User:MadisonOliver7/Hexactinellid

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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. 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. 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.'''

Biology

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. 'In the case Rhabdocalyptus dawsoni,'' the sponge uses electrical signaling to detect outside stimuli, such as sediments, that cause it to halt its feeding process as a response. Another species in the same experiment of R. dawsoni, showed that the electrical conduction system for this class of sponges all has its own limit of when they will detect outside stimuli that would cause a feeding halt response.''' 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.

Reefs

The sponges form reefs (called sponge reefs) off the coast of British Columbia, southeast Alaska and Washington state, which are studied in the Sponge Reef Project. In the case of Sarostegia oculata, this species almost always hosts symbiotic zoanthrids, which cause the hexactinellid sponge to imitate the appearance and structure of coral reefs. Only 33 species of this sponge have ever been reported in the South Atlantic until recently with the Shinkai 6500 submersible expedition through the Rio Grande Rise. 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. '''Fossil cliffs can be found across parts of Spain, France, Germany, and Romania. These cliffs are the remnants of glass sponge reefs that were alive over 40 million years ago'''.

Reports of glass sponges have also been recorded on the HCMS Saskatchewan and HCMS 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 zoantharin have also been found in Australian waters, if these are identified as the same as the ones found in Miami-Torishima, the existence of hexactinellid in the entire Pacific Ocean could be inferred.''' Hasari -

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. '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.''' The body is relatively symmetrical, with a large central cavity that, in many specie, 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.

Glass sponges are different from other sponges in various other ways. For example, most of the 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). '''The remaining cells are connected to the syncytium by cytoplasmic bridges. 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. 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.'''