In spiders, the calamistrum is a row of specialized leg bristles used to comb out fine bands of silk. [1] It is only found on cribellate spiders, that is, spiders that possess the spinning organ known as the cribellum. [2] The calamistrum and cribellum are used to form the hackled bands of silk which are characteristic of the webs of these spiders. [2] The calamistrum is found on the upper margin of the metatarsus of the hind legs. [2] Each bristle of the calamistrum is serrated on one side and smooth on the other. [1]
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. [3]
When male cribellate spiders reach sexual maturity, they either lose the cribellum and calamistrum or retain them in a vestigial form. [2]
Uloboridae is a family of non-venomous spiders, known as cribellate orb weavers or hackled orb weavers. Their lack of venom glands is a secondarily evolved trait. Instead, they wrap their prey thoroughly in silk, cover it in regurgitated digestive enzymes, and then ingest the liquified body.
Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name of the group. Araneids have eight similar eyes, hairy or spiny legs, and no stridulating organs.
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, 2023, the family Amaurobiidae includes 286 species in 50 genera.
Zoropsidae, also known as false wolf spiders for their physical similarity to wolf spiders, is a family of cribellate araneomorph spiders first described by Philipp Bertkau in 1882. They can be distinguished from wolf spiders by their two rows of eyes that are more equal in size than those of Lycosidae.
Cribellum literally means "little sieve", and in biology the term generally applies to anatomical structures in the form of tiny perforated plates.
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.
Oecobius navus is a small cosmopolitan cribellate spider species found across the world.
The anatomy of spiders includes many characteristics shared with other arachnids. These characteristics include bodies divided into two tagmata, eight jointed legs, no wings or antennae, the presence of chelicerae and pedipalps, simple eyes, and an exoskeleton, which is periodically shed.
Uloborus plumipes is a species of Old World cribellate spider in the family Uloboridae. Common names include the feather-legged lace weaver and the garden centre spider, the latter name being due to its frequent occurrence of this spider in garden centres. The species name is derived from the Latin pluma "feather" and pes "foot".
Titanoeca quadriguttata is a species of spider in the family Titanoecidae. It is widespread in Europe, though absent from Great Britain, and is found in Austria, Belgium, Bulgaria, Corsica, Croatia, Czech Republic, France, Germany, Greece, Hungary, Italy, Liechtenstein, Moldova, Russia, Slovakia, Spain, Switzerland, the Netherlands, Ukraine.
Maevia inclemens or the dimorphic jumping spider is a relatively common and colorful jumping spider of North America. In the males there are two forms, a very rare phenomenon in zoology. These use different courting displays, and differ in appearance: the "tufted" morph has a black body and pedipalps ("palps"), three black tufts across its "head", and pale legs; and the "gray" morph has black and white stripes all over its body and legs, orange palps, and no tufts. However, each form accounts for 50% of the adult males, and they are equally successful in mating. A female of Maevia inclemens is 6.5 to 8.0 millimetres long, while males are 4.75 to 6.50 millimetres long.
Tarantulas comprise a group of large and often hairy spiders of the family Theraphosidae. As of December 2023, 1,100 species have been identified, with 166 genera. The term "tarantula" is usually used to describe members of the family Theraphosidae, although many other members of the same infraorder (Mygalomorphae) are commonly referred to as "tarantulas" or "false tarantulas". Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have setae known as urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.
Spiders are air-breathing arthropods that have eight limbs, 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 Antarctica, and have become established in nearly every land habitat. As of November 2023, 51,673 spider species in 136 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.
This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids.
Mongolarachne is an extinct genus of spiders placed in the monogeneric family Mongolarachnidae. The genus contains only one species, Mongolarachne jurassica, described in 2013, which is presently the largest fossilized spider on record. The type species was originally described as Nephila jurassica and placed in the living genus Nephila which contains the golden silk orb-weavers.
Progradungula otwayensis, commonly known as the odd-clawed spider, is a species of cribellate spider endemic to the Great Otway National Park of Victoria, Australia. It is one of only two species in the gradungulid genus Progradungula.
Hyptiotes paradoxus, also known as the triangle spider, is a cribellate orbweaver in the family Uloboridae.
Hypochilus thorelli is a species of spider in the family Hypochilidae. Unlike almost all other araneomorph or "true" spiders, members of the family have four book lungs. They are often called "lampshade spiders" because of the shape of their webs which are usually built underneath ledges or projections. H. thorelli is found in the southern Appalachian Mountains of the eastern United States.
Orbiculariae is a potential clade of araneomorph spiders, uniting two groups that make orb webs. Phylogenetic analyses based on morphological characters have generally recovered this clade; analyses based on DNA have regularly concluded that the group is not monophyletic. The issue relates to the origin of orb webs: whether they evolved early in the evolutionary history of entelegyne spiders, with many groups subsequently losing the ability to make orb webs, or whether they evolved later, with fewer groups having lost this ability. As of September 2018, the weight of the evidence strongly favours the non-monophyly of "Orbiculariae" and hence the early evolution of orb webs, followed by multiple changes and losses.
Mexcala macilenta is a species of jumping spider in the genus Mexcala that lives in Ethiopia and Tanzania. The spider was first defined in 2000 by Wanda Wesołowska and Anthony Russell-Smith. It mimics ants and ant-like wasps, living alongside and preying upon them. The spider is medium-sized to large, with a brown carapace between 3.2 and 3.4 mm long and a rusty-brown or greyish-russet abdomen between 3.2 and 5.5 mm long. The female is larger than the male. Both male and females have long thin brown legs and a distinctive pattern of a large triangular black marking in the middle of the abdomen. The male copulatory organs have a thin tibial apophysis and lack the triangular lobe on the palpal bulb that other species in the genus possess.