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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 close kin), where they point straight down. Araneomorphs comprise the vast majority of living spiders. Distinguishing characteristics Most spider species are Araneomorphae, which have fangs that face towards each other, increasing the orientations they can employ during prey capture. They have fewer book lungs (when present), and the females typically live one year. The Mygalomorphae have fangs that face towards the ground, and which are parallel to the long axis of the spider's body, thus they have only one orientation they can employ during prey capture. They have four pairs of book lungs, and the females often live many years. Image:Atrax robustus.jpg, This '' Atrax robustus'' shows the orientation of Myglamorphae fangs. Image:Che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synspermiata
Synspermiata is a clade of araneomorph spiders, comprising most of the former " haplogynes". They are united by having simpler genitalia than other araneomorph spiders, lacking a cribellum, and sharing an evolutionary history of synspermia – a particular way in which spermatozoa are grouped together when transferred to the female. Synspermia Spermatozoa are produced in a multi-step process. A primary spermatocyte with the full diploid number of chromosomes divides to form two secondary spermatocytes which are haploid, i.e. each has half the diploid number of chromosomes. Each secondary spermatocyte then divides to produce two spermatids which undergo further development to form spermatozoa. In synspermia, two or more spermatids from the same spermatocyte fuse together and are enclosed in an envelope, forming a "capsule". This contrasts with cleistospermia, where the capsules enclose individual spermatozoa. After transfer to the female in either form, decapsulation and activati ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypochilidae
Lampshade spiders, family Hypochilidae, are among the most primitive of araneomorph spiders. There are two genus, genera and twelve species currently recognized. Like mygalomorphs, most hypochilids have two pairs of book lungs, but like araneomorphs they have intersecting fangs, with the exception of some species which have chelicerae in an angle that is neither orthognathous or labidognathous. These long-legged spiders build typical "lampshade" style webs under overhangs and in caves. In the United States the fauna is primarily associated with the Appalachian Mountains, Appalachian, Rocky Mountains, Rocky and California Mountains. Ten of the known species are found in these ranges, all in the genus ''Hypochilus''. The genus ''Ectatosticta'' is found in China. In one analysis, the Hypochilidae are a sister clade to the Neocribellatae, which contains all other spider species in the Araneomorphae (Coddington & Levi, 1991, p. 576). A more recent study groups them with the Haplog ... [...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 relea ... [...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 br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spider
Spiders (order Araneae) are air-breathing arthropods that have eight legs, 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 for Antarctica, and have become established in nearly every land habitat. , 50,356 spider species in 132 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. Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body segments are fused into two tagmata, the cephalothorax or prosoma, and the opisthosoma, or abdomen, and joined by a small, cylindrical pedicel, however, as there is currently neither paleontological nor embryological evidence that spiders ever had a sep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tangle Web Spider
Theridiidae, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders, is a large family of araneomorph spiders first described by Carl Jakob Sundevall in 1833. This diverse, globally distributed family includes over 3,000 species in 124 genera, and is the most common arthropod found in human dwellings throughout the world. Theridiid spiders are both entelegyne, meaning that the females have a genital plate, and ecribellate, meaning that they spin sticky capture silk instead of woolly silk. They have a comb of serrated bristles (setae) on the tarsus of the fourth leg. The family includes some model organisms for research, including the medically important widow spiders. They are important to studies characterizing their venom and its clinical manifestation, but widow spiders are also used in research on spider silk and sexual biology, including sexual cannibalism. ''Anelosimus'' are also model organisms, used for the study of sociality, because it has evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austrochiloidea
The Austrochiloidea or austrochiloids are a group of araneomorph spiders, treated as a superfamily. The taxon contains two families of eight-eyed spiders: * Austrochilidae Zapfe, 1955 * Gradungulidae Forster, 1955 Phylogeny The monophyly of the Austrochiloidea has been supported in both morphological and molecular phylogenetic studies. The position of the clade relative to two much larger groups, Haplogynae and 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; m ..., has varied. A summary in 2005 showed the Austrochiloidea to be basal to both groups: Two studies have placed representatives of the Austrochiloidea between the two, suggesting they have more derived characters than previously supposed: References {{Taxonbar, from=Q54482 Araneomorphae Arachnid super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palpimanoidea
The Palpimanoidea or palpimanoids, also known as assassin spiders, are a group of araneomorph spiders, originally treated as a superfamily. As with many such groups, its circumscription has varied. , the following five families were included: * Archaeidae * Huttoniidae * Mecysmaucheniidae * Palpimanidae * Stenochilidae Many palpimanoids specialize in preying on other spiders, hence the name "assassin spiders". They have various adaptations for catching prey, including enlarged spade-like front legs, and heads raised up on a "neck" with long chelicerae ("jaws"). Fossils suggest that the group was once widespread, but most species are now found in the Southern Hemisphere. Morphological studies support the monophyly of the group, although molecular studies have produced different results. Description Many palpimanoids, particularly members of the families Archaeidae, Huttoniidae and Stenochilidae, specialize in preying on other spiders, hence the description "assassin spiders". T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jumping Spider
Jumping spiders are a group of spiders that constitute the family Salticidae. As of 2019, this family contained over 600 described genera and over 6,000 described species, making it the largest family of spiders at 13% of all species. Jumping spiders have some of the best vision among arthropods and use it in courtship, hunting, and navigation. Although they normally move unobtrusively and fairly slowly, most species are capable of very agile jumps, notably when hunting, but sometimes in response to sudden threats or crossing long gaps. Both their book lungs and tracheal system are well-developed, and they use both systems (bimodal breathing). Jumping spiders are generally recognized by their eye pattern. All jumping spiders have four pairs of eyes, with the anterior median pair being particularly large. Distinguishing characteristics Jumping spiders are among the easiest to distinguish from similar spider families because of the shape of the cephalothorax and their eye patt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Phylogenetics
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to determine the processes by which diversity among species has been achieved. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree. Molecular phylogenetics is one aspect of molecular systematics, a broader term that also includes the use of molecular data in taxonomy and biogeography. Molecular phylogenetics and molecular evolution correlate. Molecular evolution is the process of selective changes (mutations) at a molecular level (genes, proteins, etc.) throughout various branches in the tree of life (evolution). Molecular phylogenetics makes inferences of the evolutionary relationships that arise due to molecular evolution and results in the construction of a phylogenetic tree. History The theoretical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Series (biology)
In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system consists of species, genus, family, order, class, phylum, kingdom, domain. While older approaches to taxonomic classification were phenomenological, forming groups on the basis of similarities in appearance, organic structure and behaviour, methods based on genetic analysis have opened the road to cladistics. A given rank subsumes under it less general categories, that is, more specific descriptions of life forms. Above it, each rank is classified within more general categories of organisms and groups of organisms related to each other through inheritance of traits or features from common ancestors. The rank of any ''species'' and the description of its ''genus'' is ''basic''; which means that to identify a particular organism, it is usually not necessary to specify ranks other than these first two. Consider a particu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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