Definition

1. Noun:
   • A multicellular animal organism: A "metazoan" is any animal belonging to the subkingdom Metazoa. This group includes all animals with bodies composed of multiple, differentiated cells organized into tissues and organs, excluding single-celled protozoans and simple multicellular sponges (Porifera) which lack true tissues.

Usage Examples

• Noun:
  • The evolution of the first metazoan marked a significant step in the history of life on Earth.
  • Insects, fish, birds, and mammals are all examples of complex metazoans.
  • The study focused on the developmental biology of various marine metazoans.

Advanced Usage

• In scientific classification: The term is used taxonomically to distinguish complex multicellular animals from other life forms.
  • The phylogenetic tree shows the divergence of metazoan lineages from a common ancestor.
• As an adjective (less common): While primarily a noun, "metazoan" can be used attributively to describe characteristics of these animals.
  • The researcher studied metazoan body plans and their genetic basis.

Variants and Related Words

• Metazoa (n, plural): The taxonomic subkingdom name itself.
  • The subkingdom Metazoa encompasses a vast diversity of life forms.
• Metazoic (adj): Pertaining to or characteristic of metazoans.
  • The fossil record provides evidence of early metazoic life.

Synonyms

• Multicellular animal: A descriptive synonym emphasizing the cellular complexity.
• Eumetazoan: A more specific term often used to refer to metazoans with true tissues (i.e., excluding sponges). Note: In some contexts, "metazoan" and "eumetazoan" are used interchangeably, but technically "eumetazoan" is a subgroup.

Related Phrases / Terms

• Metazoan parasite: A parasitic organism that is a multicellular animal.
  • The disease is caused by a metazoan parasite transmitted by mosquitoes.
• Metazoan evolution: The study of the evolutionary history of multicellular animals.
  • Her research contributes to our understanding of key events in metazoan evolution.

Noun

1. any animal of the subkingdom Metazoa; all animals except protozoans and sponges