Spinneret
Encyclopedia
A spinneret is a spider
's or insect
larva
's silk
-spinning organ
. It is usually on the underside of a spider's abdomen
, to the rear. While most spiders have six spinnerets, some have two, four, or eight. They move independently and in concert. Different species
of spiders use silk extruded from spinnerets to build webs
, to entrap insects by running round them, to make egg-cases, to catch the wind and fly (ballooning
), etc. Some insect larvae (including silkworms) extrude silk to make a protective cocoon for their metamorphosis
.
The discovery of silk-producing organs on the feet of the zebra tarantula (Aphonopelma seemanni
) has led to questions about the origins of spinnerets. It has been hypothesised that spinnerets were originally used as climbing aids on the feet and evolved and were used for webmaking at a later time.
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
's or insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
's silk
Spider silk
Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring...
-spinning organ
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
. It is usually on the underside of a spider's abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
, to the rear. While most spiders have six spinnerets, some have two, four, or eight. They move independently and in concert. Different species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of spiders use silk extruded from spinnerets to build webs
Spider web
A spider web, spiderweb, spider's web or cobweb is a device built by a spider out of proteinaceous spider silk extruded from its spinnerets....
, to entrap insects by running round them, to make egg-cases, to catch the wind and fly (ballooning
Ballooning (spider)
Ballooning is a term used for the mechanical kiting that many spiders, especially small species, as well as certain mites and some caterpillars use to disperse through the air. Many small spiders use gossamer or especially fine silk to lift themselves off a surface or use the silk as an anchor in...
), etc. Some insect larvae (including silkworms) extrude silk to make a protective cocoon for their metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
.
The discovery of silk-producing organs on the feet of the zebra tarantula (Aphonopelma seemanni
Aphonopelma seemanni
The Costa Rican Zebra Tarantula, also known as the Striped-knee Tarantula , inhabits most of western Costa Rica, as well as other parts of Central America, such as Guatemala, Honduras and Nicaragua. It is black with white stripes near the joint. Specimens from Nicaragua are tan-coloured.Zebra...
) has led to questions about the origins of spinnerets. It has been hypothesised that spinnerets were originally used as climbing aids on the feet and evolved and were used for webmaking at a later time.