Metazoa vs. Eumetazoa — What's the Difference?
By Tayyaba Rehman & Maham Liaqat — Updated on April 18, 2024
Metazoa refers to all multicellular animals, encompassing a vast diversity from sponges to humans, while Eumetazoa includes all metazoans except sponges, characterized by true tissues.
Difference Between Metazoa and Eumetazoa
Table of Contents
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Key Differences
Metazoa encompasses all animals that are multicellular, from the simplest sponges to complex vertebrates, whereas Eumetazoa excludes the parazoan sponges, highlighting animals with organized tissues and organs.
Metazoans exhibit a variety of body plans and levels of complexity, whereas Eumetazoans specifically demonstrate true tissues and symmetry, which are absent in simpler metazoans like sponges.
In terms of embryonic development, all Metazoa start from a single cell that divides and differentiates, while Eumetazoa specifically undergoes gastrulation—a key developmental stage that forms distinct germ layers.
Metazoa’s classification includes both Eumetazoa and more basal groups like Porifera (sponges), while Eumetazoa groups together more evolutionarily advanced animals, excluding Porifera.
Metazoan phyla show a range of sensory and nervous systems, while Eumetazoa generally have more complex nervous and sensory structures due to their organized tissues.
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Comparison Chart
Definition
All multicellular animals
Multicellular animals with true tissues
Includes
Sponges, jellyfish, worms, insects, mammals
Jellyfish, worms, insects, mammals (excludes sponges)
Developmental features
Multicellular growth, may lack organized tissues
Gastrulation, organized tissues and organs
Complexity
Ranges from very simple to complex
Generally more complex than basal metazoans
Example phyla
Porifera, Cnidaria, Chordata
Cnidaria, Arthropoda, Chordata
Compare with Definitions
Metazoa
Multicellular animals.
A sponge is considered a metazoan due to its multicellular nature.
Eumetazoa
Organized germ layers.
During development, eumetazoans form distinct germ layers unlike some simpler animals.
Metazoa
Includes Porifera.
Unlike eumetazoans, metazoans include the Porifera phylum.
Eumetazoa
Multicellular animals with tissues.
Jellyfish are considered eumetazoans because they have organized tissues.
Metazoa
Includes all animal kingdoms.
From simple sponges to complex mammals, all are metazoans.
Eumetazoa
Higher complexity than sponges.
Eumetazoans generally possess a more complex structure than sponges.
Metazoa
Diverse body plans.
Metazoans exhibit body plans ranging from radial to bilateral symmetry.
Eumetazoa
Excludes sponges.
Eumetazoa consists of all multicellular animals except for the sponges.
Metazoa
Varies in complexity.
Metazoan complexity varies from sponges without tissues to humans with advanced organ systems.
Eumetazoa
Symmetry in body plan.
Eumetazoans typically display either radial or bilateral symmetry.
Metazoa
(zoology) The multicellular eukaryotes of the kingdom Metazoa considered collectively.
Eumetazoa
Eumetazoa (Greek: εὖ [eu], well + μετά [metá], after + ζῷον [zóon], animal), also known as Diploblasts, Epitheliozoa, or Histozoa, are a proposed basal animal clade as a sister group of the Porifera. The basal Eumetazoan clades are the Ctenophora and the ParaHoxozoa.
Metazoa
Those animals in which the protoplasmic mass, constituting the egg, is converted into a multitude of cells, which are metamorphosed into the tissues of the body. A central cavity is commonly developed, and the cells around it are at first arranged in two layers, - the ectoderm and endoderm. The group comprises nearly all animals except the Protozoa.
Metazoa
Multicellular animals having cells differentiated into tissues and organs and usually a digestive cavity and nervous system
Common Curiosities
How do Metazoa differ in complexity?
Metazoan complexity ranges from the simple, tissue-less sponges to complex organisms with organs.
What are Eumetazoa?
Eumetazoa are multicellular animals characterized by having true tissues and excluding sponges.
Can you give examples of Metazoa?
Examples include sponges, jellyfish, worms, insects, and mammals.
What defines a Metazoa?
Metazoa are defined as all multicellular animals, including very simple forms like sponges.
How does the nervous system vary between Metazoa and Eumetazoa?
Eumetazoans typically have a more complex nervous system due to their organized tissue structures.
What is a key developmental feature of Eumetazoa?
A key feature of Eumetazoa is gastrulation, a process that forms distinct germ layers.
What differentiates Eumetazoa from other multicellular animals?
Eumetazoa are differentiated by organized tissues and exclusion of the most primitive multicellular animals, sponges.
Why are sponges not considered Eumetazoa?
Sponges lack true tissues and organs, which are defining characteristics of Eumetazoa.
What are the evolutionary implications of being a Eumetazoan?
Being a Eumetazoan typically indicates a more advanced evolutionary stage with specialized adaptations.
What is the significance of tissues in Eumetazoa?
Tissues allow Eumetazoa to have more complex and specialized functions than simpler metazoans.
Are all animals either Metazoa or Eumetazoa?
Yes, all animals are classified as either Metazoa or Eumetazoa, with Metazoa being the broader category.
What are the reproductive differences between Metazoa and Eumetazoa?
Both Metazoa and Eumetazoa exhibit a variety of reproductive strategies, but Eumetazoa often have more complex reproductive systems due to their structured bodies.
What is the simplest form of Metazoa?
The simplest form of Metazoa are the Porifera, or sponges, which lack organized tissues.
Do all Eumetazoa have bilateral symmetry?
Most Eumetazoa exhibit bilateral symmetry, though some, like jellyfish, display radial symmetry.
How do tissue layers affect Eumetazoan development?
Tissue layers in Eumetazoa lead to the formation of complex organs and systems during embryonic development.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Maham Liaqat
