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Palpal Bulb
The two palpal bulbs – also known as palpal organs and genital bulbs – are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps (the front "limbs" of a spider), giving the spider an appearance often described as like wearing boxing gloves. The palpal bulb does not actually produce sperm, being used only to transfer it to the female. Palpal bulbs are only fully developed in adult male spiders and are not completely visible until after the final moult. In the majority of species of spider, the bulbs have complex shapes and are important in identification. Structure The palpal bulb of a mature male spider is borne on the last segment of the pedipalp. This segment usually has touch-sensitive hairs (setae) with nerves leading to them. The bulb itself is entirely without nerves, and hence without sensory organs and muscles, since these depend on nerves for their functioning, although some spiders have one or two muscles external to the bulb an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheiracanthium Mildei Male
''Cheiracanthium'', commonly called ''yellow sac spiders'', is a genus of araneomorph spiders in the family Cheiracanthiidae, and was first described by Carl Ludwig Koch in 1839. They are usually pale in colour, and have an abdomen that can range from yellow to beige. Both sexes range in size from . They are unique among common house spiders because their tarsi do not point either outward, like members of ''Tegenaria'', or inward, like members of ''Araneus''), making them easier to identify. The name is a reference to the backwardly directed process on the cymbium of the male palp. The species epithet is derived from the Greek grc, χείρ, cheir, meaning "hand", and '' Acanthium'', a genus of thorny-stemmed plants. Venom Though they are beneficial predators in agricultural fields, they are also known to be mildly venomous to humans. Painful bites may be incurred from species such as '' C. punctorium'' in Europe, '' C. mildei'' in Europe and North America, '' C. inclusum' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deinopis
''Deinopis'', also known as net-casting spiders, gladiator spiders and ogre-faced spiders, is a genus of net-casting spiders that was first described by W. S. MacLeay in 1839. Its distribution is widely tropical and subtropical. They catch their prey using a specially spun "net". The name is derived from the Greek (''deinos''), meaning "fearful", and ''opis'', meaning "appearance", referring to their ogre-like faces. The spelling "''Dinopis''" is also found, but is regarded as an "unjustified emendation". Net-casting Spiders in the genus ''Deinopis'' catch their prey in an unusual fashion. They first spin a small upright rectangular cribellate web. This is then detached from its supporting threads and held horizontally above the ground by the spider's long front two pairs of legs while the spider hangs almost vertically. Passing prey is then captured by dropping the "net" over it. Eyes The two posterior median eyes are enlarged and forward-facing. These eyes have a wide field ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete (e.g., egg and sperm fusing). In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea and parasitic wasps) and a few vertebrates (such as some fish, amphibians, reptiles and birds). This type of reproduction has been induced artificially i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigyne
The epigyne or epigynum is the external genital structure of female spiders. As the epigyne varies greatly in form in different species, even in closely related ones, it often provides the most distinctive characteristic for recognizing species. It consists of a small, hardened portion of the exoskeleton located on the underside of the abdomen, in front of the epigastric furrow and between the epigastric plates. Functions The primary function of the epigyne is to receive and direct the palpal organ of the male during copulation. The various specific forms of epigynes are correlated, in each case, with corresponding specific differences in the palpus of the male. This specialization prevents individuals of different species from mating. The epigyne covers or accompanies the openings of the spermathecae, which are pouches for receiving and retaining sperm. Frequently, the openings of the spermathecae are on the outer face of the epigyne and can be easily seen. A secondary functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicorn Catleyi Copulatory Bulb
The unicorn is a legendary creature that has been described since antiquity as a beast with a single large, pointed, spiraling horn projecting from its forehead. In European literature and art, the unicorn has for the last thousand years or so been depicted as a white horse-like or goat-like animal with a long straight horn with spiralling grooves, cloven hooves, and sometimes a goat's beard. In the Middle Ages and Renaissance, it was commonly described as an extremely wild woodland creature, a symbol of purity and grace, which could be captured only by a virgin. In encyclopedias, its horn was described as having the power to render poisoned water potable and to heal sickness. In medieval and Renaissance times, the tusk of the narwhal was sometimes sold as a unicorn horn. A bovine type of unicorn is thought by some scholars to have been depicted in seals of the Bronze Age Indus Valley civilization, the interpretation remaining controversial. An equine form of the unicorn was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomisus Spectabilis
''Thomisus spectabilis'', also known as the white crab spider or Australian crab spider, is a small spider found in Australia and far east Asia. The body length of the female is up to 10 mm, the male 6.2 mm. Including legs, the spider is around 3 cm across.Australian Spiders in Colour - Ramon Mascord 1970 SBN 589 07065 7, page 48 This spider is usually white, though sometimes may appear yellow. The legs and head appear almost translucent. ''Thomisus spectabilis'' is an ambush predator, often seen resting in flowers of its same color. Its egg sacs are laid in a folded leaf, and the cream colored eggs, typically 1 mm in diameter, range between 200 and 370 in number. These spiders primarily eat insects and their preference for symmetry helps them in capturing pollinating insects such as butterflies and bees.Astrid M. Heiling, Ken Cheng, Marie E. Herberstein, Exploitation of floral signals by crab spiders (''Thomisus spectabilis'', Thomisidae), ''Behavioral Ecol ... [...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 t ... [...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] |
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. The genus was erected by Carl Alexander Clerck in 1757. Description Spiders of this genus present perhaps the most obvious case of sexual dimorphism among all of the orb-weaver family, with males being normally to the size of females. In ''A. diadematus'', for example, last-molt females can reach the body size up to 1 in (2.5 cm), while most males seldom grow over 0.3 in (1 cm), both excluding leg span. Males are differentiated from females by a much smaller and more elongated abdomen, longer legs, and the inability to catch or consume prey bigger than themselves. In females, the epigyne has a long scape (a tongue-like appendage). Male pedipalps have a hook-like terminal apophysis. Abdominal tubercles are present anterolaterally. Taxonomic history ''Araneus'' was, for much of its history, called ''Epeira'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agelenopsis
''Agelenopsis'', commonly known as the American grass spiders, is a genus of funnel weavers first described by C.G. Giebel in 1869. They weave sheet webs that have a funnel shelter on one edge. The web is not sticky, but these spiders make up for that shortcoming by running very rapidly. The larger specimens (depending on species) can grow to about 19 mm in body length. They may be recognized by the arrangement of their eight eyes into three rows. The top row has two eyes, the middle row has four eyes, and the bottom row has two eyes (spaced wider than the ones on the top row). They have two prominent hind spinnerets, somewhat indistinct bands on their legs, and two dark bands running down either side of the cephalothorax. Name The genus name is a combination of '' Agelena'' (Eurasian grass spiders), a genus of similar spiders, and Greek ''-opsis'' "to look like". They are harmless spiders. Although most spiders use their webs to catch prey, the grass spider's web lacks a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonopore
A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female it is the opening of the common oviduct, and in the male, it is the opening of the ejaculatory duct. The position of the gonopore varies considerably between groups, but is generally constant within groups, allowing its position to be used as a "segmental marker". In Malacostraca, it is on the sixth thoracic segment; in Symphyla it is on the fourth trunk segment; in arachnids, it is on the second segment of the opisthosoma. In insects and centipedes, the gonopores are close to the animal's tail, while in millipedes they are on the third body segment behind the head, near the second pair of legs. See also * Gonopod Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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