Editing Sponge (section)

=== Classes ===

Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have now shown that the [[Homoscleromorpha]], a group thought to belong to the [[Demospongiae]], has a [[phylogenetics|genetic relationship]] well separated from other sponge classes.<ref name="Bergquist_1978"/>{{rp|153–154}} Therefore, they have recently been recognized as the fourth class of sponges.<ref name="Gazave2010">{{cite journal |last1=Gazave |first1=Eve |last2=Lapébie |first2=Pascal |last3=Renard |first3=Emmanuelle |last4=Vacelet |first4=Jean |last5=Rocher |first5=Caroline |last6=Ereskovsky |first6=Alexander V. |last7=Lavrov |first7=Dennis V. |last8=Borchiellini |first8=Carole |title=Molecular phylogeny restores the supra-generic subdivision of homoscleromorph sponges (Porifera, Homoscleromorpha) |journal=PLOS ONE |volume=5 |issue=12 |pages=e14290 |date=December 2010 |pmid=21179486 |pmc=3001884 |doi=10.1371/journal.pone.0014290 |bibcode=2010PLoSO...514290G |doi-access=free }}</ref><ref name="Gazave_2012">{{cite journal |last1=Gazave |first1=Eve |last2=Lapébie |first2=Pascal |last3=Ereskovsky |first3=Alexander V. |last4=Vacelet |first4=Jean |last5=Renard |first5=Emmanuelle |last6=Cárdenas |first6=Paco |last7=Borchiellini |first7=Carole |date=May 2012 |title=No longer Demospongiae: Homoscleromorpha formal nomination as a fourth class of Porifera |url=https://hal.archives-ouvertes.fr/hal-01456632/file/Gazave%20et_2012-%20class.pdf |journal=Hydrobiologia |volume=687 |issue=1 |pages=3–10 |doi=10.1007/s10750-011-0842-x |bibcode=2012HyBio.687....3G |s2cid=14468684 |access-date=2019-08-01 |archive-date=2019-08-01 |archive-url=https://web.archive.org/web/20190801192211/https://hal.archives-ouvertes.fr/hal-01456632/file/Gazave%2520et_2012-%2520class.pdf |url-status=live }}</ref>

<!-- [[File:Sponge in papua new guinea.jpg|thumb|A sponge in [[Papua New Guinea]]]] -->
Sponges are divided into [[Class (biology)|classes]] mainly according to the composition of their [[skeleton]]s:<ref name="Bergquist_1998"/> These are arranged in evolutionary order as shown below in ascending order of their evolution from top to bottom:

:{|class="wikitable"
! [[Class (biology)|Class]] !! Type of cells<ref name="Bergquist_1998">{{cite book |last=Bergquist |first=P.R. |year= 1998 |chapter=Porifera |pages=10–27 |editor=Anderson, D.T. |title=Invertebrate Zoology |publisher=Oxford University Press |isbn=978-0-19-551368-4}}</ref> !! [[Sponge spicule|Spicules]]<ref name="Bergquist_1998"/> !! [[Spongin]] fibers<ref name="Bergquist_1998"/> !! Massive exoskeleton<ref name="Bergquist_2001"/> !! Body form<ref name="Bergquist_1998"/>
|-
! [[Hexactinellida]]
|Always mostly [[syncytia]] ||[[Silica]]<br/>Individual or fused ||Never ||Never ||Leuconoid
|-
! [[Demospongiae]]
|Single nucleus, single external membrane ||Silica ||In many species ||In some species<br />Made of [[aragonite]], if present<ref name="Hooper_2002"/><ref name="Bergquist_2001"/>||Leuconoid
|-
! [[Calcarea]]
|Single nucleus, single external membrane||[[Calcite]]<br/>individual or large masses ||Never ||Common<br/>Made of calcite, if present||Asconoid, syconoid, leuconoid or solenoid<ref name="Cavalcanti_2012">{{cite journal |last1=Cavalcanti |first1=F.F. |last2=Klautau |first2=M. |year=2011 |title=Solenoid: a new aquiferous system to Porifera |journal=Zoomorphology |volume=130 |issue=4 |pages=255–260 |doi=10.1007/s00435-011-0139-7 |s2cid=21745242 }}</ref>
|-
! [[Homoscleromorpha]]
|Single nucleus, single external membrane||Silica ||In many species ||Never ||Sylleibid or leuconoid
|}