What is Metamorphosis?


Metamorphosis is the process in which an animal transforms from one immature form to a different adult form.


Bimodal life cycle
Aquatic Egg and Larva
Terrestrial Adult

There is an abrupt transformation from a gilled aquatic form to an air breathing terrestrial form.


  • Some amphibians like the Slimy Salamander have direct development - larvae stay within the egg and tiny adults hatch out
  • Some amphibians like the Axolotl are neotenic - the adults look like the larvae
  • The Eastern Newt has a fourth stage, metamorphosing twice!
    Aquatic Egg - Larva - Terrestrial Eft - Aquatic Adult


Complete Metamorphosis

  • There are 4 distinct life stages.
  • During the pupal stage, the insect does not eat.
  • Butterflies, Beetles, Bees and Ants have Complete Metamorphosis.


Incomplete or Simple Metamorphosis

  • There are 3 distinct life stages - no pupal stage.
  • Nymphs often look like small, wingless adults.
  • Nymphs go through gradual changes, molting several times.
  • Dragonflies, have Incomplete Metamorphosis with an aquatic naiad.
  • Grasshoppers & Mantids have Gradual Metamorphosis, (Paurometabolous) - the nymphs live in the same habitat as the adults.


Complex life cycle
requires another species.
Internal Egg
Parasitic Larva (glochidia)
Juvenile Mussel

  • The glochidia of most mussels attach to fish, either to the gills or fins. 
  • They form cysts inside which then transform to juvenile mussels.  
  • After transformation, they drop off their host.