What kind of spider?

What kind of spider?

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I'd much appreciate help figuring out what kind of spider this is. I'm in Western Washington, in the northern suburbs of Seattle. Its outside, on the eaves of the house. Particularly wondering if a yellow sac spider.

Interesting! The size, shape and posture, as well as the visible patterning on the body, are all reminiscent of Dolomedes tenebrosus, the common terrestrial fishing spider here in the east. However, there are a couple of odd things here: 1. Dolomedes is a genus only found (as far as I know) in the eastern half of the US, 2. The abdominal color pattern is a bit off from what I would expect (dark flank marks at the front of the abdomen, especially), and 3. That looks like an egg sac the spider is sitting on top of, as if it was guarding, but fishing spiders (as far as I know) do not make egg sacs like that - they make ball-shaped egg sacs which they carry around with them using their fangs to hold them.

The thing is, nothing else rings a bell with me - the only other large wandering hunter that would be anything like that in the Pacific NW, that I know of, is the Giant Crab Spider Olios giganteus, which doesn't look much like that, although it does make a silken retreat/egg sac protection.

I confess that I am stumped, although I can confidently say that it is not a Yellow Sac Spider.

However, I can suggest two good options for identification: the Burke Museum:

and Bug Guide:

both of which can often do identifications from photos alone (although with spiders, this can sometimes be tricky). Good luck!

New protein found in strongest spider web material

Credit: CC0 Public Domain

A team of researchers affiliated with several institutions in the U.S. and Slovenia has found a previously unknown protein in the strongest known spider web material. In their paper published in the journal Communications Biology, the group describes their study of Darwin's bark spider silk and the glands that produce it.

Humans have been impressed by the silk made from spiders for thousands of years—so much so that a lot of effort has been put into harvesting it from spiders for use in making clothing—and in reproducing it in a lab to create new strong materials. In this new effort, the researchers focused their efforts on Darwin's bark spiders, their silk-producing glands and the silk that is produced.

Darwin's bark spiders are a type of orb spider, which means they make their spider webs in the shape of a spoked wheel. They make the largest known orb webs of any spider, which they spin above the surfaces of streams. Prior research has shown that the spider actually makes seven different kinds of silk for use in different parts of its web. One of those silk types, called dragline, is used to build the spokes that give the wheel its strength. Prior research has shown it to be the strongest spider silk in existence. In this new effort, the researchers took a closer look at the dragline silk and the gland that produces it.

The researchers found two familiar types of spindroins—types of repetitive proteins—called MaSp1 and MaSp2, which are found in many spider silks. But in the dragline from Darwin's bark spiders, they found another spindroin, which they named MaSp4a. Study of this protein revealed that contained high quanitities of an amino acid called proline, which prior research has shown is generally associated with elasticity. The protein also had less of some of the other components found in MaSp1 and MaSp2, which made it quite unique.

The researchers also found that the gland that produces the silk—the ampullae—is longer than in other spiders, perhaps providing another clue to the strength of the silk that is produced.

What are Spiders

Spiders are a type of arachnids. Around 50,000 spider species can be found all over the world (except in Antarctica). The body of spiders is divided into two segments: cephalothorax and abdomen. Spiders may have up to eight, simple eyes. The eight pairs of jointed appendages or legs are connected to the cephalothorax. Cephalothorax consists of mouth fangs, brain, stomach, and glands, which produce poisons. The multiple eyes of a jumping spider are shown in figure 1.

Figure 1: Multiple Eyes of a Jumping Spider

The tiny, leg-ish structures that surround the mouth fangs are called pedipalps. They hold the prey. Spiders do not have wings. The abdomen of the spiders consists of a type of glands called spinneret from which silk is released to the outside. Most spiders make their webs. Spiders secrete oils to stick their body to the web. The hairs on the legs of the spiders are sensitive to vibrations and smells. Each leg consists of six joints. Therefore, spiders have 48 knees. A spider web is shown in figure 2.

Figure 2: Spider Web

Spiders undergo incomplete metamorphosis. The three stages of the life cycle of a spider are egg, larva/nymph, and adult. Spiders feed only on liquid food. Therefore, they have a tinny gut. Most spiders are predators who inject venom into the prey to kill it. However, there are herbivorous spiders as well.

Biology of Spiders 3rd Edition

It is now exactly 30 years that Biology of Spiders was fi rst published, and I never expected nor planned to follow up with any further editions. When the science editor of Oxford University Press asked me last year whether I would prepare a thirdedition, I had at fi rst strong reservations because I knew vaguely how much work would be in stock for me: 12 years had passed since the second edition, and literally thousands of articles about spiders had been published during that time. I took up the challenge anyway and subsequently spent an entire year working exclusively on this new edition. Going through the enormous amount of spider literature was only possible through the internet, rapid information exchange by e-mail, and the support of kind colleagues who sent me with their latest spider publications. Including the major results of arachnological research of the past decade, it was thus possible to update all ten chapters. This is not to say that it is a complete revision&mdashof course, there will be omissions, deliberate and unconscious ones. My goal was always to provide a readable book on the biology of spiders, not an encyclopedia. The fact that this new edition nevertheless contains more than 500 new references gives some idea of how much of the recent literature has been incorporated.

Particular attention was paid to the illustrations. Since all the former drawings and photographs had to be scanned anew, this provided a good opportunity to improve and to correct any fl aws in the 200 illustrations of the last edition. Almost 100 new pictures have been added to the present edition, often originals that were taken specifi cally for this book. Many unique photographs were contributed by fellow arachnologists, to whom I am most grateful.

My thanks go to the following colleagues for their help and support: Friedrich Barth, Jon Coddington, Paula Cushing, Bill Eberhard, Bruno Erb, Cheryl Hayashi, David Hill, Martin Huber, Yael Lubin, Peter Michalik, Wolfgang Nentwig, Martin Nyffeler, Brent Opell, Bastian Rast, Robert Raven, Jerome Rovner, David Schürch, Karin Schütt, Paul Selden, Robert Suter, Rolf Thieleczek, George Uetz, Benno Wullschleger, and Samuel Zschokke. I also wish to express my gratitude to the following institutions: The Naturama Aargau for use of their computer and graphics facilities, the Neue Kantonsschule Aarau for letting me work on their electron microscopes, and the Smithsonian Institution in Washington, DC, for allowing access to the scientifi c literature. Finally, I´d like to thank my editor Phyllis Cohen and her colleagues Lisa Stallings, Karla Pace, and Jennifer Kowing at Oxford University Press and Anindita Sengupta at Glyph International for transforming my manuscript into an attractive book.
R. F. F.
January 2010

Do you like this book? Please share with your friends, let's read it !! :)

Professor of Biology and Vice Chair
Office 2318 Spieth Hall
Phone (951) 827-4322

E-mail: [email protected]

Ph.D., Yale University, 1996

**Effective January, 2017, Dr. Hayashi has moved to the American Museum of Natural History in New York. Click here.

Spider silks are among the most diverse and interesting of animal structural proteins. The large variety of silk types results from a multitude of uses, both within and between species. In addition to the huge diversity of spider taxa (they are one of the most species-rich of major animal groups), each individual produces as many as six or seven distinct varieties of silk from a battery of specialized glands. The different silks serve different purposes, ranging from web construction and prey capture to courtship and nest-building. The mechanical properties of silk -- elasticity, tensile properties, breaking strength, etc. -- are ultimately dependent on the sequence of amino acids that form silk proteins. Dr. Hayashi is interested in spider silks across many levels of biological integration, from the molecular genetics and evolution of the various silk genes to analyses of the protein sequences of different types of silk to biomechanical testing of the functional properties of the final product. Because of the unusually tight linkage between silk gene DNA sequences and functional ecology, these studies have easily understood connections to ecological, behavioral, and evolutionary questions.

What Are Some Adaptations That Spiders Have?

Spider adaptations include sticky webs, venom, quick movement and various anatomical adaptations. The specific adaptations that help spiders survive depend on the species. Some spiders have developed additional coloration adaptations, such as warning colors or camouflage, while others have developed behavioral adaptations.

Most spiders spin sticky webs which they use to capture insects. Their venom paralyzes the prey. Spider venom also works as a digestive enzyme, which dissolves the insides of the prey, allowing spiders to drink the nutrients. The venom can also work as a preservative. In this case, spiders can wrap the insect in their web for storage and later consumption.

Spider anatomy allows for locomotive adaptations. Because of their eight legs made up of seven segments each, spiders can move quickly and adeptly. Certain spiders, such as the common house spider, have special adaptations to their hind legs. They have six to 10 comb-like bristles that they use to fling their silk over their prey to wrap and preserve their victims.

Funnel web spiders, on the other hand, have adapted to the harsh desert conditions of Australia. Rather than rely on webs to trap prey, they aggressively attack other insects. Sturdy, powerful legs aid this adaptation, as do the small hairs that grow all over their legs and bodies.

Some spiders, such as sand spiders, have developed camouflage colors so that they blend into their surroundings. Others, such as the black widow, have bright warning coloration, which scares off other organisms.

Many species of the orb-web spider genus Cyclosa often adorn their webs with decorations of prey remains, egg sacs and/or plant detritus, termed`detritus decorations'. These detritus decorations have been hypothesised to camouflage the spider from predators or prey and thus reduce predation risk or increase foraging success. In the present study, we tested these two alternative hypotheses simultaneously using two types of detritus decorations(prey remain and egg sac) built by Cyclosa mulmeinensis (Thorell). By monitoring the possible responses of predators to spiders on their webs with and without decorations in the field, we tested whether web decorations would reduce the mortality of spiders. Wasp predators were observed to fly in the vicinity of webs with decorations slightly more often than in the vicinity of webs without decorations but there were very few attacks on spiders by wasps. By comparing the insect interception rates of webs with and without decorations in the field, we tested whether web decorations would increase the foraging success. Webs decorated with prey remains or egg sacs intercepted more insects than those without in the field. By calculating colour contrasts of both prey-remain and egg-sac decorations against spiders viewed by bird(blue tits) and hymenopteran (e.g. wasps) predators as well as hymenopteran(bees) prey, we showed that C. mulmeinensis spiders on webs with egg-sac decorations were invisible to both hymenopteran prey and predators and bird predators over short and long distances. While spiders on webs with prey-remain decorations were invisible to both hymenopterans and birds over short distances, spiders on webs with prey-remain decorations were visible to both predators and prey over long distances. Our results thus suggest that decorating webs with prey remains and egg sacs in C. mulmeinensis may primarily function as camouflage to conceal the spider from insects rather than as prey attractants, possibly contributing to the interception of more insect prey. However, the detritus decorations exhibit varying success as camouflage against predators, depending on whether predators are jumping spiders, wasps or birds, as well as on the decoration type.

A conflict in signalling can exist because of different interests of the signaller and the receiver (Guilford and Dawkins, 1991 Schaefer et al., 2004). This gives rise to deceptive behaviour where the behaviour of the signaller induces the receiver to register a situation that does not occur in reality but actually benefits the signaller whereas the receiver incurs a cost (Semple and McComb,1996). Cryptic colouration and behaviour is a form of behavioural deception and has been suggested to allow diurnally active spiders to escape the notice of predators(Cloudsley-Thompson, 1995). Crypsis can be achieved via physical appearance (e.g. colour patterns) but also via behavioural traits or both, which prevent the prey from being detected (Stevens and Merilaita, 2009).

Orb-weaving spiders are documented to incorporate a variety of materials such as silk tufts, silk ribbons, prey remains, egg sacs and plant detritus into webs (called `web decorations') and a suite of functional hypotheses have been proposed for these web decorations (reviewed by Herberstein et al., 2000 Starks, 2002 Craig, 2003 Bruce, 2006). Web decorations are hypothesised to function as visual signals used for predator avoidance by making the spider look bigger (Schoener and Spiller, 1992), for predator defence(Blackledge and Wenzel, 1999 Blackledge and Wenzel, 2001 Eberhard, 2003 Eberhard, 2006 Jaffé et al., 2006),for web damage avoidance by advertising the presence of a web(Horton, 1980 Eisner and Nowicki, 1983 Kerr, 1993 Blackledge, 1998 Jaffé et al., 2006) or for prey attraction by reflecting UV light (e.g. Craig and Bernard, 1990 Tso, 1996 Tso, 1998 Herberstein, 2000 Bruce et al., 2001 Bruce et al., 2004 Bruce et al., 2005 Li et al., 2004 Li, 2005). Evidence in supporting these hypotheses is contradictory, although mostly supportive. Nevertheless, the majority of the related studies have been concentrated on silk decorations built mostly by a single genus, Argiope (Araneidae). Other types of decorations spun by other orb-weaving spiders have received little attention.

Spiders of the genus Cyclosa (Araneae: Araneidae) decorate their webs with not only silk but also prey remains, egg sacs and plant detritus so called `detritus decorations', and usually have cryptic body colouration similar to that of the detritus decorations that they build and rest amidst(Comstock 1913 Marson, 1947 Rovner, 1976 Neet, 1990). These detritus decorations are generally thought to conceal spiders from predators(Eberhard, 1973). However, few species and forms of detritus decorations have been studied in the genus Cyclosa. Using field manipulative experiments and modelling visual systems of potential prey and predators, Chou and colleagues have tested the function of prey-remain decorations built by Cyclosa confusa from Taiwan (Chou et al., 2005). They found that prey-remain decorations do not attract insects but rather mislead predators to attack the decorations instead of the spider and/or allow time for the spider to escape the advances of predators. Artificial webs with detritus decorations of two species of Cyclosa (C. morettesand C. fililineata) are also found to be unattractive to insects, and Gonzaga and Vasconcellos-Neto argued against the prey-attraction hypothesis and suggested that decorating webs with detritus may reduce predation(Gonzaga and Vasconcellos-Neto,2005). Cyclosa mulmeinensis (Thorell) spans from Africa to East Asia and was previously recorded in rainforests in various parts of mainland Singapore (Koh, 1991 Tanikawa, 1992 Song at el., 2002 Platnick, 2008). C. mulmeinensis has a pale brown abdomen mottled with dark brown spots, and often adds prey remains in a continuous chain vertically radiating from the hub upwards to the web frame (Fig. 1A). On occasion, these prey remains also extend below the hub and downwards. C. mulmeinensis usually rests at the hub, in line with its web decorations (Fig. 1). Although the spiders rebuild their webs daily, most do not dispose of their collection of prey remains, keeping the frame on which the prey carcasses are attached. Often the egg sacs covered in prey remains vertically radiate from the hub upwards to the web frame in the webs of female spiders(Fig. 1B). Positioning itself at the hub, the spider appears to be part of the line of cryptic prey remains and egg sacs.

Spiders and their eggs are preyed on by a list of predators such as earwigs, wasps, lizards, birds and other spiders(Foelix, 1996 Rayor, 1996). Together with its prey remain-based web decorations, the abdomen pattern of C. mulmeinensis resembles detritus. As detritus is less noticeable and unpalatable, the web-decorating behaviour of C. mulmeinensis may be to camouflage itself from potential predators(Marson, 1947 Eberhard, 1973 Lubin, 1975 Baba, 2003 Chou et al., 2005). However,web decorations composed of prey remains may have another function – to attract prey by chemical cues released by the yeasts growing on the prey-remain decorations (Tietjen et al.,1987). The present study investigates if prey-remain and egg-sac decorations camouflage C. mulmeinensis from potential predators or improve foraging success. Direct tests of the predator-defence hypothesis and the prey-attraction hypothesis were performed by recording the responses of predators and prey to spiders on decorated webs in the field. To evaluate individual camouflage efficiency, chromatic and achromatic contrasts of each pair of spiders and their respective decoration were calculated. Next, the spectral sensitivities of an insectivorous avian predator and a trichromatic hymenopteran were used to evaluate the spiders' camouflage efficiency with respect to the visual systems of possible predators and prey.

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What Does Marijuana Do to Spiders?

Jason mentioned the other day that he and his wife were watching the new series Orange is the New Black, wherein one of the characters talks about how deer were eating her marijuana plants. The factoid checked out. Deer really are a problem for pot growers because fresh growth on the plants makes an excellent snack.

According to forest rangers who were led to a hilltop grow site by under-the-influence animals in Italy, deer who’ve consumed marijuana plants are “unusually frisky” and “abnormally high-spirited.” This got us wondering what kind of effect marijuana had on other animals.

Cannabinoid receptors have been found in non-human mammals, birds, reptiles, fish and even some invertebrates, so there are plenty of animals that react to marijuana. Most of those reactions aren’t that surprising, or all that interesting, though. Dogs and cats act kind of funny and groggy after eating weed (please don’t feed them your stash, no matter how YouTube famous you want to be, though—the stuff can be toxic to them, especially dogs), and monkeys exposed to THC keep wanting more.

Spiders, though, are infinitely interesting when they get stoned because the effects of the drug are clear in the odd-looking webs they build afterwards.

Getting spiders high for science started in 1948, when German zoologist H.M. Peters got fed up with trying to study web-building behavior in spiders who wouldn't do him the courtesy of working on his schedule. His garden spiders tended to build their webs between two and five a.m., and he asked his pharmacologist friend P.N. Witt if there might be some chemical stimulant that would coax the spiders into building their webs at a more reasonable time.

Witt tried giving the spiders some amphetamine and, while they kept building at their usual hour (to Peters' dismay), the two scientists did notice that those webs were more haphazard than normal. Over the next few decades, Witt continued to dose spiders with a smorgasbord of psychoactive substances, including marijuana, LSD, caffeine and mescaline, to see how they reacted. Since spiders can’t use tiny bongs or drink from little mugs, Witt and his team either dissolved the drugs in sugar water or injected them into flies and then fed the spiders with them.

The drugs affected the size and shape of the spiders’ webs, the number of radii and spirals, the regularity of thread placement and other characteristics. By comparing photographs and measurements of normal and “drug webs,” Witt and other researchers could see how the different substances affected different aspects of the web and, by extension, the spiders’ motor skills and behavior.

The line of study didn’t have many practical applications at the time and was eventually discontinued. In 1995, though, NASA repeated some of Witt’s experiments and analyzed the webs with modern statistical tools and image processors. This allowed them to quantify the differences between webs, and they suggested that comparisons like this could be used to test the toxicity of different chemicals on spiders instead of “higher” animals like mice, saving time and money.

What a web they weave

This is your web on drugs.

Specifically, this a web on marijuana. It was made by one of the NASA spiders, which appears to have given up on it halfway through. NASA says the spiders that were given marijuana were easily sidetracked while building and left their webs unfinished.

The spiders on benzedrine, a stimulant also known as “bennies,” weaved their webs energetically, even frantically, but without planning or attention to detail. Their webs were characterized by large gaps.

Caffeinated spiders made smaller, but wider webs, characterized by threads meeting at wide angles, disorganized cells and a lack of the normal “hub and spoke” pattern.

Spiders given the sedative chloral hydrate gave up on their webs even faster than the ones who’d had a little pot.

Finally, spiders given low doses of LSD actually maintained more geometric regularity than they did when they were stone sober.

7 Future perspectives and challenges

Synthetic biology has enormous potential to offer sustainable and green solutions for the production of a number of commodities, including biomaterials. The study of spider silks can immensely benefit from the progress of synthetic biology, and several of the recent advances in recombinant spider silk production – ranging from the identification of evolutionary design patterns correlating with mechanical properties to the engineering of silkworms for the production of mechanically enhanced chimeric silks – have only been possible due to the power of this cross-disciplinary approach.

A big obstacle in the high-throughput screening of spider silk variants is the necessity to characterise the mechanical properties of these new variants to determine their efficiency. The libraries of variants can be generated relatively rapidly by using automation and liquid handling robots, but purification and processing of the expressed spidroin variants in a high-throughput mode is still a big challenge. Furthermore, substantial amounts of protein are needed to perform the mechanical characterisation, which further acts as an impediment in this process. It has been suggested that protocols to measure alternate factors, which directly correlate with the desired mechanical property, in a high-throughput setting, have to be established [ 93 ]. This approach could help narrow down the pool of variants (hundreds or even thousands), so that only a selected few covering the spectrum of desired properties can be taken to the next stage of large-scale material tests and subsequent learning of design rules. Molecular modelling and simulation constitute another approach that can be used to further streamline the synthetic biology process. Rim et al. proposed an iterative protocol in which multiscale modelling is used to predict silk fibre properties based on the protein composition [ 94 ]. Model predictions are validated by carrying out DNA synthesis, protein expression, and subsequent mechanical testing. The data gathered is used to improve the predictive rules and thus feeds back into the iterative process.

Another challenge facing the successful production of artificial spider silk is the development of techniques for efficient spinning of spider silk, which can rival natural spider silk in its mechanical properties. Although a lot of research has been dedicated to understanding the events in the silk glands and the spinneret during spinning, translating them in vitro remains a challenge. Most importantly, obtaining feedstock dopes in high concentrations of up to 30–50% (w/w) remains difficult, and mimicking the apparatus of a spider's spinneret is also challenging [ 17 ]. Several techniques that have been developed include electrospinning [ 95, 96 ], spidroin self-assembly at air-water interfaces [ 97, 98 ], and the use of microfluidic devices [ 99 ]. It is to be noted here that none of these techniques have managed to match the mechanical properties of naturally produced spider silk. Koeppel and Holland, in their recent review, have discussed all available techniques in detail and also highlighted the challenges facing this important aspect of artificial spider silk production [ 66 ].

Overcoming all the challenges described above is important, but for the large-scale commercial production of spider silk to be viable, it needs to be cost efficient. Currently, several companies are involved in the production of spider silk using different methods. Kraig Biocraft Laboratories, using their genetically modified silkworms [ 80 ], have successfully managed to produce a kilogram of spider silk for ∼300 USD. This is by far the most economical spider silk production reported so far [ 82 ], but further improvements are needed to bring down the costs for the economical production of artificial spider silk on a large scale. Both, synthetic biology and spider silk research are currently undergoing a phase of rapid progress – combining their forces will result in the rapid realisation of the full potential of spider silk as a key ingredient to a broad range of valuable biomimetic materials.

Watch the video: Αράχνες Spiders (May 2022).


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