Animal Life Cycles
Elementary School
Definition
The stages an animal passes through from birth or hatching to adulthood and reproduction. The stages differ among species—some animals undergo metamorphosis while others simply grow larger—but all cycles allow the species to continue.
Worked examples
A butterfly undergoes complete metamorphosis: egg → larva (caterpillar) → pupa (chrysalis) → adult butterfly.
Four distinct stages with dramatic body changes illustrate complete metamorphosis.
A grasshopper undergoes incomplete metamorphosis: egg → nymph → adult, with the nymph resembling a small wingless adult.
Three stages with gradual changes show incomplete metamorphosis; no pupal stage occurs.
A sea turtle hatches from an egg, grows continuously to adulthood, then returns to beaches to lay eggs—direct development.
No metamorphosis; the hatchling looks like a tiny adult and simply grows larger.
Common mistakes
- All animals go through metamorphosis during their life cycle → Only some animals undergo metamorphosis; many grow directly from young to adult Mammals, birds, and reptiles do not metamorphose—they grow larger but keep the same body plan.
- Incomplete metamorphosis means the animal skips one of the four stages → Incomplete metamorphosis has three stages (egg, nymph, adult) not four Complete metamorphosis has four stages; incomplete has three and no pupal stage.
- The life cycle ends when the animal becomes an adult → The life cycle includes reproduction, which produces the next generation Reproduction completes the cycle by creating offspring that start the stages again.
Where you'll use it next
You'll apply life cycles when studying ecosystems and food webs, comparing vertebrate and invertebrate reproduction, and exploring adaptations and evolution in biology.
See also
Metamorphic Life CyclesNon-metamorphic Life CyclesGrowth and ChangeParent-Offspring RelationsPlant Life CyclesAnimal Adaptations
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026