Metamorphosis (Encyclopedia of Science)
Metamorphosis is a series of changes through which an organism goes in developing from an early immature stage to an adult. Most people are familiar with the process, for example, by which a butterfly or moth emerges from a chrysalis (cocoon) in its adult form or a frog or toad passes through its tadpole stage.
Metamorphosis is perhaps best known among insects and amphibians (organisms such as frogs, toads, and salamanders that can live either on land or in the water). However, the process of metamorphosis has been observed in at least 17 phyla (a primary division of the animal kingdom), including Porifera (sponges), Cnidaria (jellyfish and others), Platyhelminthes (flat worms), Mollusca (mollusks), Annelida (segmented worms), Arthropoda (insects and others), Echinodermata (sea urchins and others), and Chordata (vertebrates and others).
In addition, although the term metamorphosis is generally not applied to plants, many plants do have a developmental life cyclealled the alternation of generationshich is also characterized by a dramatic change in overall body pattern.
Forms of metamorphosis
Metamorphosis in an organism is generally classified as complete or incomplete. Complete metamorphosis involves four stages: egg, larva, pupa, and adult. Consider the sequence of these stages in an insect. After a fertilized egg is...
(The entire section is 576 words.)
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