Spicule

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Sclerites (Greek σκληρός skleros "hard" ) are hard parts in the body of non- vertebrates, but the term does not refer to the bony skeleton parts or teeth of vertebrate animals or shells of molluscs. As spicules ( spicules ) they can serve the stability and as a protection against pests of flowers animals, sponges, echinoderms and tunicates or represent muscle attachment sites on the exoskeleton of arthropods or form the hard structures of teeth in the radula and tissues of molluscs. While many sclerites represent microscopic fine structures, which account for the largest up to three meters.

Determination

Sclerites have a characteristic shape and size and are therefore an important tool for taxonomic assignment (determination of species). The differentiation of the sclerites is also forensic importance is attached in the identification of species of blowflies in body parts.

The decay of marine invertebrates their Einzelsklerite are often released, they will become part of the oceanic detritus and part of the coral sand or the individual particles fill gaps in the substrate. The determination of fossil sclerites allowed taxonomic assignments and thus often the conclusion that sea depth and temperature, comparative analyzes can also provide conclusions on mode change, sea level fluctuations and temperature changes, and thus allow a climate chronology.

The fossil glass sponge Monorhaphis chuni formed, as some recent, only a single spicule be anchored, but the largest sclerite with up to three meters in length. Means of determining the oxygen isotopes and the distribution ratio of calcium to magnesium, the annual growth can be determined. While their thickness, annual rings ' allows statements about the then sea water temperature, the sequence of which is a climate archive and its counting the achieved age. When a Fund in the East China Sea as an age of 11,000 ± 3,000 years was determined.

Skleritom

For the entirety of the sclerites of an organ (eg radula ) or skeletal system of an invertebrate animal (eg, all spicules of the glass sponge ) coined Stefan Bengtson 1985 summarized the concept Skleritom. This term is less common, but is used.

Spicules

Spicules (Latin Spiculum " sting ", plural spicules ) are limestone ( calcite, CaCO3) or silica needles ( from silica, SiO2) in the body of many marine Non mollusc groups to stabilize their body shape, the needle shape is suitable to deter larger predators. In addition to the main mineral content they contain complex organic substances.

Coral

After the death of the soft corals not a massive skeletal remains as in the stony corals on hard parts remain only the sclerites. The leather coral Sinularia leptoclados the sclerites in the colony base, however, are so densely packed that up to six meters high reef structures arise from the residues. It is the only reef-building Corals.

The spicules of sponges ( sponge spicules ) are either spicules ( calcareous sponges ) or siliceous spicules ( siliceous sponges: glass sponges ).

Some glass sponges form a single spicule, but then a particularly large, the anchoring in the ground serving. Even in English, this is sometimes referred to as a stake nobility. An adaptation to special functions fulfill the hook-shaped sclerites of carnivorous horn silica sponge Chondrocladia turbiformis.

Skeletal remains of siliceous sponges can remain as so-called rattling stones after the death of the animals, with some sponge groups Einzelsklerite merge to form a rigid skeleton.

In the Horn siliceous sponges collagen- like Sponginfasern largely replace the spicules.

Molluscs

Some molluscs (especially nudibranchs ) that frequently bear in tissue embedded Kalkspicula to protect them from predators.

Echinoderms

For the echinoderms the storage of sclerites was eponymous.

Tunicates

Tunicates, sea squirts particular, show high variability of their Mikrospicula. While the oven Mania momus are two calcified Spiculatypen ago: 1.5-2.5 mm long, spindle-shaped, each with 100 or more rows of overlapping micro-tips and smaller spicules, each with 20-40 rows of non-overlapping micro-tips, which are anchored by a spider- like structure in the foot of the animal.

Arthropods

Sclerites form attachment points for the muscles to the exoskeleton of arthropods, such as the seeds of the fruit flies pump or the antenna joints of locusts.