|
Cribellate
Cribellum literally means "little sieve", and in biology the term generally applies to anatomical structures in the form of tiny perforated plates. In certain groups of diatoms it refers to microscopically punctured regions of the frustule, or outer layer. In certain groups of spider species, so-called cribellate spiders, the cribellum is a silk spinning organ. Unlike the usual spinnerets of spiders, the cribellum consists of one or more plates covered in thousands of tiny spigots, tiny holes that hardly project from the surface, in contrast to the elongated spigots that project from spinnerets. These minute spigots produce extremely fine fibers, merely tens of nanometres thick, which are combed out by the spider's calamistrum, producing silk with a woolly texture. The fibers are so small in diameter that they are strongly subject to Van der Waals forces. In addition, the fibres have a surface that absorbs waxes from the epicuticle of insect prey on contact. This creates a pow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Progradungula Otwayensis Immature Male With Catching Ladder
''Progradungula'' is a genus of Australian large-clawed spiders that was first described by Raymond Robert Forster & Michael R. Gray in 1979. it contains only two species: '' P. carraiensis'' and '' P. otwayensis''. The name is derived from Latin ''pro'' ("before"), and the genus name ''Gradungula'', referring to the ancient ancestry of the genus. It is the first discovered web-building cribellate spider in a "primitive" araneomorph The Araneomorphae (also called the Labidognatha) are an infraorder of spiders. They are distinguishable by chelicerae (fangs) that point diagonally forward and cross in a pinching action, in contrast to the Mygalomorphae (tarantulas and their cl ... spider family and helped establish the idea that all araneomorph spiders evolved from cribellate ancestors. These spiders have an uncommon web-making technique and prey-capturing behavior. A small (approximately 25 by 6 mm), tilting, ladder-like platform of cribellate capturing silk is supported by a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deinopoidea
The Deinopoidea or deinopoids are group of cribellate araneomorph spiders that may be treated as a superfamily. As usually circumscribed, the group contains two families: Deinopidae and Uloboridae. Some studies have produced cladograms in which the Deinopoidea are paraphyletic. A review in 2014 concluded that "at this time the monophyly of Deinopoidea remains dubious". Characteristics The group is characterized by the production of orb webs with catching threads of cribellate silk (i.e. silk made up of very fine threads produced by combing an initial thread using the spider's calamistrum). Uloborids spin vertical orb webs, very similar in shape to those made by araneids, such as the cross spider. Deinopids initially spin an orb web, which they then suspend between their front legs and use as a net to ensnare prey. Phylogeny According to one hypothesis, the two groups in which orb-weaving occurs, the cribellate deinopoids and the ecribellate araneoids, make up a single monophyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amaurobius Ferox
''Amaurobius ferox'', sometimes known as the black lace-weaver, is a common nocturnal spider belonging to the family ''Amaurobiidae'' and genus '' Amaurobius''. Its genus includes the permanently social species ''A. socialis'', and three subsocial species, ''A. fenestralis, A. similis'' and ''A. ferox'', all three of which have highly developed subsocial organizations. Description Females of this species range from around 11–16 mm in body length, while males are slightly smaller and more slender, ranging from 8–10 mm. The spider is very dark in color with its primary shades being black, brown, dark red, and tan. The abdomen is rounded and has light yellow pale markings in a unique pattern that is often described as resembling a ghoulish mask or skull pattern. Habitat and distribution ''A. ferox'' is usually found near man-made structures. The species prefers dark areas, such as underneath logs or inside cellars, and it often likes to live in moist, shaded crevi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entelegynae
The Entelegynae or entelegynes are a subgroup of araneomorph spiders, the largest of the two main groups into which the araneomorphs were traditionally divided. Females have a genital plate ( epigynum) and a "flow through" fertilization system; males have complex palpal bulbs. Molecular phylogenetic studies have supported the monophyly of Entelegynae (whereas the other traditional subgroup, the Haplogynae, has been shown not to be monophyletic). The clade contains both cribellate and ecribellate spiders. Characterization The Entelegynae are characterized primarily by the nature of the female genital system. The ancestral ( plesiomorphic) system is found in non-entelegyne spiders, where there is a single external genital opening in the female's abdomen. One or more males inject sperm from their palpal bulbs via this opening; the sperm is usually stored in special spermathecae (absent in some spiders, e.g. ''Pholcus''). When eggs are released from the ovaries, sperm is also releas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplogynae
The Haplogynae or haplogynes are one of the two main groups into which araneomorph spiders have traditionally been divided, the other being the Entelegynae. Morphological phylogenetic studies suggested that the Haplogynae formed a clade; more recent molecular phylogenetic studies refute this, although many of the ecribellate haplogynes do appear to form a clade, Synspermiata. Unlike the Entelegynae, haplogynes lack hardened (sclerotized) female genitalia (epigynes). Most of the species within this group have six eyes, as opposed to most other spiders. Spiders in the genus '' Tetrablemma'' (Tetrablemmidae) have only four eyes, as do some members of the family Caponiidae; caponiids may even have only two eyes. However, spiders in the family Plectreuridae have the normal eight eyes. Phylogeny The Haplogynae are one of the two major groups into which araneomorph spiders were traditionally divided, the other being the Entelegynae. In 2005, Coddington summarized the relationships of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amaurobiidae
''Amaurobiidae'' is a family of three-clawed cribellate or ecribellate spiders found in crevices and hollows or under stones where they build retreats, and are often collected in pitfall traps. Unlidded burrows are sometimes quite obvious in crusty, loamy soil. They are difficult to distinguish from related spiders in other families, especially Agelenidae, Desidae and Amphinectidae. Their intra- and interfamilial relationships are contentious. According to the World Spider Catalog, 2019, the family Amaurobiidae includes about 275 species in 49 genera. In Australia, they are small to medium-sized entelegyne spiders with minimal sheet webs. They are fairly common in Tasmania and nearby mainland Australia in cooler rainforest, some in caves. They are widespread but uncommon along the eastern coastline. They generally have eight similar eyes in two conservatively curved rows. They often have a calamistrum on metatarsus IV associated with a cribellum. Australian amaurobiids may be dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calamistrum
In spiders, the calamistrum is a row of specialized leg bristles used to comb out fine bands of silk. It is only found on cribellate spiders, that is, spiders that possess the spinning organ known as the cribellum. The calamistrum and cribellum are used to form the hackled bands of silk which are characteristic of the webs of these spiders. The calamistrum is found on the upper margin of the metatarsus of the hind legs. Each bristle of the calamistrum is serrated on one side and smooth on the other. The length of a spider's calamistrum is always equal to or greater than the width of the cribellum. The ratio between calamistrum length and cribellum width varies greatly, however, even among related species. This is likely due to differences in spinning behavior and as well as differences in the size and shape of the legs and abdomen. When male cribellate spiders reach sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filistatidae
Crevice weaver spiders (Filistatidae) comprise cribellate spiders with features that have been regarded as " primitive" for araneomorph spiders. They are weavers of funnel or tube webs. The family contains 18 genera and more than 120 described species worldwide. One of the most abundant members of this family in the Americas is the southern house spider (''Kukulcania hibernalis''). Named after the fierce Meso-American god Kukulkan, the females are large (up to nearly 20 mm) dark-colored spiders and males are light brown, smaller (about 10 mm), but more long-legged and with palps that are held together in front of their carapaces like the horn of a unicorn. The males also have a darker streak on the center of the dorsal carapace that causes them to be often mistaken for brown recluse spiders. The tiny members of the genus ''Filistatinella'' are like miniature versions of ''Kukulcania''. The nominate genus ''Filistata'' is Afro-Eurasian in distribution. In many older boo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Araneoidea
Araneoidea is a taxon of araneomorph spiders, termed "araneoids", treated as a superfamily. As with many such groups, its circumscription has varied; in particular some families that had at one time moved to the Palpimanoidea have more recently been restored to Araneoidea. A 2014 treatment includes 18 families, with the araneoids making up about 26% of the total number of known spider species; a 2016 treatment includes essentially the same taxa, but now divided into 17 families. Taxonomy Many of the differences in circumscription concern the relationship between Araneoidea and Palpimanoidea. In 1984, Raymond R. Forster and Norman I. Platnick proposed that some groups previously considered araneoid actually belonged in the distantly related Palpimanoidea, including the families Holarchaeidae, Micropholcommatidae, Mimetidae and Pararchaeidae. Subsequent phylogenetic studies have rejected this proposal, firmly placing these four families in Araneoidea (some included in other famil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austrochilidae
Austrochilidae is a small spider family with nine species in two genera. ''Austrochilus'' and ''Thaida'' are endemic to the Andean forest of central and southern Chile and adjacent Argentina. Taxonomy , two genera are placed in the family Austrochilidae: ''Austrochilus'' and ''Thaida'', found in Chile and Argentina. The taxonomic placement of these genera has varied. In 1968, Lehtinen synonymized ''Austrochilus'' and ''Thaida'' under the latter name, placing the genus in a family he called "Thaididae". However, the family name "Thaididae" is preoccupied, being first used for a family of gastropods in 1887. A single family was accepted by Forster ''et al''. in 1987, under the name "Austrochilidae". Molecular phylogenetic studies agree in placing the two genera as basal members of the Araneomorphae, although the precise details and the family placement are not yet agreed. Phylogeny One hypothesis for the phylogeny of the genera placed in the family is shown below (Austrochilidae g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deinopidae
Deinopidae, also known as net casting spiders, is a family of cribellate spiders first described by Carl Ludwig Koch in 1850. It consists of stick-like elongated spiders that catch prey by stretching a web across their front legs before propelling themselves forward. These unusual webs will stretch two or three times their relaxed size, entangling any prey that touch them. The posterior median eyes have excellent night vision, allowing them to cast nets accurately in low-light conditions. These eyes are larger than the others, and sometimes makes these spiders appear to only have two eyes. Ogre-faced spiders (''Deinopis'') are the best known genus in this family. The name refers to the perceived physical similarity to the mythological creature of the same name. This family also includes the humped-back spiders (''Menneus''). They are distributed through tropics worldwide from Australia to Africa and the Americas. In Florida, ''Deinopis'' often hangs upside down from a silk line und ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod Cuticle
The cuticle forms the major part of the integument of the Arthropoda. It includes most of the material of the exoskeleton of the insects, Crustacea, Arachnida, and Myriapoda. Morphology In arthropods, the integument, the external "skin", or "shell", is the product of a single layer of ectodermal epithelium. That layer is attached to the external or distal surface of the deepest layer, the non-cellular internal membrane of the integument. That non-cellular membrane is called the basement membrane. The layer of epithelium on the basement membrane produces the cuticle, which begins as a tough, flexible layer of chitin. Such thin, flexible chitin is the major structural part of the integument where flexibility is necessary, such as in bodily parts that must stretch to contain accumulated liquids, or that form joints between rigid parts of the exoskeleton. In other parts of the cuticle the function of the integument demands more rigid materials, such as armoured regions or the biting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Amaurobius Ferox")
