Hexactinellid

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Glass sponges
Temporal range: Late Ediacaran–present [1]
Haeckel Hexactinellae.jpg
"Hexactinellae" from Ernst Haeckel's Kunstformen der Natur , 1904
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Porifera
Class: Hexactinellida
Schmidt, 1870
Subgroups

See text.

Synonyms
  • Hyalospongiae
Bolosoma stalked glass sponge Bolosoma stalked glass sponge (39506105791).jpg
Bolosoma stalked glass sponge

Hexactinellid sponges are sponges with a skeleton made of four- and/or six-pointed siliceous spicules, often referred to as glass sponges. They are usually classified along with other sponges in the phylum Porifera, but some researchers consider them sufficiently distinct to deserve their own phylum, Symplasma. Some experts believe glass sponges are the longest-lived animals on earth; [2] these scientists tentatively estimate a maximum age of up to 15,000 years.

Contents

Biology

Glass sponges are relatively uncommon and are mostly found at depths from 450 to 900 metres (1,480 to 2,950 ft) below sea level. Although the species Oopsacas minuta has been found in shallow water, others have been found much deeper. They are found in all oceans of the world, although they are particularly common in Antarctic and Northern Pacific waters. [3]

They are more-or-less cup-shaped animals, ranging from 10 to 30 centimetres (3.9 to 11.8 in) in height, with sturdy skeletons made of glass-like silica spicules, fused to form a lattice. [4] [5] In some glass sponges such as members of the genus Euplectela, these structures are aided by a protein called glassin. It helps accelerate the production of silicas from the silicic acid absorbed from the surrounding seawater. [6] The body is relatively symmetrical, with a large central cavity that, in many species, opens to the outside through a sieve formed from the skeleton. Some species of glass sponges are capable of fusing together to create reefs or bioherms. They are generally pale in colour, ranging from white to orange. [3]

Much of the body is composed of syncitial tissue, extensive regions of multinucleate cytoplasm. The epidermal cells characteristic of other sponges are absent, being replaced by a syncitial net of amoebocytes, through which the spicules penetrate. Unlike other sponges, they do not possess the ability to contract. [3]

Their body comprises three parts: the inner and outer peripheral trabecular networks, and the choanosome, which is used for feeding purposes. The choanosome acts as the mouth for the sponge while the inner and outer canals that meet at the choanosome are passages for the food, creating a consumption path for the sponge. [7]

All hexactinellids have the potential to grow to different sizes, but the average maximum growth is estimated to be around 32 centimeters long. Some grow past that length and continue to extend their length up to 1 meter long. The estimated life expectancy for hexactinellids that grow around 1 meter is approximately 200 years (Plyes).

The glass sponge Euplectella. .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{} Water flow Main syncitium Spicules Choanosyncitium and collar bodies showing interior Euplectella 01.png
The glass sponge Euplectella .
  Water flow
  Main syncitium
   Spicules
   Choanosyncitium and collar bodies showing interior

Glass sponges possess a unique system for rapidly conducting electrical impulses across their bodies, making it possible for them to respond quickly to external stimuli. [9] In the case Rhabdocalyptus dawsoni, the sponge uses electrical neuron signaling to detect outside stimuli, such as sediments, and then send a signal through its body system to alert the organism to no longer be actively feeding. Another glass sponge species in the same experiment of R. dawsoni, showed that the electrical conduction system for this class of sponges all has its own threshold of how much outside stimuli, sediments, etc., it can endure before it will stop its feeding process. [10] Species like "Venus' flower basket" have a tuft of fibers that extends outward like an inverted crown at the base of their skeleton. These fibers are 50 to 175 millimetres (2.0 to 6.9 in) long and about the thickness of a human hair.

Syncytia

Bodies of glass sponges are different from those other sponges in various other ways. For example, most of their cytoplasm is not divided into separate cells by membranes, but forms a syncytium or continuous mass of cytoplasm with many nuclei (e.g., Reiswig and Mackie, 1983); it is held suspended like a cobweb by a scaffolding-like framework made of silica spicules. [8] The remaining cells are connected to the syncytium by bridges of cytoplasmic "rivers" that transport nuclei, organelles ("organs" within cells) and other substances. [11] Instead of choanocytes, these bridges have further syncytia, known as choanosyncytia, which form bell-shaped chambers where water enters via perforations. The insides of these chambers are lined with "collar bodies", each consisting of a collar and flagellum but without a nucleus of its own. The motion of the flagella sucks water through passages in the "cobweb" and expels it via the open ends of the bell-shaped chambers. [8]

Some types of cells have a single nucleus and membrane each but are connected to other single-nucleus cells and to the main syncytium by "bridges" made of cytoplasm. The sclerocytes that build spicules have multiple nuclei, and in glass sponge larvae they are connected to other tissues by cytoplasm bridges; such connections between sclerocytes have not so far been found in adults, but this may simply reflect the difficulty of investigating such small-scale features. The bridges are controlled by "plugged junctions" that apparently permit some substances to pass while blocking others. [11]

This physiology is what allows for a greater flow of ions and electrical signals to move throughout the organism, with around 75% of the sponge tissue being fused in this way. [6] Another way is their role in the nutrient cycles of deep-sea environments. One species for example, Vazella pourtalesii, has an abundance of symbiotic microbes which aid in the nitrification and denitrification of the communities in which they are present. These interactions help the sponges survive in the low-oxygen conditions of the depths. [12]

Longevity

Venus' flower basket, Euplectella aspergillum Venus Flower Basket.jpg
Venus' flower basket, Euplectella aspergillum
Euplectella aspergillum Glass-sponge, Euplectella aspergillum.jpg
Euplectella aspergillum

These creatures are long-lived, but the exact age is hard to measure; one study based on modelling gave an estimated age of a specimen of Scolymastra joubini as 23,000 years (with a range from 13,000 to 40,000 years). However, due to changes in sea levels since the Last Glacial Maximum, its maximum age is thought to be no more than 15,000 years, [13] hence its listing of c. 15,000 years in the AnAge Database. [14] The shallow-water occurrence of hexactinellids is rare worldwide. In the Antarctic, two species occur as shallow as 33 meters under the ice. In the Mediterranean, one species occurs as shallow as 18 metres (59 ft) in a cave with deep water upwelling (Boury-Esnault & Vacelet (1994))

Reefs

The sponges form reefs (called sponge reefs) off the coast of British Columbia, southeast Alaska and Washington state, [15] which are studied in the Sponge Reef Project. In the case of Sarostegia oculata, this species almost always hosts symbiotic zoanthids, which cause the hexactinellid sponge to imitate the appearance and structure of coral reefs. [16] Only 33 species of this sponge have ever been reported in the South Atlantic until 2017 when the Shinkai 6500 submersible went on an expedition through the Rio Grande Rise. [16] Reefs discovered in Hecate Strait, British Columbia, have grown to up to 7 kilometres long and 20 metres high. Prior to these discoveries, sponge reefs were thought to have died out in the Jurassic period. [17] [18]

Reports of glass sponges have also been recorded on the HMCS Saskatchewan and HMCS Cape Breton wrecks off the coast of Vancouver Island. Species of zoantharin that rely on hexactinellid have also been found off the coast of the Japanese island of Minami-Torishima. Unidentified species of zoanthids have also been found in Australian waters, if these are identified as the same as the ones found in Minami-Torishima, this could potentially be proof of hexactinellids existing in all of the Pacific Ocean. [19]

Conservation

Most hexactinellids live in deep waters that are not impacted by human activities. However, there are glass sponge reefs off the coast of British Columbia. The Canadian government designated 2140 km2 of the Hecate strait and Queen Charlotte sound as a marine protected area. This area contains four glass sponge reefs. The new regulations prohibit bottom contact fishing within 200 meters of the sponge reefs. [20] Although human activities only affect a small portion of glass sponges, they are still subject to the threat of climate changes. Experiments using the species Aphrocallistes vastus have shown that increases in temperature and acidification can lead to weakened skeletal strength and stiffness. [21] In 1995, an Antarctic ice shelf collapsed due to climate change. Since then, studies of the area have shown that hexactinellid reefs have been increasing in size despite the changes in climate. [22]

Classification

The earliest known hexactinellids are from the earliest Cambrian or late Neoproterozoic eras. They are fairly common relative to demosponges as fossils, but this is thought to be, at least in part, because their spicules are sturdier than spongin and fossilize better. Like almost all sponges, the hexactinellids draw water in through a series of small pores by the whip-like beating of a series of hairs or flagella in chambers which in this group line the sponge wall.

The class is divided into two subclasses and several orders: [23]

Class Hexactinellida

See also

Related Research Articles

<span class="mw-page-title-main">Sponge</span> Animals of the phylum Porifera

Sponges or sea sponges are members of the metazoan phylum Porifera, a basal animal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important reef-building organisms.

<span class="mw-page-title-main">Venus' flower basket</span> Species of sponge

The Venus' flower basket is a glass sponge in the phylum Porifera. It is a marine sponge found in the deep waters of the Pacific Ocean, usually at depths below 500 m (1,600 ft). Like other sponges, they feed by filtering sea water to capture plankton and marine snow. Similar to other glass sponges, they build their skeletons out of silica, which forms a unique lattice structure of spicules. The sponges are usually between 10 cm (3.9 in) and 30 cm (12 in) tall, and their bodies act as refuge for their mutualist shrimp partners. This body structure is of great interest in materials science as the optical and mechanical properties are in some ways superior to man-made materials. Little is known regarding their reproduction habits, however fluid dynamics of their body structure likely influence reproduction and it is hypothesized that they may be hermaphroditic.

<span class="mw-page-title-main">Demosponge</span> Class of sponges

Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include greater than 90% of all species of sponges with nearly 8,800 species worldwide. They are sponges with a soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite. They are predominantly leuconoid in structure. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica, or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges. Some species, in particular from the Antarctic, obtain the silica for spicule building from the ingestion of siliceous diatoms.

<span class="mw-page-title-main">Siliceous sponge</span> Clade of sponges

The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges.

<span class="mw-page-title-main">Hexasterophora</span> Subclass of Hexactinellid sponges

Hexasterophora are a subclass of glass sponges in the class Hexactinellida. Most living hexasterophorans can be divided into three orders: Lyssacinosida, Lychniscosida, and Sceptrulophora. Like other glass sponges, hexasterophorans have skeletons composed of overlapping six-rayed spicules. In addition, they can be characterized by the presence of hexasters, a type of microsclere with six rays unfurling into multi-branched structures.

<span class="mw-page-title-main">Sponge reef</span> Reefs produced by sea sponges.

Sponge reefs are reefs produced by sea sponges. All modern sponge reefs are formed by hexactinellid sponges, which have an endoskeleton made of silica spicules and are often referred to as "glass sponges", while historically the non-spiculed, calcite-skeletoned archaeocyathid and stromatoporoid sponges were the primary reef-builders.

<span class="mw-page-title-main">Cloud sponge</span> Species of sponge

The cloud sponge(Aphrocallistes vastus) is a species of sea sponge in the class Hexactinellida. It is a deep-water reef-forming animal. The species was first described by F.E. Schulze in 1886.

<span class="mw-page-title-main">Sponge spicule</span> Structural element of sea sponges

Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators.

<i>Suberites</i> Genus of sponges

Suberites is a genus of sea sponges in the family Suberitidae. Sponges, known scientifically as Porifera, are the oldest metazoans and are used to elucidate the basics of multicellular evolution. These living fossils are ideal for studying the principal features of metazoans, such as extracellular matrix interactions, signal-receptor systems, nervous or sensory systems, and primitive immune systems. Thus, sponges are useful tools with which to study early animal evolution. They appeared approximately 580 million years ago, in the Ediacaran.

Monorhaphis is a monotypic genus of siliceous deep sea Hexactinellid sponges. The single species is the type species Monorhaphis chuni, a sponge known for creating a single giant basal spicule (G.B.S.) to anchor the sponge in the sediments. The species was described by Franz Eilhard Schulze in 1904 from specimens collected by the German Deep Sea Expedition in 1898–1899. Monorhaphis is also the only genus in the monotypic family Monorhaphididae.

<i>Euplectella</i> Genus of sponges

Euplectella is a genus of glass sponges which includes the well-known Venus' Flower Basket. Glass sponges have a skeleton made up of silica spicules that can form geometric patterns. These animals are most commonly found on muddy sea bottoms in the Western Pacific and Indian Oceans. They are sessile organisms and do not move once attached to a rock. They can be found at depths between 100 m and 1000 m but are most commonly found at depths greater than 500 m.

<span class="mw-page-title-main">Reticulosa</span> Extinct order of sponges

Reticulosa is an extinct order of sea sponges in the class Hexactinellida and the subclass Amphidiscophora. Reticulosans were diverse in shape and size, similar to their modern relatives, the amphidiscosidans. Some were smooth and attached to a surface at a flat point, others were polyhedral or ornamented with nodes, many were covered in bristles, and a few were even suspended above the seabed by a rope-like anchor of braided glass spicules.

<span class="mw-page-title-main">Amphidiscosida</span> Order of sponges

Amphidiscosida is an order of hexactinellids. The Amphidiscosida are commonly regarded as the only living sponges in the subclass Amphidiscophora.

<span class="mw-page-title-main">Silicatein</span>

Silicateins are enzymes which catalyse the formation of biosilica from monomeric silicon compounds extracted from the natural environment. Environmental silicates are absorbed by specific biota, including diatoms, radiolaria, silicoflagellates, and siliceous sponges; silicateins have so far only been found in sponges. Silicateins are homologous to the cysteine protease cathepsin.

Claviscopulia is a genus of glass sponge in the family Farreidae.

<i>Bolosoma</i> Genus of sponges

Bolosoma is a genus of pedunculated siliceous sponges belonging to the family Euplectellidae. This genus lives in deep-sea environments and provides a habitat for a plethora of other benthic species, giving Bolosoma an incredibly important ecological role in the ecosystems it is a part of.

Lychniscosida is an order of sponges belonging to the class Hexactinellida and subclass Hexasterophora. They are dictyonal sponges characterized by the presence of additional struts at the nodes of the skeleton. These struts create octahedral frames, known as lychniscs ("lanterns").

<i>Rossella</i> (sponge) Genus of glass sponges

Rosella is a genus of glass sponges in the family Rossellidae. It is found in the Antarctic and sub-Antarctic regions.

Rossella antarctica is a relatively small species of glass sponge. It is widely distributed in the southern hemisphere, particularly in the Antarctic and sub-Antarctic regions.

Oopsacas minuta is a species of glass sponge found in cold submarine caves in the Mediterranean. Unlike most glass sponges, O. minuta lives in shallow waters above 200 meters in depth. At this depth the temperature is low and constant, so silica metabolism is optimized.

References

  1. ↑ Brasier, Martin; Green, Owen; Shields, Graham (April 1997). "Ediacarian sponge spicule clusters from southwestern Mongolia and the origins of the Cambrian fauna" (PDF). Geology. 25 (4): 303–306. Bibcode:1997Geo....25..303B. doi:10.1130/0091-7613(1997)025<0303:ESSCFS>2.3.CO;2.
  2. ↑ "Hexactinellid sponge (Scolymastra joubini) longevity, ageing, and life history". genomics.senescence.info. Retrieved 2 March 2023.
  3. 1 2 3 Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia: Holt-Saunders International. p. 104. ISBN   978-0-03-056747-6.
  4. ↑ "Glass Sponges, the Living Ornaments of the Deep Sea". Schmidt Ocean Institute. 2020-10-01. Retrieved 2023-06-11.
  5. ↑ US Department of Commerce, National Oceanic and Atmospheric Administration. "What is a glass sponge?". oceanservice.noaa.gov. Retrieved 2023-06-11.
  6. 1 2 Nishi, Michika; Kobayashi, Hiroki; Amano, Taro; Sakate, Yuto; Bito, Tomohiro; Arima, Jiro; Shimizu, Katsuhiko (2020-12-01). "Identification of the Domains Involved in Promotion of Silica Formation in Glassin, a Protein Occluded in Hexactinellid Sponge Biosilica, for Development of a Tag for Purification and Immobilization of Recombinant Proteins". Marine Biotechnology. 22 (6): 739–747. Bibcode:2020MarBt..22..739N. doi:10.1007/s10126-020-09967-2. ISSN   1436-2236. PMID   32291549. S2CID   215761084.
  7. ↑ "Gale - Institution Finder".
  8. 1 2 3 Ruppert RE, Fox RS, Barnes RD (2004). Invertebrate Zoology (7th ed.). Brooks / COLE Publishing. pp. 76–97. ISBN   978-0-03-025982-1.
  9. ↑ Lawrence, Eleanor (1999). "Nervous sponge". Nature. doi:10.1038/news990415-5.
  10. ↑ Tompkins-MacDonald, Gabrielle J.; Leys, Sally P. (2008-05-15). "Glass sponges arrest pumping in response to sediment: implications for the physiology of the hexactinellid conduction system". Marine Biology. 154 (6): 973–984. Bibcode:2008MarBi.154..973T. doi:10.1007/s00227-008-0987-y. ISSN   0025-3162. S2CID   54079172.
  11. 1 2 Leys SP (February 2003). "The significance of syncytial tissues for the position of the hexactinellida in the metazoa". Integrative and Comparative Biology. 43 (1): 19–27. doi: 10.1093/icb/43.1.19 . PMID   21680406.
  12. ↑ Maldonado, Manuel; López-Acosta, María; Busch, Kathrin; Slaby, Beate M.; Bayer, Kristina; Beazley, Lindsay; Hentschel, Ute; Kenchington, Ellen; Rapp, Hans Tore (2021). "A Microbial Nitrogen Engine Modulated by Bacteriosyncytia in Hexactinellid Sponges: Ecological Implications for Deep-Sea Communities". Frontiers in Marine Science. 8. doi: 10.3389/fmars.2021.638505 . hdl: 10261/235467 . ISSN   2296-7745.
  13. ↑ Susanne Gatti (2002). "The Role of Sponges in High-Antarctic Carbon and Silicon Cycling - a Modelling Approach" (PDF). Ber. Polarforsch. Meeresforsch. 434. ISSN   1618-3193. Archived from the original (PDF) on 2011-07-24. Retrieved 2009-05-25.
  14. ↑ "Hexactinellid information from the AnAge Database".
  15. ↑ Stiffler, Lisa (2007-07-27). "Reef of glass sponges found off Washington's coast". Seattle Post-Intelligencer.
  16. 1 2 Hajdu, Eduardo; Castello-Branco, Cristiana; Lopes, Daniela A.; Sumida, Paulo Yukio Gomes; Perez, Jose Angel Alvarez (December 2017). "Deep-sea dives reveal an unexpected hexactinellid sponge garden on the Rio Grande Rise (SW Atlantic). A mimicking habitat?". Deep Sea Research Part II: Topical Studies in Oceanography. 146: 93–100. Bibcode:2017DSRII.146...93H. doi:10.1016/j.dsr2.2017.11.009.
  17. ↑ "B.C.'s Reefs Among Science's Great Finds". Georgia Straight Vancouver's News & Entertainment Weekly. 2005-02-24. Retrieved 2017-05-22.
  18. ↑ "Diving deep for glass sponges". CBC Radio . Retrieved 2017-05-22.
  19. ↑ Kise, Hiroki; Nishijima, Miyuki; Iguchi, Akira; Minatoya, Junpei; Yokooka, Hiroyuki; Ise, Yuji; Suzuki, Atsushi (2023-03-24). "A new hexactinellid-sponge-associated zoantharian (Porifera, Hexasterophora) from the northwestern Pacific Ocean". ZooKeys (1156): 71–85. Bibcode:2023ZooK.1156...71K. doi: 10.3897/zookeys.1156.96698 . ISSN   1313-2970. PMC   10208231 . PMID   37234793.
  20. ↑ Government of Canada, Fisheries and Oceans Canada (2019-09-18). "Hecate Strait/Queen Charlotte Sound Glass Sponge Reefs Marine Protected Area (HS/QCS MPA)". www.dfo-mpo.gc.ca. Retrieved 2023-10-06.
  21. ↑ Stevenson, A.; Archer, S. K.; Schultz, J. A.; Dunham, A.; Marliave, J. B.; Martone, P.; Harley, C. D. G. (2020-05-18). "Warming and acidification threaten glass sponge Aphrocallistes vastus pumping and reef formation". Scientific Reports. 10 (1): 8176. Bibcode:2020NatSR..10.8176S. doi:10.1038/s41598-020-65220-9. ISSN   2045-2322. PMC   7235243 . PMID   32424237.
  22. ↑ Fillinger, Laura; Janussen, Dorte; Lundalv, Tomas; Richter, Claudio (July 22, 2013). "Rapid glass sponge expansion after climate-induce Antarctic ice shelf collapse". Current Biology. 23 (14): 1330–1334. Bibcode:2013CBio...23.1330F. doi: 10.1016/j.cub.2013.05.051 . PMID   23850279. S2CID   18142746.
  23. ↑ "Hexactinellida". WoRMS. World Register of Marine Species.
  24. 1 2 Treatise on Invertebrate Paleontology Part E, Revised. Porifera, Volume 3: Classes Demospongea, Hexactinellida, Heteractinida & Calcarea, xxxi + 872 p., 506 fig., 1 table, 2004, available here. ISBN   0-8137-3131-3.
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