Animal Life Cycles

Animals that Grow Up (Simple Life Cycle):

Most animals including fish, mammals, reptiles and birds have very simple life cycles:

• they are born (either alive from their mother or hatched from eggs)
• they grow up

These animals have three stages -- before birth, young and adult.  The young are typically similar to the parent, just smaller.  The young slowly "grow" to become adults.

Amphibians:

Amphibians, like frogs and newts, have a slightly more complicated life cycle.  They undergo a metamorphosis (a big change):

• they are born (either alive from their mother or hatched from eggs)
• they spend their childhood under water, breathing with gills
• they grow into adults and move to the land, breathing with lungs

Animals that Undergo a Complete Metamorphosis:

Insects

These insects have four stages in their life cycle:

• egg:   unborn stage.
• larva:   young stage -- this is when most of the feeding is done.
          (they usually look like worms)
• pupa:  inactive (no feeding) stage between larva and adult stages.
          (usually well camouflaged)
• adult:   final, breeding stage.
           (they usually grow wings)

Animals that go through a complete metamorphosis are what my daughter Kaitlyn calls "Wow!" animals -- they go to bed looking one way and wake up a completely different creature.  Wow!

Animals that Undergo an Incomplete Metamorphosis:

About 10% of insects go through an incomplete metamorphosis.  They do not have a pupal form -- these include dragonflies, grasshoppers and cockroaches.

These insects have three stages in their life cycle:

• egg:   unborn stage.
• nymph:   young stage -- this is when most of the feeding is done.
• adult:   final, breeding stage - including wings.

Worksheets: