FROGLET ] |
| Grows back and front legs; loses tail. |
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| v |
| [ STAGE 4: ADULT FROG ] |
| Breathes with lungs; leaps on land! |
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Stage 1: The Egg Mass
Mother frogs lay hundreds or thousands of soft, clear jelly-like eggs in calm pond waters. The jelly protects the black embryos inside and keeps them warm and moist.
Stage 2: The Tadpole (Polliwog)
When the eggs hatch, swimming creatures called tadpoles emerge. A tadpole looks like a small fish with a round head and a long swimming tail. It lives entirely underwater, swimming through algae and breathing oxygen through feathery gills.
Stage 3: The Froglet
Over several weeks, incredible changes take place. First, two long back legs sprout near the base of the tail. Next, front legs push out. Inside its body, lungs begin to develop while the gills disappear. As the young froglet prepares for life on land, its long swimming tail is slowly absorbed by its body for nutrition.
Stage 4: The Adult Frog
With lungs to breathe air, strong legs for hopping, and no tail left, the adult frog hops out of the water onto lily pads and pond banks. It catches insects with its lightning-fast sticky tongue and swims back into the water to lay eggs when breeding season arrives.
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| COMPARING BUTTERFLY AND FROG |
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| FEATURE BUTTERFLY METAMORPHOSIS FROG METAMORPHOSIS |
| Egg Location Under host plant leaves Floating in pond water |
| Young Stage Crawling caterpillar Swimming tadpole |
| Breathing (Young) Tiny air holes (spiracles)Underwater gills |
| Adult Movement Flies with 4 wings Hops with 4 legs |
| Adult Habitat Gardens, meadows, woods Ponds, wetlands, woods |
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Chapter Review Exercises
Question 1: What is metamorphosis, and why are butterflies and frogs considered examples of it?
Question 2: List the four stages of a butterfly's life cycle in chronological order.
Question 3: How does a young tadpole breathe and move differently than a fully grown adult frog?
Question 4: What is the difference between a butterfly's chrysalis and a moth's cocoon?
Solutions and Explanations
Solution 1: Metamorphosis is a biological process where an animal undergoes a dramatic, total change in its body shape and structure as it matures from baby to adult. Butterflies and frogs are prime examples because their young (caterpillars and tadpoles) look, breathe, and act completely different from their adult forms.
Solution 2: The four stages of the butterfly life cycle are Stage 1: Egg, Stage 2: Larva (caterpillar), Stage 3: Pupa (chrysalis), and Stage 4: Adult butterfly.
Solution 3: A young tadpole lives completely underwater, swims using a flexible finned tail, and breathes through gills. A mature adult frog hops on land using four muscular legs, swims with webbed feet, and breathes air using lungs and moist skin.
Solution 4: A butterfly forms a chrysalis, which is a smooth, hardened outer shell formed from the caterpillar's own outer skin. A moth spins a cocoon, which is a soft, protective silk sleeping bag woven from silk threads produced by the caterpillar before it pupates.