Tetragnatha extensa
Encyclopedia
Tetragnatha extensa is a species
of spider
found across the Northern Hemisphere
. It has an elongate body, up to 11 mm (0.433070866141732 in) long, and adopts a straight line posture when alarmed. It lives on low vegetation in damp areas, and feeds on flying insects which it catches in its web.
. In North America
, it is found from Alaska
to Newfoundland, and its range extends south to Washington, Colorado
and Pennsylvania
. The species has a broad ecological range, having been found at the tree line in the Rocky Mountains
and in coastal vegetation in Europe
. T. extensa is found throughout the United Kingdom
, where it is the commonest species of Tetragnatha
, and one of the commonest spiders. The colouring of T. extensa is quite variable, ranging from creamy-yellow to green. On the underside, there is a thick black central band, with a silvery band on either side.
T. extensa is distinguished from other members of the genus Tetragnatha
by the minute curved tip of the male's conductor (part of the pedipalp
), and the form of the female's spermatheca
.
s, including mosquito
s, midge
s and moth
s, which it catches in its loosely-constructed web
. When alarmed, it will sit along a plant stem, a blade of grass
or the central vein of a leaf
, with its four front legs pointing forwards, and its four back legs pointing backwards for camouflage
. T. extensa is able to walk on the surface of water, where it can move faster than on land.
, and the male and female lock jaws, possibly to prevent the female from eating the male before mating. The egg sacs are globular and covered with grey tufted silk
, resembling a bird dropping
, and are pressed against a plant stem. Overwintering occurs in the form of early-instar
spiderlings.
by Carl Linnaeus in his Systema Naturae
of 1758, the starting point of zoological nomenclature. In that work, it was included in the genus Aranea (now Araneus
). T. extensa is a very common, widespread and variable species, and a number of synonyms
have been published:
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 spider
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...
found across the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. It has an elongate body, up to 11 mm (0.433070866141732 in) long, and adopts a straight line posture when alarmed. It lives on low vegetation in damp areas, and feeds on flying insects which it catches in its web.
Description
T. extensa has an elongated, cream-coloured body. Males are smaller than females, at around 9 millimetre (0.354330708661417 in) body length, compared to 11 mm (0.433070866141732 in) for females. The four pairs of legs are very long, and are dark yellow. The carapace, which is around 1.8–2.6 mm long and 1.1–1.7 mm wide, is orange or dark yellow.Distribution
T. extensa has a wide distribution across the Northern HemisphereNorthern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. In North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, it is found from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to Newfoundland, and its range extends south to Washington, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
and Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
. The species has a broad ecological range, having been found at the tree line in the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
and in coastal vegetation in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. T. extensa is found throughout the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, where it is the commonest species of Tetragnatha
Tetragnatha
Tetragnatha is a genus of spiders containing hundreds of species. They are found all over the world, although most occur in the tropics and subtropics. They are commonly called stretch spiders, referring to their elongated body form...
, and one of the commonest spiders. The colouring of T. extensa is quite variable, ranging from creamy-yellow to green. On the underside, there is a thick black central band, with a silvery band on either side.
T. extensa is distinguished from other members of the genus Tetragnatha
Tetragnatha
Tetragnatha is a genus of spiders containing hundreds of species. They are found all over the world, although most occur in the tropics and subtropics. They are commonly called stretch spiders, referring to their elongated body form...
by the minute curved tip of the male's conductor (part of the pedipalp
Pedipalp
Pedipalps , are the second pair of appendages of the prosoma in the subphylum Chelicerata. They are traditionally thought to be homologous with mandibles in Crustacea and insects, although more recent studies Pedipalps (commonly shortened to palps or palpi), are the second pair of appendages of the...
), and the form of the female's spermatheca
Spermatheca
The spermatheca , also called receptaculum seminis , is an organ of the female reproductive tract in insects, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates...
.
Ecology and behaviour
Tetragnatha extensa is found on low-growing vegetation, usually in damp areas. It feeds on insectInsect
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...
s, including mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
s, midge
Midge
A midge is a very small, two-winged flying insect. "Midge" may also refer to:-Real:* Midge Costanza , American politician* Mildred Gillars , aka "Midge", American broadcaster of Nazi propaganda during World War II...
s and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s, which it catches in its loosely-constructed web
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....
. When alarmed, it will sit along a plant stem, a blade of grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
or the central vein of a leaf
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, with its four front legs pointing forwards, and its four back legs pointing backwards for camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
. T. extensa is able to walk on the surface of water, where it can move faster than on land.
Life cycle
Adults are seen between May and September in the United Kingdom, and between May and July in Alaska. There is little courtshipCourtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
, and the male and female lock jaws, possibly to prevent the female from eating the male before mating. The egg sacs are globular and covered with grey tufted 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...
, resembling a bird dropping
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
, and are pressed against a plant stem. Overwintering occurs in the form of early-instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
spiderlings.
Taxonomic history
Tetragnatha extensa was first given a binomialBinomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
by Carl Linnaeus in his Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
of 1758, the starting point of zoological nomenclature. In that work, it was included in the genus Aranea (now Araneus
Araneus
Araneus is a genus of common orb-weaving spiders. It includes about 650 species, among which are the European garden spider and the barn spider.-Description:...
). T. extensa is a very common, widespread and variable species, and a number of synonyms
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
have been published:
- Aranea extensa Linnaeus, 1758
- Aranea solandri Scopoli, 1763
- Aranea mouffeti Scopoli, 1763
- Tetragnatha rubra Risso, 1826
- Tetragnatha gibba C. L. Koch, 1837
- Tetragnatha chrysochlora Walckenaer, 1841
- Tetragnatha arundinis Bremi-Wolff, 1849
- Tetragnatha fluviatilis Keyserling, 1865
- Tetragnatha nowickii L. Koch, 1870
- Tetragnatha groenlandica Thorell, 1872
- Tetragnatha solandri (Scopoli, 1763)
- Tetragnatha manitoba Chamberlin & Ivie, 1942
- Tetragnatha rusticana Chickering, 1959
- Tetragnatha potanini Schenkel, 1963
- Tetragnatha maderiana Wunderlich, 1987