Spinneret

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The spinnerets of an Australian garden orb weaver spider. Australian garden orb weaver spider spinneret.jpg
The spinnerets of an Australian garden orb weaver spider.
Black spinneret of Phidippus adumbratus visible below red abdomen Spinneret of Phidippus adumbratus.jpg
Black spinneret of Phidippus adumbratus visible below red abdomen

A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. [1] Spinnerets are usually on the underside of a spider's opisthosoma, and are typically segmented. [2] [3] While most spiders have six spinnerets, some have two, four, or eight. [4] They can move both independently and in concert.

Contents

Most spinnerets are not simple structures with a single orifice producing a single thread, but complex structures of many microscopic spigots, each producing one filament. This produces the necessary orientation of the protein molecules, without which the silk would be weak and useless. Spigots can be singular or found in groups, which also permits spiders to combine multiple filaments in different ways to produce many kinds of silk for various purposes. Spinneret morphology can help arachnologists identify the taxon of a specimen and the specific morphology of a spigot can determine its use as well. For example, flagelliform spigot is unique to Araneoidea, and another kind of spigot found in sets of three, referred to as cylindrical gland spots, are found only in females and used for making egg sacs. [5] The desert grass spider, Agelenopsis aperta, has especially prominent spinnerets that extend out of the end of their abdomen. [6]

Various species of spiders use silk extruded from spinnerets to build webs, to transfer sperm, to entrap insects by wrapping it around them, to make egg-cases, to manipulate static electricity in the air, and to fly (ballooning), etc.

Some insect larvae (including silkworms) extrude silk to make a protective cocoon for their metamorphosis. The insects known as web spinners weave silken galleries for protection from predators and the elements while foraging and breeding. [7]

Evolution

Observations suggesting that there might be silk-producing organs on the feet of the zebra tarantula ( Aphonopelma seemanni ) led to questions about the origins of spinnerets. It was hypothesised that spinnerets in spiders were originally used as climbing aids on the feet and evolved and were used for webmaking at a later time. [8]

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<span class="mw-page-title-main">Spider silk</span> Protein fiber made by spiders

Spider silk is a protein fibre or silk spun by spiders. Spiders use silk to make webs or other structures that function as adhesive traps to catch prey, to entangle and restrain prey before biting, to transmit tactile information, or as nests or cocoons to protect their offspring. They can use the silk to suspend themselves from height, to float through the air, or to glide away from predators. Most spiders vary the thickness and adhesiveness of their silk according to its use.

<span class="mw-page-title-main">Arachnid</span> Class of arthropods

Arachnids are arthropods in the class Arachnida of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroons.

<span class="mw-page-title-main">Embioptera</span> Order of insects

The order Embioptera, commonly known as webspinners or footspinners, are a small group of mostly tropical and subtropical insects, classified under the subclass Pterygota. The order has also been called Embiodea or Embiidina. More than 400 species in 11 families have been described, the oldest known fossils of the group being from the mid-Jurassic. Species are very similar in appearance, having long, flexible bodies, short legs, and only males having wings.

<i>Lycosa tarantula</i> Species of arachnid

Lycosa tarantula is the species originally known as the tarantula, a name that nowadays in English commonly refers to spiders in another family entirely, the Theraphosidae. It now may be better called the tarantula wolf spider, being in the wolf spider family, the Lycosidae. L. tarantula is a large species found in southern Europe, especially in the Apulia region of Italy and near the city of Taranto, from which it gets its name.

<span class="mw-page-title-main">Tetrapulmonata</span> Clade of arachnids

Tetrapulmonata is a non-ranked supra-ordinal clade of arachnids. It is composed of the extant orders Uropygi, Schizomida, Amblypygi and Araneae (spiders). It is the only supra-ordinal group of arachnids that is strongly supported in molecular phylogenetic studies. Two extinct orders are also placed in this clade, Haptopoda and Uraraneida. In 2016, a newly described fossil arachnid, Idmonarachne, was also included in the Tetrapulmonata; as of March 2016 it has not been assigned to an order.

<i>Argiope aurantia</i> Species of spider

Argiope aurantia is a species of spider, commonly known as the yellow garden spider, black and yellow garden spider, golden garden spider, writing spider, zigzag spider, zipper spider, black and yellow argiope, corn spider, Steeler spider, or McKinley spider. The species was first described by Hippolyte Lucas in 1833. It is common to the contiguous United States, Hawaii, southern Canada, Mexico, and Central America. It has distinctive yellow and black markings on the abdomen and a mostly white cephalothorax. Its scientific Latin name translates to "gilded silver-face". The body length of males range from 5–9 mm (0.20–0.35 in); females range from 19–28 mm (0.75–1.10 in). These spiders may bite if disturbed or harassed, but the venom is harmless to non-allergic humans, roughly equivalent to a bumblebee sting in intensity.

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

Cribellum literally means "little sieve", and in biology the term generally applies to anatomical structures in the form of tiny perforated plates.

<span class="mw-page-title-main">Evolution of spiders</span> Origin from a chelicerate ancestor and diversification of spiders through geologic time

The evolution of spiders has been ongoing for at least 380 million years. The group's origins lie within an arachnid sub-group defined by the presence of book lungs ; the arachnids as a whole evolved from aquatic chelicerate ancestors. More than 45,000 extant species have been described, organised taxonomically in 3,958 genera and 114 families. There may be more than 120,000 species. Fossil diversity rates make up a larger proportion than extant diversity would suggest with 1,593 arachnid species described out of 1,952 recognized chelicerates. Both extant and fossil species are described annually by researchers in the field. Major developments in spider evolution include the development of spinnerets and silk secretion.

<span class="mw-page-title-main">Spider anatomy</span> Physiology of Spiders (order Araneae)

The anatomy of spiders includes many characteristics shared with other arachnids. These characteristics include bodies divided into two tagmata, eight jointed legs, no wings or antennae, the presence of chelicerae and pedipalps, simple eyes, and an exoskeleton, which is periodically shed.

<i>Uloborus plumipes</i> Species of spider

Uloborus plumipes is a species of Old World cribellate spider in the family Uloboridae. Common names include the feather-legged lace weaver and the garden centre spider, the latter name being due to its frequent occurrence of this spider in garden centres. The species name is derived from the Latin pluma "feather" and pes "foot".

<span class="mw-page-title-main">Tarantula</span> Family of spiders

Tarantulas comprise a group of large and often hairy spiders of the family Theraphosidae. As of December 2023, 1,100 species have been identified, with 166 genera. The term "tarantula" is usually used to describe members of the family Theraphosidae, although many other members of the same infraorder (Mygalomorphae) are commonly referred to as "tarantulas" or "false tarantulas". Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have setae known as urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.

<i>Attercopus</i> Extinct genus of spider-like arachnids

Attercopus is an extinct genus of arachnids, containing one species Attercopus fimbriunguis, known from flattened cuticle fossils from the Panther Mountain Formation in Upstate New York. It is placed in the extinct order Uraraneida, spider-like animals able to produce silk, but which lacked true spinnerets and retained a segmented abdomen bearing a flagellum-like tail resembling that of a whip scorpion. They are thought to be close to the origins of spiders.

<i>Cyrtophora citricola</i> Species of spider

Cyrtophora citricola, also known as the tropical tent-web spider, is an orb-weaver spider in the family Araneidae. It is found in Asia, Africa, Australia, Costa Rica, Hispaniola, Colombia, and Southern Europe and in 2000, it was discovered in Florida. C. citricola differs from many of its close relatives due its ability to live in a wide variety of environments. In North America and South America, the spider has caused extensive damage to agricultural operations.

<span class="mw-page-title-main">Spider</span> Order of arachnids

Spiders are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except Antarctica, and have become established in nearly every land habitat. As of November 2023, 51,673 spider species in 136 families have been recorded by taxonomists. However, there has been debate among scientists about how families should be classified, with over 20 different classifications proposed since 1900.

<i>Psalmopoeus irminia</i> Species of spider

Psalmopoeus irminia, also known as the Venezuelan suntiger, is a species of tarantula endemic to Venezuela, Guyana and Brazil. They were first described in 1994 by F. Saager.

This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids.

Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testicle or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the sperm and are then expelled from the body ("laid"), in most cases via an ovipositor.

<span class="mw-page-title-main">Uraraneida</span> Order of arachnids

Uraraneida is an extinct order of Paleozoic arachnids related to modern spiders. Two genera of fossils have been definitively placed in this order: Attercopus from the Devonian of United States and Permarachne from the Permian of Russia. Like spiders, they are known to have produced silk, but lack the characteristic spinnerets of modern spiders, and retain elongate telsons.

Agelenopsis pennsylvanica, commonly known as the Pennsylvania funnel-web spider or the Pennsylvania grass spider, is a species of spider in the family Agelenidae. The common name comes from the place that it was described, Pennsylvania, and the funnel shape of its web. Its closest relative is Agelenopsis potteri.

<i>Pardosa milvina</i> Species of arachnid

Pardosa milvina, the shore spider, is a species in the wolf spider family. They are mainly found near rivers and in agricultural areas in eastern North America. P. milvina feed on a large variety of small insects and spiders. Ground beetles such as Scarites quadriceps and large wolf spiders such as Tigrosa helluo are predators of P. milvina. P. milvina are smaller spiders with thin, long legs. This species captures prey such as arthropods with their legs and then kills them with their venom. Their predators are larger wolf spiders and beetles. P. milvina are able to detect these predators from chemotactile and vibratory cues. These spiders lose limbs when escaping from predators and they can change their preferred location in order to avoid predators. P. milvina also use chemical cues in order to mate. During their mating ritual, the male raises his legs and shakes his body. Both males and females can use silk, a chemotactile cue, for sexual communication. Additionally, female shore spiders heavily invest in their offspring, keeping them in egg sacs and carrying them for a few weeks after they are born.

References

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  2. Wiggins, Charlotte (Nov 10, 2013). "Gardening to Distraction: Along came a spider". The Rolla Daily News. Therolladailynews.com. Retrieved December 1, 2013.
  3. Pechmann, Matthias; Khadjeh, Sara; Sprenger, Frederik; Prpic, Nikola-Michael (2010). "Patterning mechanisms and morphological diversity of spider appendages and their importance for spider evolution". Arthropod Structure and Development. 39 (6): 453–467. doi:10.1016/j.asd.2010.07.007. PMID   20696272.
  4. Spider Identification – Types of Spiders, Retrieved December 1, 2013
  5. Coddington, Jonathan A. (Spring 1989). "Spinneret Silk Spigot Morphology: Evidence for the Monophyly of Orbweaving Spiders, Cyrtophorinae (Araneidae), and the Group Theridiidae Plus Nesticidae". The Journal of Arachnology. 17 (1). American Arachological Society: 71–95. JSTOR   3705406 . Retrieved 31 August 2020.
  6. Bradley, Richard A. (2012-12-18), "FAMILY CLUBIONIDAE • Sac Spiders", Common Spiders of North America, University of California Press, pp. 105–106, doi:10.1525/california/9780520274884.003.0014, ISBN   978-0-520-27488-4 , retrieved 2020-12-08
  7. Richards, O. W.; Davies, R.G. (1977). Imms' General Textbook of Entomology: Volume 1: Structure, Physiology and Development Volume 2: Classification and Biology. Berlin: Springer. ISBN   0-412-61390-5.
  8. Gorb, SN; Niederegger S; Hayashi CY; Summers AP; Votsch W; Walther P (September 28, 2006). "Bio materials: silk-like secretion from tarantula feet". Nature. 443 (7110): 407. Bibcode:2006Natur.443..407G. doi: 10.1038/443407a . PMID   17006505. S2CID   4415648.