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Parazoa
Fossil range: Ediacaran - Recent
A sponge
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Parazoa
Grant & Todd, 1838
Phyla

The Parazoa are an ancestral subkingdom of animals, literally translated as "beside the animals".

Contents

Description

Parazoans differ from their choanoflagellate ancestors in that they are macroscopic and have differentiated cells, but unlike "true animals" (Eumetazoa), they do not have tissues. The only surviving parazoans are the sponges, which belong to the phylum Porifera, and one surviving species (Trichoplax adhaerens) in the phylum Placozoa.

Parazoa display no body symmetry (are asymmetrical); all other animal groups display some sort of symmetry. There are currently 5000 species, 150 of which are freshwater. Larvae are planktonic and adults are sessile.

Cladistics

The Parazoa-Eumetazoa split has been estimated at 940 million years ago.[1]

The parazoa group is now considered paraphyletic.[2] It is not included in most modern cladistic analyses. When referenced, it is sometimes considered an equivalent to Porifera.[3]

Some authors include Placozoa,[4] a phylum that consists of only one species, Trichoplax adhaerens, in the division, but they are also sometimes placed in the subkingdom Agnotozoa.

References

External links

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Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

English

Etymology

Greek ?

Proper noun

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Wikipedia

Parazoa

  1. a taxonomic subkingdom, within kingdom Animalia - the sponges

Related terms

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Wikispecies


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Parazoa
Phyla: Porifera

Name

Parazoa

References

  • Gordon, D.P. (ed.) 2009: New Zealand inventory of biodiversity. Volume 1. Kingdom Animalia. Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch, New Zealand.
  • Leys, S.P.; Eerkes-Medrano, D. 2005: Gastrulation in calcareous sponges: in search of Haeckel’s Gastraea. Integrative & comparative biology, 45: 342–351. PDF

Vernacular names

Català: Porífer o Esponges
Deutsch: Gewebelose
Ελληνικά: Παράζωα
English: parazoans
Español: Parazoos
Français: Parazoaires
한국어: 측생동물아계
עברית: ספוגיים
Magyar: Álszövetes állatok
Македонски: Бесткивни животни
日本語: 側生動物亜界
‪Norsk (bokmål)‬: Svamper
Polski: Beztkankowce
Português: Parazoários
Română: Bureţi de mare
Русский: Паразои
Suomi: Sienieläinmäiset
Türkçe: Gerçek dokusu olmayan hayvanlar
中文: 侧生动物亚界
Wikimedia Commons For more multimedia, look at Parazoa on Wikimedia Commons.

Simple English

Parazoa
Scientific classification
Kingdom: Animalia
Division: Parazoa
phylum

Porifera

The Parazoa are an ancestral subkingdom of animals, literally translated as "beside the animals". Parazoans differ from their choanoflagellate ancestors in that they are macroscopic and have differentiated cells, but unlike "true animals" (Eumetazoa), they do not have tissues. The only surviving parazoans are the sponges, which belong to the phylum Porifera. Some include Placozoa, a phylum that consists of only one species, Trichoplax adhaerens, in the division, but they are also sometimes placed in the subkingdom Agnotozoa.


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