|
Cribellum
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 po ... [...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] |
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] |
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] |
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] |
Mygalomorphae
The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to them forming trapdoors over their burrows. Other prominent groups include Australian funnel web spiders and tarantulas, with the latter accounting for around one third of all mygalomorphs. Description This group of spiders comprises mostly heavy-bodied, stout-legged spiders including tarantulas, Australian funnel-web spiders, mouse spiders, and various families of spiders commonly called trapdoor spiders. Like the " primitive" suborder of spiders Mesothelae, they have two pairs of book lungs, and downward-pointing chelicerae. Because of this, the two groups were once believed to be closely related. Later it was realized that the common ancestors of all spiders had these features (a state known as symplesiomorphy). Following the branching ... [...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] |
Israel Journal Of Entomology
The ''Israel Journal of Entomology'' is an open access peer-reviewed scientific journal that publishes articles in all areas of entomology, including besides insects non-marine Crustacea and Chelicerata, and has a worldwide scope. The ''Israel Journal of Entomology'' is published primarily electronically and accepts original research articles, as well as review papers and smaller contributions. The printed version of the ''Israel Journal of Entomology'' is produced annually and comprises articles appeared during the preceding year. History The ''Israel Journal of Entomology'' was established in 1966 thus having a continuous history of 50 years. All published issues are freely available in digital form through the Entomological Society of Israel website. Scope A wide range of entomological topics has been covered in the ''Israel Journal of Entomology''. Besides taxonomy and systematics of various insects and arachnids, papers dealing with medical and agricultural entomology, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenidae
Wandering spiders (''Ctenidae'') are a family of spiders that includes the Brazilian wandering spiders. These spiders have a distinctive longitudinal groove on the top-rear of their oval carapace similar to those of the Amaurobiidae. They are highly defensive and venomous nocturnal hunters. Wandering spiders are known to hunt large prey, for example hylid species '' Dendropsophus branneri.'' Despite their notoriety for being dangerous, only a few members of ''Phoneutria'' have venom known to be hazardous to humans, but the venoms of this family are poorly known, so all larger ctenids should be treated with caution. Genera , the World Spider Catalog accepts the following genera: *'' Acantheis'' Thorell, 1891 — Asia *'' Acanthoctenus'' Keyserling, 1877 — South America, Central America, Jamaica, Mexico *'' Africactenus'' Hyatt, 1954 — Africa, India *'' Afroneutria'' Polotow & Jocqué, 2015 — Africa *'' Amauropelma'' Raven, Stumkat & Gray, 2001 — Asia, Australia *'' Amicac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphinectidae
Desidae is a family of spiders, some of which are known as intertidal spiders. The family is named for the genus '' Desis'', members of which live in a very unusual location — between the tides. The family has been reevaluated in recent years and now includes inland genera and species as well, such as ''Badumna'' and ''Phryganoporus''. In 2017, the family Amphinectidae was merged into Desidae. The family Toxopidae has been separated off. Those intertidal spiders that are truly marine commonly live in barnacle shells, which they seal up with silk; this allows them to maintain an air bubble during high tide. They emerge at night to feed on various small arthropods that live in the intertidal zone. Distribution As now circumscribed, the family Desidae is mainly found in South America and Australasia, with some species reaching north to Malaysia. ''Metaltella simoni'' has been introduced in a large part of the Southern United States (records exist from California, Louisiana, Mississ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agelenidae
The Agelenidae are a large family of spiders in the suborder Araneomorphae. Well-known examples include the common "grass spiders" of the genus ''Agelenopsis''. Nearly all Agelenidae are harmless to humans, but the bite of the hobo spider (''Eratigena agrestis'') may be medically significant, and some evidence suggests it might cause necrotic lesions, but the matter remains subject to debate. The most widely accepted common name for members of the family is funnel weaver. Description The body length of the smallest Agelenidae spiders are about , excluding the legs, while the larger species grow to long. Some exceptionally large species, such as ''Eratigena atrica'', may reach in total leg span. Agelenids have eight eyes in two horizontal rows of four. Their cephalothorax, cephalothoraces narrow somewhat towards the front where the eyes are. Their abdomens are more or less oval, usually patterned with two rows of lines and spots. Some species have longitudinal lines on the dorsa ... [...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] |
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] |
