Editing Sponge (section)

=== Fossil record ===
{{see also|Huainan biota}}

[[File:Raphidonema faringdonense 070715a.jpg|thumb|left|''[[Raphidonema (sponge)|Raphidonema faringdonense]]'', a fossil sponge from the [[Cretaceous]] of England]]
{{Annotated image |float=right|caption=[[Archaeocyathid]] structure|image=Archaeocyatha.png|width=150|image-width=150|height=235|image-top=-5|annotations=
{{Annotation|4|11|'''1'''}}
{{Annotation|9|60|'''2'''}}
{{Annotation|17|87|'''3'''}}
{{Annotation|27|124|'''4'''}}
{{Annotation|141|14|'''5'''}}
{{Annotation|139|64|'''6'''}}
{{Annotation|117|124|'''7'''}}
{{Annotation|2|175|'''1''':&nbsp;Gap&nbsp; '''2''':&nbsp;Central&nbsp;cavity&nbsp; '''3'''&nbsp;Internal wall&nbsp; '''4''':&nbsp;Pore (''all'' walls have pores)&nbsp; '''5'''&nbsp;Septum&nbsp; '''6'''&nbsp;Outer wall&nbsp; '''7'''&nbsp;Holdfast}}
}}

[[File:Nevadacoelia wistae.jpg|left|thumb|''[[Nevadacoelia|Nevadacoelia wistae]]'', a fossil [[Anthaspidellidae|anthaspidellid]] [[demosponge]] from the early [[Ordovician]] of [[Nevada]] ]]

Although [[molecular clock]]s and [[biomarker]]s suggest sponges existed well before the [[Cambrian explosion]] of life, [[silica]] spicules like those of demosponges are absent from the fossil record until the Cambrian.<ref>{{cite journal |last1=Sperling |first1=E. A. |last2=Robinson |first2=J. M. |last3=Pisani |first3=D. |last4=Peterson |first4=K. J. |date=January 2010 |title=Where's the glass? Biomarkers, molecular clocks, and microRNAs suggest a 200&nbsp;Myr missing Precambrian fossil record of siliceous sponge spicules |journal=Geobiology |volume=8 |issue=1 |pages=24–36 |pmid=19929965 |doi=10.1111/j.1472-4669.2009.00225.x |bibcode=2010Gbio....8...24S |s2cid=41195363 }}</ref> An unsubstantiated 2002 report exists of spicules in rocks dated around {{ma|750}}.<ref>{{cite book|last1= Reitner |first1=J |last2=Wörheide |first2=G. |contribution=Non-lithistid fossil Demospongiae – origins of their palaeobiodiversity and highlights in history of preservation |editor1=Hooper, J.N. |editor2=Van Soest, R.W. |year=2002 |title=Systema Porifera: A Guide to the Classification of Sponges |publisher=Kluwer Academic Plenum |location=New York, NY |url=http://webdoc.sub.gwdg.de/pub/geo/geobiologie/2005/reitner/2002-porifera.pdf |archive-url=https://web.archive.org/web/20081216220745/http://webdoc.sub.gwdg.de/pub/geo/geobiologie/2005/reitner/2002-porifera.pdf |archive-date=2008-12-16 |url-status=live |access-date=November 4, 2008}}</ref> Well-preserved [[fossil]] sponges from about {{ma|580}} in the [[Ediacaran]] period have been found in the [[Doushantuo Formation]].<ref>{{cite journal|last1=Li|first1=Chia-Wei|last2=Chen|first2=Jun-Yuan|last3=Hua|first3=Tzu-En|title=Precambrian sponges with cellular structures|journal=Science|date=February 1998|volume=279|issue=5352|pages=879–882|doi=10.1126/science.279.5352.879|pmid=9452391|bibcode=1998Sci...279..879L}}</ref> These fossils, which include: spicules; [[pinacocyte]]s; [[porocyte]]s; [[archeocyte]]s; [[sclerocyte]]s; and the internal cavity, have been classified as demosponges. The Ediacaran record of sponges also contains two other genera: the stem-hexactinellid ''[[Helicolocellus]]'' from the [[Dengying Formation]]<ref>{{cite journal |last1=Wang |first1=Xiaopeng |last2=Liu |first2=Alexander G. |last3=Chen |first3=Zhe |last4=Wu |first4=Chengxi |last5=Liu |first5=Yarong |last6=Wan |first6=Bin |last7=Pang |first7=Ke |last8=Zhou |first8=Chuanming |last9=Yuan |first9=Xunlai |last10=Xiao |first10=Shuhai |title=A late-Ediacaran crown-group sponge animal |journal=Nature |date=27 June 2024 |volume=630 |issue=8018 |pages=905–911 |doi=10.1038/s41586-024-07520-y|pmid=38839967 |bibcode=2024Natur.630..905W }}</ref> and the possible stem-archaeocyathan ''[[Arimasia]]'' from the [[Nama Group]].<ref name=arimasia>{{cite journal |last1=Runnegar |first1=Bruce |last2=Gehling |first2=James G. |last3=Jensen |first3=Sören |last4=Saltzman |first4=Matthew R. |title=Ediacaran paleobiology and biostratigraphy of the Nama Group, Namibia, with emphasis on the erniettomorphs, tubular and trace fossils, and a new sponge, Arimasia germsi n. gen. n. sp. |journal=Journal of Paleontology |date=October 2024 |volume=98 |issue=S94 |pages=1–59 |doi=10.1017/jpa.2023.81|bibcode=2024JPal...98S...1R }}</ref> These genera are both from the "Nama assemblage" of Ediacaran biota, although whether this is due to a genuine lack beforehand or preservational bias is uncertain. Fossils of [[glass sponge]]s have been found from around {{ma|540}} in rocks in Australia, China, and Mongolia.<ref name="Müller_2007">{{cite journal |last=Müller |first=W. E. G. |author2=Jinhe Li |last3=Schröder |first3=H. C. |author4=Li Qiao |author5=Xiaohong Wang |year=2007 |title=The unique skeleton of siliceous sponges (Porifera; Hexactinellida and Demospongiae) that evolved first from the Urmetazoa during the Proterozoic: a review |journal=Biogeosciences |volume=4 |issue=2 |pages=219–232 |bibcode=2007BGeo....4..219M |doi=10.5194/bg-4-219-2007 |doi-access=free }}</ref> Early Cambrian sponges from Mexico belonging to the genus ''Kiwetinokia'' show evidence of fusion of several smaller spicules to form a single large spicule.<ref>{{cite journal |last= McMenamin |first=M.A. |year=2008 |title=Early Cambrian sponge spicules from the Cerro Clemente and Cerro Rajón, Sonora, México |journal=[[Geologica Acta]] |volume=6 |issue=4 |pages=363–367 }}</ref> [[Calcium carbonate]] spicules of [[Calcarea|calcareous sponges]] have been found in Early Cambrian rocks from about {{ma|530|523}} in Australia. Other probable demosponges have been found in the Early [[Cambrian]] [[Chengjiang fauna]], from {{ma|525|520}}.<ref name="Li_1998">{{cite journal |last1=Li |first1=Chia-Wei |last2=Chen |first2=Jun-Yuan |last3=Hua |first3=Tzu-En |date=February 1998 |title=Precambrian sponges with cellular structures |journal=Science |volume=279 |issue=5352 |pages=879–82 |pmid=9452391 |doi=10.1126/science.279.5352.879 |bibcode=1998Sci...279..879L |s2cid=38837724 }}</ref> Fossils found in the Canadian Northwest Territories dating to {{ma|890}} may be sponges; if this finding is confirmed, it suggests the first animals appeared before the Neoproterozoic oxygenation event.<ref name="Turner_2021">{{cite journal |last=Turner |first=E.C. |title=Possible poriferan body fossils in early Neoproterozoic microbial reefs |journal=Nature |volume=596 |issue=7870 |pages=87–91 |date=August 2021 |pmid=34321662 |pmc=8338550 |doi=10.1038/s41586-021-03773-z |doi-access=free |bibcode=2021Natur.596...87T }}</ref>
[[File:Sauerstoffgehalt-1000mj2.png|thumb|left|Oxygen content of the atmosphere over the last billion years. If confirmed, the discovery of fossilized sponges dating to 890&nbsp;million years ago would predate the Neoproterozoic Oxygenation Event.]]

Freshwater sponges appear to be much younger, as the earliest known fossils date from the Mid-[[Eocene]] period about {{ma|48|40}}.<ref name="Müller_2007"/> Although about 90% of modern sponges are [[demosponges]], fossilized remains of this type are less common than those of other types because their skeletons are composed of relatively soft spongin that does not fossilize well.<ref name="Kazmierczak_2004">{{cite web |title=Demospongia |publisher=[[University of California, Berkeley|U.C. Berkeley]] |department=[[University of California Museum of Paleontology]] |place=Berkeley, CA |url=http://www.ucmp.berkeley.edu/porifera/demospongia.html |access-date=2008-11-27 |url-status=live |archive-url=https://web.archive.org/web/20131018230738/http://www.ucmp.berkeley.edu/porifera/demospongia.html |archive-date=October 18, 2013}}</ref>
The earliest sponge symbionts are known from the [[Llandovery epoch|early Silurian]].<ref name="Vinn_2015">{{cite journal |last1=Vinn |first1=Olev |last2=Wilson |first2=Mark A. |last3=Toom |first3=Ursula |last4=Mõtus |first4=Mari-Ann |year=2015 |title=Earliest known rugosan-stromatoporoid symbiosis from the Llandovery of Estonia (Baltica) |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=31 |pages=1–5 |bibcode=2015PPP...431....1V |doi=10.1016/j.palaeo.2015.04.023 |url=https://www.researchgate.net/publication/275657612 |access-date=2015-06-18 |archive-date=2024-04-10 |archive-url=https://web.archive.org/web/20240410181408/https://www.researchgate.net/publication/275657612_Earliest_known_rugosan-stromatoporoid_symbiosis_from_the_Llandovery_of_Estonia_Baltica |url-status=live }}</ref>

A chemical tracer is [[24-Isopropylcholestane|24-isopropyl cholestane]], which is a stable derivative of 24-isopropyl [[cholesterol]], which is said to be produced by [[demosponge]]s but not by [[eumetazoa]]ns ("true animals", i.e. [[cnidaria]]ns and [[bilateria]]ns). Since [[choanoflagellate]]s are thought to be animals' closest single-celled relatives, a team of scientists examined the [[biochemistry]] and [[gene]]s of one [[choanoflagellate]] species. They concluded that this species could not produce 24-isopropyl cholesterol but that investigation of a wider range of choanoflagellates would be necessary in order to prove that the fossil 24-isopropyl cholestane could only have been produced by demosponges.<ref>{{cite journal |last1=Kodner |first1=Robin B. |last2=Summons |first2=Roger E. |last3=Pearson |first3=Ann |last4=King |first4=Nicole |last5=Knoll |first5=Andrew H. |date=July 2008 |title=Sterols in a unicellular relative of the metazoans |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=105 |issue=29 |pages=9897–9902 |pmid=18632573 |pmc=2481317 |doi=10.1073/pnas.0803975105 |bibcode=2008PNAS..105.9897K |doi-access=free }}</ref>
Although a previous publication reported traces of the chemical 24-isopropyl cholestane in ancient rocks dating to {{ma|1800}},<ref>{{cite journal |last1=Nichols |first1=S. |last2=Wörheide |first2=G. |date=April 2005 |title=Sponges: New views of old animals |journal=Integrative and Comparative Biology |volume=45 |issue=2 |pages=333–334 |pmid=21676777 |doi=10.1093/icb/45.2.333 |citeseerx=10.1.1.598.4999 }}</ref> recent research using a much more accurately dated rock series has revealed that these biomarkers only appear before the end of the [[Marinoan glaciation]] approximately {{ma|635}},<ref>{{cite journal |last1=Love |first1=Gordon D. |last2=Grosjean |first2=Emmanuelle |last3=Stalvies |first3=Charlotte |last4=Fike |first4=David A. |last5=Grotzinger |first5=John P. |last6=Bradley |first6=Alexander S. |last7=Kelly |first7=Amy E. |last8=Bhatia |first8=Maya |last9=Meredith |first9=William |last10=Snape |first10=Colin E. |last11=Bowring |first11=Samuel A. |last12=Condon |first12=Daniel J. |last13=Summons |first13=Roger E. |display-authors=6 |date=February 2009 |title=Fossil steroids record the appearance of Demospongiae during the Cryogenian period |journal=Nature |volume=457 |issue=7230 |pages=718–721 |pmid=19194449 |doi=10.1038/nature07673 |bibcode=2009Natur.457..718L |s2cid=4314662 |url=https://authors.library.caltech.edu/14867/2/Love2009p34510.1038nature07673_supp.pdf |access-date=2019-08-01 |archive-url=https://web.archive.org/web/20180724144041/https://authors.library.caltech.edu/14867/2/Love2009p34510.1038nature07673_supp.pdf |archive-date=2018-07-24 |url-status=dead }}</ref> and that "Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, ~{{ma|713}} in Oman)". While it has been argued that this 'sponge biomarker' could have originated from marine algae, recent research suggests that the algae's ability to produce this biomarker evolved only in the [[Carboniferous]]; as such, the biomarker remains strongly supportive of the presence of demosponges in the Cryogenian.<ref name="Antcliffe_2013">{{cite journal |author=Antcliffe, J.B. |year=2013 |editor=Stouge, S. |title=Questioning the evidence of organic compounds called sponge biomarkers |journal=Palaeontology |volume=56 |issue=5 |pages=917–925 |doi=10.1111/pala.12030 |doi-access=free |bibcode=2013Palgy..56..917A }}</ref><ref>{{cite journal |author=Gold, D.A. |title=The slow rise of complex life as revealed through biomarker genetics |journal=Emerging Topics in Life Sciences |volume=2 |issue=2 |pages=191–199 |date=September 2018 |pmid=32412622 |doi=10.1042/ETLS20170150 |s2cid=90887224 }}</ref><ref>{{cite journal |last1=Gold |first1=David A. |last2=Grabenstatter |first2=Jonathan |last3=de Mendoza |first3=Alex |last4=Riesgo |first4=Ana |last5=Ruiz-Trillo |first5=Iñaki |last6=Summons |first6=Roger E. |date=March 2016 |title=Sterol and genomic analyses validate the sponge biomarker hypothesis |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=113 |issue=10 |pages=2684–2689 |pmid=26903629 |pmc=4790988 |doi=10.1073/pnas.1512614113 |bibcode=2016PNAS..113.2684G |doi-access=free }}</ref>

[[Archaeocyathid]]s, which some classify as a type of coralline sponge, are very common fossils in rocks from the Early [[Cambrian]] about {{ma|530|520}}, but apparently died out by the end of the Cambrian {{ma|490}}.<ref name="Li_1998"/>
It has been suggested that they were produced by: sponges; [[cnidaria]]ns; [[algae]]; [[foraminifera]]ns; a completely separate [[phylum]] of animals, Archaeocyatha; or even a completely separate [[Kingdom (biology)|kingdom]] of life, labeled Archaeata or Inferibionta. Since the 1990s, archaeocyathids have been regarded as a distinctive group of sponges.<ref name="Rowland_2001">{{cite journal |author1= Rowland, S.M. |author2=Stephens, T. |year=2001 |title=Archaeocyatha: A history of phylogenetic interpretation |journal=Journal of Paleontology |volume=75 |issue=6 |pages=1065–1078 |jstor=1307076 |doi=10.1666/0022-3360(2001)075<1065:AAHOPI>2.0.CO;2}}</ref>

{{clear left}}
{{Annotated image|float=left|caption=[[Halkieriid]] sclerite structure<ref name="Porter_2008"/> |image=Halkieriid sclerite structure 300.png |width=210 |height=96 |image-width=200 |image-left=0 |image-top=0
|annotations =
{{Annotation|141|44|{{=}} skin}}
{{Annotation|141|64|{{=}} [[aragonite]]}}
{{Annotation|141|84|{{=}} flesh}}
}}
It is difficult to fit [[chancelloriid]]s into classifications of sponges or more complex animals. An analysis in 1996 concluded that they were closely related to sponges on the grounds that the detailed structure of chancellorid sclerites ("armor plates") is similar to that of fibers of spongin, a [[collagen]] [[protein]], in modern keratose (horny) [[demosponge]]s such as ''[[Darwinella (sponge)|Darwinella]]''.<ref>{{cite journal |author1=Butterfield, N.J. |author2=Nicholas, C.J. |year=1996 |title=Burgess Shale-type preservation of both non-mineralizing and "shelly" Cambrian organisms from the Mackenzie Mountains, northwestern Canada |journal=Journal of Paleontology |volume=70 |issue=6 |pages=893–899 |jstor=1306492 |doi=10.1017/S0022336000038579 |bibcode=1996JPal...70..893B |s2cid=133427906 }}</ref> However, another analysis in 2002 concluded that chancelloriids are not sponges and may be intermediate between sponges and more complex animals, among other reasons because their skins were thicker and more tightly connected than those of sponges.<ref name="Janussen_2002">{{cite journal |last1=Janussen |first1=Dorte |last2=Steiner |first2=Michael |last3=Maoyan |first3=Zhu |year=2002 |title=New well-preserved scleritomes of Chancelloridae from the early Cambrian Yuanshan Formation (Chengjiang, China) and the middle Cambrian Wheeler Shale (Utah, USA) and paleobiological implications |journal=Journal of Paleontology |volume=76 |issue=4 |pages=596–606 |doi=10.1666/0022-3360(2002)076<0596:NWPSOC>2.0.CO;2|bibcode=2002JPal...76..596J |s2cid=129127213 }} free text at {{cite news |last=Janussen |first=D. |year=2002 |title=(full text without images) |journal=[[Journal of Paleontology]] |url=http://findarticles.com/p/articles/mi_qa3790/is_200207/ai_n9134583/pg_1?tag=artBody;col1 |access-date=2008-08-04 |archive-date=December 10, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081210092130/http://findarticles.com/p/articles/mi_qa3790/is_200207/ai_n9134583/pg_1?tag=artBody%3Bcol1}}</ref> In 2008, a detailed analysis of chancelloriids' sclerites concluded that they were very similar to those of [[halkieriid]]s, mobile [[bilaterian]] animals that looked like [[slug]]s in [[chain mail]] and whose fossils are found in rocks from the very Early Cambrian to the Mid Cambrian. If this is correct, it would create a dilemma, as it is extremely unlikely that totally unrelated organisms could have developed such similar sclerites independently, but the huge difference in the structures of their bodies makes it hard to see how they could be closely related.<ref name="Porter_2008">{{cite journal |last=Porter |first=S.M. |year=2008 |title=Skeletal microstructure indicates Chancelloriids and Halkieriids are closely related |journal=[[Palaeontology (journal)|Palaeontology]] |volume=51 |issue=4 |pages=865–879 |doi=10.1111/j.1475-4983.2008.00792.x |bibcode=2008Palgy..51..865P |doi-access=free}}</ref>