Spicules

Spicules are skeletal structures that occur in most sponges. They provide structural support, as well as deterrence against predators. Large spicules, visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. Spicules have four major symmetry types: Monaxon (simple cylinders with pointed ends), triaxon, tetraxon, and polyaxon. Sponges can be calcareous, siliceous, or composed of spongin. The meshing of numerous spicules serves as the sponge’s skeleton. The composition, size, and shape of spicules is one of the largest determining factors in sponge taxonomy. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... This article or section does not cite any references or sources. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus pore and ferre to bear) are animals of the phylum Porifera. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Diatoms are capable of synthesizing silica glass in vivo. ... A horny, sulfur-containing protein related to keratin that forms the skeletal structure of certain classes of sponges (American Heritage Dictionary, 2006) Proteinaceous comounds of which the spicules in Demospongiae are composed (Cartage, 2006) ... Look up taxonomy in Wiktionary, the free dictionary. ...

Spicules are formed by sclerocytes, which are derived from archaeocytes. The sclerocyte begins with an organic filament, and adds silica to it. Spicules are generally elongated at a rate of 1-10 μm per hour. Once the spicule reaches a certain length it protrudes from the sclerocyte cell body, but remains within the cell’s membrane. On occasion, sclerocytes may begin a second spicule while the first is still in progress. This does not cite any references or sources. ... Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmopshere with its magnetic field. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... // The cell membrane (also called the plasma membrane or plasmalemma) is a semipermeable lipid bilayer common to all living cells. ...

Recent research on the Euplectella aspergillum (Venus' Flower Basket) has demonstrated that the spicules of certain deep-sea sponges have similar traits to fiber optic cables. In addition to being able to trap and transport light, these spicules have a number of advantages over commercial fiber optic wire. The spicules are stronger, resist stress easier, and form their own support elements. Also, the low-temperature formation of the spicules, as compared to the high temperature stretching process of commercial fiber optics, allows for the addition of impurities which improve the refractive index. In addition, these spicules have built-in lenses in the ends which gather and focus light in dark conditions. It has been theorized that this ability may function as a light source for symbiotic algae (as with Rosella racovitzae) or as an attractor for shrimp which live inside the Venus' Flower Basket. However, a conclusive decision has not been reached; it may be that the light capabilities are simply a coincidental trait from a purely structural element. Binomial name Euplectella aspergillum Owen, 1841 The Venus Flower Basket, or Euplectella aspergillum, is the only Poriferan in the class Hexactenellida to be used in hobbyists aquariums. ... Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. ... Impurities are substances inside a confined amount of liquid, gas, or solid, which differ from the chemical composition of the material or compound. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... A lens. ... Meat Ants harvest Leaf Hoppers for their honey dew. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Superfamilies Alpheoidea Atyoidea Bresilioidea Campylonotoidea Crangonoidea Galatheacaridoidea Nematocarcinoidea Oplophoroidea Palaemonoidea Pandaloidea Pasiphaeoidea Procaridoidea Processoidea Psalidopodoidea Stylodactyloidea True shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. ...

It should be noted that the term spicule can also refer to structures on other organisms, such as the copulatory spicules of certain nematodes. A pair of lions copulating in the Maasai Mara, Kenya. ... Classes Adenophorea    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria The roundworms or nematodes (Phylum Nematoda from Gr. ...

References

• Aizenburg, Joanna., et al (2004). "Biological glass fibers: Correlation between optical and structural properties." Proceedings from the National Academy of Sciences of the USA. 101(10) 3358–3363.
• Imsiecke, George., et al (1995). "Formation of Spicules by Sclerocytes from the Freshwater Sponge Ephydatia Meulleri in Short-term Cultures in Vitro." In Vitro Cell. Dev. Biol-Animal. 31 528–535.

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