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Related to Spicule: spongin


see chromospherechromosphere
[Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (the sun's visible surface) and the corona (its outer atmosphere).
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Spicules are spike-like prominences visible at the limb of the sun during solar eclipses or during observation of the sun in monochromatic light, for example, the light of the hydrogen line Hλ. They extend into the solar corona to heights of 6,000–10,000 km and have diameters of 200–2,000 km. The average lifetime of a spicule is 5–7 min. Spicules move upward at speeds of 20–30 km/sec; the speeds of internal movements are 5–10 km/sec. The temperature of a spicule is approximately 8000°K in the lower part and about 16,000°K in the upper part. The density of spicules varies with height from 2 × 1011 to 3 × 1010 atoms/cm3. Hundreds of thousands of spicules exist on the sun at one time. They arise primarily at the edges of the cells of the chromospheric network.



(1) In certain invertebrates a skeletal element consisting of calcium carbonate or, less commonly, silica (silicon dioxide). Spicules occur in sponges (in the form of one-, three-, four-, and many-rayed needles), octocorallians, aplacophorans, mollusks, holothurians and other echinoderms (in the form of small wheels, anchors, or lattices), and ascidians (in the form of thorny spheres).

(2) In nematodes, a part of the male copulatory organ. In some species the spicules are supplementary formations; they protrude from the cloacal opening of the male and serve to widen the female’s vagina. In other species sulcate spicules come together and conduct the spermatozoa into the vagina of the female.


One of an irregular distribution of jets shooting up from the sun's chromosphere. Also known as solar spicule.
An empty diatom shell.
(invertebrate zoology)
A calcareous or siliceous, usually spikelike supporting structure in many invertebrates, particularly in sponges and alcyonarians.
References in periodicals archive ?
AQPs also have been identified in sponges, and are associated with dehydration and biosilica hardening in species that synthesize spicules (Muller et al.
Raman analysis of the crystals, present as the 'head' of the spicules as well as isolated clusters, using a 532 nm laser, confirmed they were quartz.
Precloca or species Spicule length(p) midventral fans affinis 220-230 6 cahirensis 170 7 splindida 207 8 author's 275 8 specimen
The presence of tridents, spicules and longitudinal ridges are the main characteristics of the genus Camallannus were suggested by Moravec (1973) and Gupta and Verma (1978).
At first glance, spicules are thought to have a magnetic origin, as these fields seem to flood the chromosphere [148, 150, 206-215].
Moreover, it has been demonstrated that the influence of silica concentration on spicule growth may influence not only spicule shape and size, but also the phenotypic expression of several spicule types which are available genetically for a certain sponge (Maldonado et al.
Scientists led by Wolfgang Tremel, a professor at Johannes Gutenberg Universitat Mainz, built the artificial spicules by mixing silicatein-[alpha] with calcite.
in males, presence of the spicular tube, and lengths of the spicule, cloacal tube and esophagus).
They can appear as a variety of shapes often described by observers as mounds, trees or hedgerows, and can form arches, loops, spires or spicules.
Deep-water sediments contain ice-rafted coarsegrained components and biogenic elements such as sponge spicules that are heavily used by numerous agglutinated species for test construction.