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RE: Spiders - Tshokwane - 03-11-2017
Credits to The Silk Road. Photo credits to Faiz Bustamente.
Portia cf. labiata.
Portia spiders have displayed some of the most capable and intelligent hunting strategies ever witnessed in the animal kingdom. Here are several of those different and amazing strategies that have been studied at length: Cryptic mimicry by looking like detritus or leaf litter and remaining motionless if it notices its prey surveying its surroundings. Moves very slowly to remain camouflage and draws its pedipalps in so they are noticed.
Shaking another spider's web in perfect timing to imitate an insect that has been caught in it and thus draw the prey out of its hiding place. This can be done in a manner of different ways, and is called nest probing. Research has shown that the portia spider will engage in species-specific web shaking that elicits a response from its prey.
When approaching a spider on its own web, the portia spider will only move when a gust of wind blows by in order to keep the other spider from recognizing its advance.
Portia spiders approach spitting spiders from behind in order to stay out of range of the dangerous venom they are capable of spraying their prey with venom.
Portia spiders contain a venomous bite that is just sufficient to kill other spiders and insects.
Finally,Portia spiders display amazing patience and have been observed studying their prey for 3 whole days before moving in to attack. Portia spiders have exhibited detour behavior, meaning they see and recognize prey and will determine the best and safest route to approach the prey. Sometimes this involves an elaborate, long detour. This spider is without doubt an Einstein of the Arachnid world and I salute you Portia.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 03-14-2017
Credits to Niela's Peculiar Photography.
Hackled-mesh web weavers
(Family Phyxelididae)
Some people wouldn't bother to take a second look at these spiders as they are very common in most parts of South Africa, but I think they have a rather rare beauty to them.
I usually find them in dark and damp places under stones & bark, holes in trees and even in crevices where they will make a cribellated funnel-like signal web as you can see in photo number 3. The easiest way to identify them is by their web. They have 8 eyes arranged in two rows (4:4), legs are long and slender, they are drab brown or grey and their abdomens are oval, usually with a dense layer of setae (hair) and sometimes have a defined pattern. Body size ranges from 3-16mm.
Males are slightly smaller than females, their legs more slender and adult males will have enlarged pedipalps.
These are clever nocturnal hunters, they sit and wait patiently for prey to walk by and trip one of the signal lines, they will then rush over to overpower it, inject venom into the prey and then enjoy their meal.
They are harmless to humans and pets of course.
*This image is copyright of its original author
*This image is copyright of its original author
*This image is copyright of its original author
RE: Spiders - Tshokwane - 03-19-2017
Credits to The Silk Road.
Male and female Ligurra latidens, commonly known as the Mangrove Jumper. Distribution is Malaysia to Indonesia. The male jaws are quite elongated and have a projecting spur, which is used to lock jaws with the female during mating.
These remarkable photos were taken by Husni Che Ngah.
Male.
*This image is copyright of its original author
Female.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 03-26-2017
Biologists say wolf spiders have a wider range of personality than once believed: By Michael Miller.
Charming might not be the best way to describe a spider, but researchers at the University of Cincinnati are finding a wide spectrum of personality in a creature whose behavior was thought to be inflexible and hardwired in its genes.
UC biology professor George Uetz has dedicated his career to the study of spiders, wolf spiders in particular. Spiders are simpler in neurophysiology than mice or other vertebrates, so their behavior should be determined more by DNA than any quirkiness among individuals.
But Uetz said spiders have more charisma than he ever imagined.
"There's a lot of variability in the individual," he said. "Some of that that arises from experience, just as in more complex animals."
More than 200 species of wolf spiders live in the United States. As their name implies, they stalk their prey on the forest floor and in dry creek beds. They are lone wolves, living and hunting on their own except for mating encounters, which are the subject of two studies this year by UC graduate students.
One UC student, Emily Pickett, examined two closely related species that look alike and share habitat. While the two spiders can interbreed, it's rare in the wild. Pickett found that their unique courtship behavior helps maintain their genetic isolation. One spider, Schizocosa ocreata, could woo females over a greater distance than the other, Schizocosa rovneri, by employing a combination of vibrations and visual signals unique to the species.
"We hypothesized that the two species diverged relatively recently. This gives us good insights into the modification of species—how one species develops into another," Pickett said.
Since spiders don't hear the way we do, they rely on vibrations, chemical cues and visual signals to communicate.
A second study by graduate student Madeline Lallo examined yet a third wolf spider, Gladicosa bellamyi, and found that males bounced their bodies and waved their pigmented forelegs like flags to get the attention of females.
The students and their co-author, professor Uetz, presented their findings in March at the Midwest Ecology and Evolution Conference at the University of Illinois. The conference accepted 95 papers from universities across the Midwest.
Students Pickett and Lallo are building on an investigation of spiders that professor Uetz began more than 40 years ago. Uetz has co-authored 120 peer-reviewed papers, chronicling how spiders communicate, select the best mate and learn from their mistakes. In 1976, he compiled a comprehensive list of native spiders found in Delaware.
Scientists often choose fruit flies, nematodes or mice for research subjects because so much is already known about them, including whole genomes. Wolf spiders, too, are fast becoming a template for research because of work at UC and other universities.
"In the long view, we're building a new model organism for study," he said. "We know a great deal about [the spider's] behavior and are learning more about their physiology and immunology."
Uetz said spider behavior relies on multiple sensory systems completely different from our own and those of other vertebrate animals. Their visual, vibratory and chemical senses provide insights about the evolution of nervous systems and brain function.
UC is helping to turn wolf spiders like this one (Schizocosa ocreata) into a model organism to study disease or environmental issues to benefit people. Credit: Joseph Fuqua II/UC Creative Services
*This image is copyright of its original author
Each new study begins at the Cincinnati Nature Center where researchers collect wild spiders in the forest. Finding wolf spiders with LED flashlights is surprisingly easy at night. (Arachnophobes might say it's horrifyingly easy.) Their eyes glitter in the lamplight like green gemstones.
"They blend in really well with the leaf litter. But at night you can see all those eyes shining back. You have no idea how many spiders are actually in your backyard until you put a headlamp on and look," Lallo said.
Researchers scoop up the spiders and sort them by species and sex.
The biology lab is home to as many as 1,800 spiders at any time, which again could make some people anxious.
"For some people it's a hard, 'Nope!'" Lallo said. "I understand why some people can be afraid of them. But they're just too small to bite us."
Despite their ferocious name, wolf spiders are harmless to people. Researchers casually handle them by scooting them into vials or prodding them around their plastic containers.
Researchers feed pinhead crickets to their experimental subjects twice a week. The spiders drink from a sponge that soaks up water from a recessed reservoir.
Lallo studied the courtship behavior of Gladicosa bellamyi by leaving a female overnight in a clear plastic bowl called an arena. The bottom is covered in a paper disk that helps researchers detect minute vibrations whenever the spider walks, scratches or engages in a courtship dance. Left to her own devices, the female spins a trail of pheromone-laced silk that is irresistible to male spiders.
Males can read chemical cues in silk to determine if a female is receptive, has already mated or even if it has cannibalized other males in the past, Uetz said.
"They will either avoid those females completely—hide and try to be invisible—or else court furiously to overwhelm her senses," he said.
The next day they place the arena atop a laser doppler vibrometer in the lab's soundproof recording studio. The laser beam converts vibrations in the filter paper into a digital rendering that researchers can compare side by side with other examples.
They drop a male in with the female and use a video camera and the vibrometer to record what happens.
In about 10 percent of Schizocosa ocreata mating encounters, the female immediately eats the male. The rate of cannibalism can be as high as half of the encounters in other species, so wolf spiders walk a thin line between courtship and consumption.
For a demonstration, they paired two spiders and waited. Up close, the ocreata is camouflaged with brindled brown and black fur. But the male's forelegs are covered in thick black bristles like a dancer's leg warmers.
With its antic mating dance, ocreata has a nickname in the lab: "the twerking spider."
The male raises his fuzzy appendages over his head while bouncing his body and fangs on the ground to create vibrations. Generally, spiders that make the strongest vibrations have the best breeding success, Uetz said.
The researchers watched as the male began to wave his front legs and strike the filter paper. "Here he goes," Uetz said. "Here comes the female. Now look at her. She's interested."
The female cautiously approached the male and did a curtsy—a spider invitation to mate. The male frantically bounced and waved.
"Yeah, she's excited. It's going to happen—unless the male gets a little skittish," Uetz said. Despite her apparent willingness, the male ran away to the edge of the arena where he resumed his dance, this time a little less enthusiastically. The female approached again and did another pivot and curtsy but the male again backed away.
"They were close but then she reared up slightly and scared him. She's armed and dangerous," Uetz said. "She's not being aggressive but he is clearly smaller than she is. He doesn't have a lot of experience."
After another minute of posing, the female suddenly chased the male in two frantic laps around the arena. Lallo rescued him before the encounter could turn gruesome.
The university's research has found that each species of wolf spider engages in a unique courtship dance, often employing multiple forms of communication.
"It's given us insights into the fact that this behavior is plastic. It's learned," Uetz said.
In other experiments, Uetz uses virtual reality to study spider communication. Spiders are placed in the arena in front of an iPod playing a recorded video of a spider of the opposite sex.
Researchers play recorded sound through the filter paper that mimics the vibrations observed from the dancing spider on the screen. Incredibly, the ruse works and researchers can elicit a mating response from the live spider.
Wolf spiders are selective about mating only within their species. But researchers can use digital animation to build their own chimeras or virtual hybrids to determine precisely what about the opposite sex stimulates a mating response. Phillip Taylor, a former postdoctoral researcher of Uetz's who is now an associate professor at Macquarie University in Australia, has taken the research a step further by using magnets to affix a spider to a rolling track ball in front of a three-dimensional screen to build a virtual world in which the spider can run around and interact with digital spiders.
Now UC's Uetz is turning his attention to the variability of behaviors within species—the advantages and disadvantages of being a bold or timid spider. If a male is too bold, he could get eaten by a female or passing bird. If he is too timid, he could survive but miss any chance to pass on his genes.
"This strong selection pressure to get the message across leads to the evolution of complex, multi-sensory behaviors," Uetz said. "He might contribute to future generations. Or he might be lunch."
Provided by: University of Cincinnati.
RE: Spiders - Tshokwane - 03-31-2017
Credits to Nick Monaghan.
Predator and prey. Predator is prey.
In the invertebrate world, no one is safe and you can never get complacent. Robber Flies (family Asilidae) are fearless hunters that will attack almost any insect. I have seen them kill bees, wasps and spiders, but this Robber Fly has met its match at the hands, or should I say fangs, of an Opisthoncus species jumping spider (family Salticidae). Who knows, maybe the spider will become the meal tomorrow.
Kinglake National Park, Victoria, Australia.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 04-01-2017
Credits to Melina Albornoz.
26 de febrero 2017, Diamante, Entre Ríos(Argentina).
The spider seems to be Steatoda sp, the scorpion (Alacrán as we say it here) Tityus sp. (dangerous).
*This image is copyright of its original author
*This image is copyright of its original author
RE: Spiders - Tshokwane - 04-09-2017
Credits to Kurt Orion G.
Giant armored trapdoor spider (Liphistius malayanus), highland of Pahang, Peninsular Malaysia.
*This image is copyright of its original author
I love these spiders, they look amazing.
RE: Spiders - Tshokwane - 07-07-2017
Credits to The Silk Road.
A stunning portrait of Thomisus onustus, photographed in the Kaiserstuhl by Achim Kluck.
In the UK this species occurs in dry or moderately wet, mainly mature, heathland, usually on flowers of Erica tetralix or E. cinerea, where it sits to ambush prey, mostly bees and large flies. Adult females can adjust their background colour to some extent in order to match that of the flower upon which they sit (Oxford & Gillespie 1998). Both sexes are adult in May and June, and females deposit their egg-sac in July spun up in flower heads of Erica.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 07-15-2017
Credits to The Silk Road.
Aphantochilus rogersi is a species of ant-mimicking crab spiders from South America. It is found from Panama to Paraguay.
It mimics ants of the genus Cephalotes, which are their preferred prey. It has the unusual behaviour of carrying the dead husks of ants aloft like a protective umbrella. Does this camouflage its identity and allow it to approach and overpower other ants, or maybe a form of defence to protect itself from its enemies? Whatever the reason, this is a unique little arachnid in my eyes.
Photo credit : Thiago G. Carvalho.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 07-18-2017
Credits to Lifeunseen - Nick Monaghan.
David and Goliath in miniature.
Bomis larvata is a tiny spider from the family Thomisidae, aka Crab and Flower Spiders, but even though it is only a few millimeters long, it is a fearless ant hunter. After ambushing its prey, the spider delivers a bite behind the ant's head, making any resistance sort-lived and futile.
Dandenong Ranges National Park, Victoria, Australia.
*This image is copyright of its original author
RE: Spiders - Ngala - 07-18-2017
Nephila senegalensis (Walckenaer, 1842)
From Sabi Sabi Private Game Reserve:
"A stunning Golden Orb Spider shows off its vivid colours at the start of one of our morning game drives."
*This image is copyright of its original author
RE: Spiders - Tshokwane - 08-12-2017
The truth about spider bites: “Aggressive” spiders and the threat to public health: This post was written with Chris Buddle, and originally appeared on his blog Expiscor at Scilogs.com.
Misinformation about spider bites is everywhere.
Spiders are polarizing: people tend to be fascinated or fearful, and for some, Arachnophobia can be quite serious. However, spiders are often feared unnecessarily. They are quickly blamed for almost ALL unexplained bites or lesions!
It doesn’t help that there is an incredible amount of misinformation and fear-mongering related to spiders in the popular media and all over the internet. What’s worse, misinformation about spiders also appears in the medical literature. For example, the journal Emergency Medicine recently published an article on bites and stings that made the following claims:
“The [hobo spider] is considered aggressive and tends to bite even with only mild provocation. The clinical presentation, inclusive of systemic reactions, is similar to that of the brown recluse spider.”
This got us all riled up, and we decided to set the facts straight:
1. The hobo spider is not aggressive.
Exhibit A
*This image is copyright of its original author
: the allegedly aggressive hobo spider. This female hobo was minding her own business on her webuntil being rudely removed to a human hand and made to pose for photographs.
As for its supposed tendency to bite when provoked, Samantha Vibert, an arachnologist at Simon Fraser University says,
“During my PhD, I’ve studied the ecology and courtship behaviour of the hobo spider, Eratigena agrestis. This work entailed surveying dense populations of the hobo spider in the field and conducting experiments in the lab. Over the course of several years, I’ve handled hundreds of hobo spiders. I am always puzzled when I hear the hobo spider described as an “aggressive” species. Their one and only strategy when disturbed is to run away. The only mildly disturbing thing about them is the speed with which they bolt! When they feel threatened, they’ll abandon their web and make a dash for the nearest dark corner. I can only assume that their bad reputation stems from 1) a misunderstanding of their scientific name (agrestis means “of the field”, and not “aggressive”) and 2) their appearance. For people who dislike spiders, their relatively large size and long legs are not endearing. In fact, this spider is very meek and gentle but sadly misunderstood!”
2. The evidence that hobo spiders cause dermonecrotic lesions is poor and largely circumstantial.
Hobo spiders are European, but they were introduced to North America in the early 20th century and have since become established in the northwestern US and British Columbia, Canada. Hobo spiders live peacefully alongside humans in Europe, where nobody seems to be all that concerned about them. A 2001 study found no support for the hypothesis that the venom of North American hobo spiders differed from that of their European counterparts in its ability to cause necrosis. Most of the evidence tying hobo spiders to dermonecrotic lesions in medical case studies is weak and circumstantial. For example, the mere presence of this species in the house or even the neighbourhood where the supposed bite victim lived has been used to implicate hobo spiders. There only seems to be one case reported in the medical literature with reasonably incriminating evidence – the dead spider was found crushed under a pant cuff. But even in this case, the person had a pre-existing medical condition and did not seek medical attention for more than 2 months after the bite, casting doubt on whether the spider’s venom was actually responsible for necrosis.
*This image is copyright of its original author
3. Spider bites are extremely rare, and often misdiagnosed.
It is disappointing to see these myths about spiders propagated among some doctors and the public, but more importantly, it is dangerous. Here is a list of some of the actual conditions that have been misdiagnosed as resulting from spider bites:
infections (bacterial, viral, and fungal)
cancers (basal cell carcinoma and lymphoma)
poison oak and ivy
burns
Lyme disease (resulting from tick bites)
vascular disorders
pyoderma gangrenosum
Arachnologists Robb Bennett and Rick Vetter advise doctors that,
“The criterion standard for spider-bite diagnosis should be a spider caught in the act of biting or otherwise reliably associated with a lesion (and properly identified by a qualified arachnologist). Unless this standard is met, a working diagnosis of a spider bite should not be considered. Any of the above conditions are more likely.”
In spite of there being no brown recluses in Canada, it is common to hear about people who have been diagnosed with brown recluse bites here. Most of these folks never saw a spider or felt a bite, but had their mysterious lesion diagnosed as a spider bite by their doctor, who they trust as an expert. This comic nicely sums up why the vast majority of the time, it is safe to assume that a spider did not bite you.
Even where there are brown recluse spiders, they hardly ever bite people. There was a family home in Kansas that had 2,055 brown recluse spiders collected from it over a 6-month period, and no one living in the house got bitten. Still not convinced? In Florida, medical professionals diagnosed 124 brown recluse bites over 6 years. That’s 124 people who accidentally got near enough to the alleged spiders to be bitten, while going about their everyday business (only one of them ever produced an actual brown recluse for identification). Arachnologists – we’re talking people who actively go around seeking outspiders in likely spots – found only 5 brown recluses in Florida over the same 6-year period and a total of only 70 brown recluse spiders over 100 years. The numbers simply do not add up.
Did we mention that spiders hardly ever bite people?
Sometimes spiders do bite people, and a few species are legitimately considered medically significant. In North America, black widows as well as brown recluse bites are serious and certainly may require medical attention. However, black widows in particular have an undeserved bad reputation. They are not aggressive, rarely bite, and even when they do, they often don’t inject any venom. Most news articles about black widows refer to them at least once as deadly – often in the headline. According to the American Association of Poison Control Centers, 2,246 black widow bites occurred in all of the United Stated in 2012 (that doesn’t mean they were verified as actual black widow bites, just that they got reported, so this is almost certainly an overestimate). Only 21 of these reported bites resulted in major, but non-lifethreatening, symptoms, and no one died. Compare those zero deaths with the 36,166 traffic fatalities in the US in 2012. Cars are not regularly described as deadly but perhaps they should be. It would be more reasonable to fear automobiles than black widows. Arachnophobia is of course a legitimate condition, but there really are a lot of worse things to worry about.
*This image is copyright of its original author
4. There are serious consequences of spider bite misinformation and misdiagnosis
Assuming every unknown lesion is a spider bite can prevent accurate diagnosis, and delay proper treatment. Inappropriate treatment based on the misdiagnosis may be ineffective or worse, harmful. Overzealous diagnoses of spider bites can also lead to arachnophobia and reckless, unwarranted attempts to rid homes of spiders. Unnecessary exposure to pesticides is probably much riskier than sharing your home with spiders.
In sum, we hope this post is seen as a “Public Service Announcement” (or better yet, a “Public Spider Announcement”) and that we can help dispel some myths about spiders. We should be celebrating their incredible biology and natural history, and we should look to spiders as our allies in controlling pest insects, or taking down mosquitoes.
We should look at spiders in awe, rather than in fear.
RE: Spiders - Tshokwane - 09-17-2017
Credits to The Silk Road.
A remarkable photo by Thiensak Mekkapan-opas .
This Olios jaenicke is on the hunt for a lady. The swollen palpal bulbs can clearly be seen, showing this guy is ready for business. The hook like structures are the tegular apophysis which are a characteristic feature of this species. This species was first described from Laos, Champasak by Peter Jaeger in 2012.
*This image is copyright of its original author
RE: Spiders - Ngala - 09-22-2017
Photo and information credits: Chris Ang
"Caerostris sp." Danum Valley Conservation Area, Sabah, Malaysia.
*This image is copyright of its original author
RE: Spiders - Tshokwane - 10-15-2017
Credits to Husni Che Ngah.
Malayan Black Trapdoor Spider
Liphistiidae - Liphistius malayanus.
*This image is copyright of its original author