May 03, 2020 · «Phalangium opilio es una de las especies recolectoras más extendidas del mundo y se puede ver fácilmente en las ciudades. Uno de los conceptos erróneos más grandes es que son venenosos, pero son demasiado ‘débiles’ para infligir un mordisco «, dijo, y agregó que los arácnidos no tienen veneno ni muerden.
- Antipredator Defenses
- Endangered Status
- Fossil Record
The Opiliones are known for having exceptionally long legs relative to their body size; however, some species are short-legged. As in all Arachnida, the body in the Opiliones has two tagmata, the anterior cephalothorax or prosoma, and the posterior 10-segmented abdomen or opisthosoma. The most easily discernible difference between harvestmen and spiders is that in harvestmen, the connection between the cephalothorax and abdomen is broad, so that the body appears to be a single oval structure. Other differences include the fact that Opiliones have no venom glands in their chelicerae, so pose no danger to humans. They also have no silk glands and therefore do not build webs. In some highly derived species, the first five abdominal segments are fused into a dorsal shield called the scutum, which in most such species is fused with the carapace. Some such Opiliones only have this shield in the males. In some species, the two posterior abdominal segments are reduced. Some of them are divi...
Many species are omnivorous, eating primarily small insects and all kinds of plant material and fungi. Some are scavengers, feeding upon dead organisms, bird dung, and other fecal material. Such a broad range is unusual in other arachnids, which are typically pure predators. Most hunting harvestmen ambush their prey, although active hunting is also found. Because their eyes cannot form images, they use their second pair of legs as antennae to explore their environment. Unlike most other arachnids, harvestmen do not have a sucking stomach or a filtering mechanism. Rather, they ingest small particles of their food, thus making them vulnerable to internal parasites such as gregarines. Although parthenogenetic species do occur, most harvestmen reproduce sexually. Mating involves direct copulation, rather than the deposition of a spermatophore. The males of some species offer a secretion (nuptial gift) from their chelicerae to the female before copulation. Sometimes, the male guards the...
Predators of harvestmen include a variety of animals, including some mammals, amphibians, and other arachnids like spiders and scorpions. Opiliones display a variety of primary and secondary defenses against predation, ranging from morphological traits such as body armor to behavioral responses to chemical secretions.Some of these defenses have been attributed and restricted to specific groups of harvestmen.
All troglobitic species (of all animal taxa) are considered to be at least threatened in Brazil. Four species of Opiliones are on the Brazilian national list of endangered species, all of them cave-dwelling: Giupponia chagasi, Iandumoema uai, Pachylospeleus strinatii and Spaeleoleptes spaeleus. Several Opiliones in Argentina appear to be vulnerable, if not endangered. These include Pachyloidellus fulvigranulatus, which is found only on top of Cerro Uritorco, the highest peak in the Sierras Chicas chain (provincia de Cordoba) and Pachyloides borellii is in rainforest patches in northwest Argentina which are in an area being dramatically destroyed by humans. The cave-living Picunchenops spelaeusis apparently endangered through human action. So far, no harvestman has been included in any kind of a Red List in Argentina, so they receive no protection. Maiorerus randoi has only been found in one cave in the Canary Islands. It is included in the Catálogo Nacional de especies amenazadas (N...
An urban legend claims that the harvestman is the most venomous animal in the world, but possesses fangs too short or a mouth too round and small to bite a human, rendering it harmless (the same myth applies to Pholcus phalangioides and the cranefly, which are both also called a "daddy longlegs"). This is untrue on several counts. None of the known species of harvestmen has venom glands; their cheliceraeare not hollowed fangs but grasping claws that are typically very small and not strong enough to break human skin.
Harvestmen are a scientifically neglected group. Description of new taxa has always been dependent on the activity of a few dedicated taxonomists. Carl Friedrich Roewer described about a third (2,260) of today's known species from the 1910s to the 1950s, and published the landmark systematic work Die Weberknechte der Erde (Harvestmen of the World) in 1923, with descriptions of all species known to that time. Other important taxonomists in this field include:Pierre Latreille (18th century)Carl Ludwig Koch, Maximilian Perty (1830s-1850s)L. Koch, Tord Tamerlan Teodor Thorell (1860s-1870s)Eugène Simon, William Sørensen (1880s-1890s)James C. Cokendolpher, Raymond Forster, Jürgen Gruber, Reginald Frederick Lawrence, Jochen Martens, Cândido Firmino de Mello-Leitão (20th century)Gonzalo Giribet, Adriano Brilhante Kury, Tone Novak (21st century). Since the 1990s, study of the biology and ecology of harvestmen has intensified, especially in South America.
Harvestmen are ancient arachnids. Fossils from the Devonian Rhynie chert, 410 million years ago, already show characteristics like tracheae and sexual organs, indicating that the group has lived on land since that time. Despite being similar in appearance to, and often confused with, spiders, they are probably closely related to the scorpions, pseudoscorpions, and solifuges; these four orders form the clade Dromopoda. The Opiliones have remained almost unchanged morphologically over a long period. Indeed, one species discovered in China, Mesobunus martensi, fossilized by fine-grained volcanic ash around 165 million years ago, is hardly discernible from modern-day harvestmen and has been placed in the extant family Sclerosomatidae.
The Swedish naturalist and arachnologist Carl Jakob Sundevall (1801–1875) honored the naturalist Martin Lister (1638–1712) by adopting Lister's term Opiliones for this order, known in Lister's days as "harvest spiders" or "shepherd spiders", from Latin opilio, "shepherd"; Lister characterized three species from England (although not formally describing them, being a pre-Linnaean work).In England, the Opiliones has been christened Harvestmen, not because they appear at that season, but from a superstitious belief that if one be killed there will be a bad harvest that year.
The interfamilial relationships within Opiliones are not yet fully resolved, although significant strides have been made in recent years to determine these relationships. The following list is a compilation of interfamilial relationships recovered from several recent phylogenetic studies, although the placement and even monophyly of several taxa are still in question. The family Stygophalangiidae (one species, Stygophalangium karamani) from underground waters in North Macedoniais sometimes misplaced in the Phalangioidea. It is not a harvestman.
Despite their long history, few harvestman fossils are known. This is mainly due to their delicate body structure and terrestrial habitat, making them unlikely to be found in sediments. As a consequence, most known fossils have been preserved within amber. The oldest known harvestman, from the 410-million-year-old Devonian Rhynie chert, displayed almost all the characteristics of modern species, placing the origin of harvestmen in the Silurian, or even earlier. A recent molecular study of Opiliones, however, dated the origin of the order at about 473 million years ago (Mya), during the Ordovician. No fossils of the Cyphophthalmi or Laniatores much older than 50 million years are known, despite the former presenting a basal clade, and the latter having probably diverged from the Dyspnoi more than 300 Mya. Naturally, most finds are from comparatively recent times. More than 20 fossil species are known from the Cenozoic, three from the Mesozoic, and at least seven from the Paleozoic.
Jun 07, 2015 · Therefore, we investigated the function of hth in the harvestman Phalangium opilio. We hypothesized that if patterning of the antenna and chelicera is homologous, then knockdown of Po-hth should result in a chelicera-to-leg homeotic transformation (as observed for insect hth knockdowns [ 13 , 16 , 19 , 24 , 26 ]).
- Prashant P. Sharma, Oscar A. Tarazona, Davys H. Lopez, Evelyn E. Schwager, Martin J. Cohn, Ward C. W...
Brown University, Providence, Rhode Island 02912 USA ABSTRACT. Harvestmen Phalangium opilio regularly feed upon the carcasses of bees and moths dis-carded by crab spiders Misumena vatia Clerck 1757 hunting on flowers. I report one observation of a harvestman unsuccessfully attempting to secure a bee still being fed on by a crab spider.
- Materials and Methods
Members of the order Opiliones (Arachnida) are omnivorous, but their diet consists primarily of small, soft-bodied organisms (Sankey and Savory 1974). As predators, primarily at night, harvestmen consume other harvestmen, gastropods, small earthworms, millipedes, spiders, mites, earwigs, flies, springtails, aphids, leafhoppers, and additional types of insects (Bristowe 1949, Sankey 1949, Sankey and Savory 1974, Nyffeler and Symondson 2001). The prevalence of opilionids in agroecosystems has been noted in previous studies. Predation by opilionids has been reported in agricultural and horticultural systems (Ashby and Pottinger 1974, Leathwick and Winterbourn 1984, Brust et al. 1986, Butcher et al. 1988, Drummond et al. 1990, Clark et al. 1994, Sivasubramaniam et al. 1997, Halaj and Cady 2000, Pfannenstiel and Yeargan 2002), orchards (Carroll 1982), woodlands (Adams 1984), and urban environments (Hanks and Denno 1993). Studies conducted in the midwestern United States have elucidated t...
Laboratory colonies of both H. zea and A. glycines were maintained at the University of Kentucky for each experiment. H. zea was maintained using methods similar to those of Ignoffo (1965). A colony of A. glycineswas kept on soybean in a greenhouse at 16:8 (L:D) and 24–30°C. The amount of prey provided always exceeded the predator's daily consumption in both experiments. For both experiments, P. opilio were collected at the University of Kentucky's North Farm near Lexington, KY. Field-collected individuals were either large nymphs, which were reared to maturity in the laboratory, or adults. In the laboratory, adult males and females were paired and housed in large petri dishes, 15 by 4 cm (diameter by height), with mesh-covered holes (9 cm diameter) in the tops. Males and females were distinguished by the presence (on males) or absence of a prominent apophysis on the distal segment of the chelicera. Pairs were provided with food and water and were stored in incubators at 24 ± 1°C (1...
Several factors affect the development and reproduction of predators, including the quality and complexity of diet. Some predators may incur low survival, long developmental periods, and lower fecundity when they feed on low-quality prey (Toft and Wise 1999). Toft (1995) found that the linyphiid spider Erigone atra (Blackwall) had increased reproductive success when fed a mixed diet compared with a monotypic diet, and he hypothesized that the effect of dietary mixing depends on the quality of the prey species being mixed. Atypena formosana (Oi), another linyphiid, also experienced higher fecundity when fed a mixed diet compared with a diet of only Collembola (Entomobryidae) (Sigsgaard et al. 2001). In general, these studies suggest that mixed diets are better than monotypic diets for reproduction, although the quality of the prey species involved can influence the effects of a mixed diet. Phalangium opilio incurred higher mortality, longer developmental periods, and smaller adult bo...
- Cora M. Allard, Kenneth V. Yeargan
1763 Behavioral roles of the sexually dimorphic structures in the male harvestman, Phalangium opilio (Opiliones, Phalangiidae) Rodrigo H. Willemart, Jean-Pierre Farine, Alfredo V. Peretti, and Pedro Gnaspini Abstract: In various animal species, male sexual dimorphic characters may be used during intrasexual contests as orna- ments to attract females, or to hold them before, during, or after ...
Phalangium opilio L. is a polyphagous predator frequently found in agricultural habitats. Although the potential importance of P. opilio's feeding on pests has been recognized, little is known ...