Arachnews: May 2019
Published in
10 min readJun 7, 2019
Dispatches & Social Media
- Roses are red,
Australia has spiders,
This Eriophora
Caught a feathertail glider.
- Adam Fletcher of Project Maratus shares a wonderful picture of a peacock jumping spider’s tiny discarded “helmet”.
- Tone Killick, who previously photographed a mother hacklemesh weaver being devoured by her own young, is now documenting another well-known but rarely seen process: a goldenrod crab spider, Misumena vatia, changing colours.
- Adrian Tchaikovsky’s Arthur C. Clarke Award-winning 2015 novel Children of Time, featuring inadvertently uplifted Portia spiders, was an arachnophile must-read. The sequel, Children of Ruin, was released a few weeks ago. The spiders are back. And now there’s also octopuses.
Education & Outreach
For articles that are more educational than news-related, and aimed at the general public.
- This American Life’s Lilly Sullivan talks to Malcolm Rosenthal, who stood up for invertebrates when he highlighted an anti-arthropod bias in animal behaviour papers. (Transcript.)
- This video by Geoff Hyde shows how jumping spiders’ main pair of eyes work like miniature telescopes. You can see the eye tubes moving around inside a spider’s head!
- Citizen science project eTick.ca lets people upload pictures of ticks and get identifications and more information from local experts. At The Conversation, Jade Savage talks about the project’s origin and new developments.
- The latest Deep Look video is all about Demodex — the microscopic mites that live on your face. Check out the accompanying article as well.
- Art and science: two great tastes that taste great together. Brett Jeffrey Taylor describes how he made dozens of 3D spider models for teaching tools and even decoys in experiments.
- At Biocoenosis, Jordan Cuff has written a great, easy to understand profile of money spiders (family Linyphiidae), one of the most common spider families in the UK.
- For Skype a Scientist, spider researchers Shakira Quiñones-Lebrón and Dallas Haselhuhn gave tours of their labs live on YouTube. They each study very different kinds of spiders: Quiñones-Lebrón’s lab houses giant orbweavers, while Haselhuhn’s is filled with tarantulas and scorpions. You can re-watch the session here:
Events & News
- Trailblazing scientist Barbara York Main, an expert on trapdoor spiders and her beloved West Australian Wheatbelt, passed away aged 90.
- The American Arachnological Society’s 2019 annual meeting will be held June 16–20 at Washington and Lee University in Lexington, Virginia.
Research & Observations
Every month, arachnologists discover new things about their favourite animals.
Silk and Webs
- The uloborid spider Hyptiotes stretches out its triangular web, spring-loaded to catch prey. Features the truly brutal quote “[The prey] might just die slowly as they start to feed on it.” (Paper.)
- Unlike creatures that sense vibrations through the air, ground, or water, orb-weaving spiders can directly control how vibrations are transferred by fine-tuning their webs. Here’s a look at all the different ways they do this.
- The purpose of stabilimenta, silk decorations in spider webs, is a long-standing debate in arachnology. Observations of a spider-hunting Australian assassin bug suggest the stabilimentum might distract or confuse predators.
- “A puzzle within a puzzle” wrapped in a mystery inside an enigma, or, why does the orbweaver Micrathena duodecimspinosa knock out some of its lines while building its web?
- Atypoid spiders build an amazing diversity of webs — funnels, sheets, “purses”, trapdoors, turrets, and “silken collars.” A new study has discovered that atypoids split from other mygalomorphs (like tarantulas and trapdoor spiders) as early as the Triassic, and that the common ancestor of the group had a “funnel-and-sheet” web.
Homes & Diets
- Less about food and more about how to get to the restaurant really efficiently — the latest paper from David Hill examines how jumping spiders take complex paths that require detours that take their goal out of sight. Complicated diagrams, but less math-y than previous articles.
- In a Maine bog, two kinds of jumping spiders — the bronze jumper Eris militaris and the ant-mimic Synageles canadensis — manage to live side-by-side in pitcher plants by preferring different parts of the flower.
- Citizen science data shows that three kinds of Argiope orb weavers prefer separate habitats in the Iberian peninsula.
- The Okinawan fishing spider Dolomedes orion eats better than I do! Its varied diet includes crustaceans, frogs, and even lizard.
- For cobweb spiders in the deserts of Arizona and California, long lines of seed-harvesting ants are an all-you-can-eat buffet. But these ants will rescue each other from cobwebs and even tear webs down! (Paper.)
- Here’s another ant-eating cobweb spider. It’s figured out how to successfully capture ants — but it will snack on other insects too.
- Where do Grammostola rosea live around Santiago, Chile?
Regional Surveys
- Scientists with the Circumpolar Biodiversity Monitoring Program (CBMP) have been working to understand what spiders live in Arctic regions and how they are affected by climate change. Compared to that for vertebrates, there is very little data on spiders in this part of the world — a problem the CBMP is hoping to fix.
- Work on a DNA barcode library for the spiders of Pakistan has turned up many possible new species, with very little overlap with other countries’ libraries.
- “Very little is known of Nigerian spiders”, but this national inventory is an important first step.
- The tropical mountain cloud forests of Mexico are fantastically biodiverse but poorly studied. A new paper surveys the rich spider populations of El Triunfo Biosphere Reserve and how they vary based on stratum and season.
- Mexico’s Cuatro Ciénegas Basin has an awful lot of wolf spiders compared to other parts of the Chihuahuan and Sonoran deserts. The basin is also home to 12 species of scorpion, which may be threatened as the area becomes more and more desert-like.
- From 1903–1905, Leonhard Schultze collected many spiders in western and southern Africa. A hundred years later, a lot of those spiders have been renamed and reclassified — a new paper updates Schultze’s findings based on what we’ve learned since.
How it’s Made: Spiders
- In many spider species, males are smaller than females. One possible explanation is that smaller males are more agile. But, at least in Nephila, it turns out small size doesn’t make males any better at getting around.
- Isn’t it amazing that a jumping spider the size of a dime has vision as acute as a pigeon’s? Isn’t it even more amazing that baby jumping spiders are even smaller and can see just about as well? The latest from the Morehouse Lab investigates how they fit those big eyes into their cute teeny little heads.
- As a male Parasteatoda tepidariorum house spider matures, his pedipalps transform from basic leg-like appendages to intricate organs that can fit into females’ genitalia like a key into a lock. The process is kind of like how a caterpillar turns into a butterfly.
- Arachnology and computational fluid dynamics, together at last. These researchers modeled a spider’s hydraulic leg joint.
Communication
- A study of the mating habits of the riverbank-living Tetragnatha straminea offers many interesting observations, like how fighting — and mating — ramps up later in the season, as well as how T. straminea’s behaviour differs from its close cousins T. extensa, T. elongata, etc. (PDF.)
- When courting, male wolf spiders use both visual and vibratory signals. These researchers presented female wolf spiders with choices between different signals — vibration and visuals, both vs. vibration, and both vs. visual — to see what they preferred.
- Yes, peacock jumping spiders have eye-catching, brilliant hues; but their deep “super black” markings really make those colours pop. Can it be a coincidence that birds of paradise have evolved the same contrast?
- A surprising number of arachnids make noise! They stridulate — rubbing textured bits of their bodies together, like crickets. Here’s a look at stridulation among opiliones in the family Cosmetidae. Turns out they sing for their own safety, not for love.
- Don’t let the above news items fool you! Spiders don’t just use sight and sound to talk to each other — smell matters too. Andreas Fischer goes in-depth on how spiders use pheromones and scent cues, and how much more there is to discover. (PDF.)
Venoms
- Over the past ten years or so, deaths from Tityus scorpion stings have risen sharply in Brazil. Rapid urbanization without adequate infrastructure has given these adaptable scorpions many places to live alongside humans.
- Possibly related: scorpions may be repelled by rosemary oil. Strangely, not the “active ingredient” alone. Interesting.
- An analysis of the wandering spider Cupiennius salei’s RNA identifies neurotoxic proteins and peptides in its venom. Learn more than you ever wanted to know about how a spider makes venom in the first place, from DNA to end product.
Parasites
- Up for some really gnarly parasites? Of course you are! Here’s a unique example of mermithid nematodes parasitizing orbweavers in Thailand.
- AAAAAAAAAAAAHHHHHHHHH: this kid from Connecticut had a tick in his eardrum. Don’t tell Stephen King. (Doctors removed it and he’s fine.)
Taxonomy
Who’s related to whom, and how.
- Okay, so first, horseshoe crabs (Xiphosura) were a sister group to arachnids. Then horseshoe crabs were arachnids. Now, according to this new analysis, they’re not arachnids. Also, mites and ticks should be grouped together, which would make them the biggest group of arachnids, with even more species than spiders! This will undoubtedly not be the last word on chelicerate relationships, so stay tuned for more developments.
- “Giant Goblins above the waves at the southern end of the world” sounds like an amazing fairy tale, but is actually the story of how orsolobid spiders made it to New Zealand. These “giant goblins” are quite small (2–6mm), but are twice the size of regular goblin spiders (1–3mm; Oonopidae).
- Researchers studying the Australian white-headed spiny trapdoor spiders (Euoplus sp., mcmillani group) found males of 3 new species, but no females. Unlike males, which roam about looking for mates, the ladies live their entire lives within their burrow, making them very hard to find and study.
- New ant-mimic jumping spiders have been found in Papua New Guinea! Except some members of the group appeared to have evolved away from mimicry and look like normal jumpers! Super weird.
- Avast! 3 new species of pirate spiders have been found in China. Pirate spiders have evolved to catch and eat other spiders, often by plucking at the prey spider’s web and mimicking a struggling insect. When the web’s owner comes to investigate, the pirate raises the Jolly Roger and pounces on its meal.
- What used to be thought of as different species of jumping spider have now been consolidated into one, Rishaschia amrishi. How did this happen? The old species were only known from the males, which all looked different. Turns out that there is a lot of variation in how R. amrishi males look!
- Scientists use one individual — the “type specimen” — to describe each species. In some cases, those original descriptions might have missed some details that can help identify the animal. Four palp-footed spiders (genus Palpimanus) have had their type specimens re-examined, and updated info is now in the World Spider Catalog.
- Two new species of pseudoscorpions were discovered in the leaf litter of a Mexican oak forest. Pseudoscorpions are so tiny and understudied that wherever scientists look, new species are lurking.
- Another new species of pseudoscorpion has been found in India and added to the genus Metawithius. However, another Metawithius species has been found to be crashing the family barbecue while unrelated, and has been transferred to a different genus.
- In more pseudoscorpion family drama, all species of the genus Indogarypus have been told they actually belong in the genus Geogarypus.
- Brazilian scientists explored 239 caves and found many rare species of pseudoscorpions. Unfortunately, many of these caves are threatened by mining, dams, farming, and unregulated tourism.
- Where did all those pseudoscorpions come from, anyway? A new genetic study has found that pseudoscorpions—and there are 3700 species of ’em today!—began diversifying sometime between the Devonian (420–359 million years ago) and the Carboniferous (359–300 million years ago). The ancestral pseudoscorpion living back then didn’t have venom, which later evolved during the Mesozoic (252–66 million years ago).
- There is a new species of vinegaroon from Vietnam! (How do you say vinegaroon in Vietnamese? “Giam,” according to Google.)
- Seventeen (!!) new species of huntsman spiders, all in the genus Sinopoda, were described in China!
- Expeditions into the Dalmatian karst caves of Croatia have discovered a new species of harvestman, named Lola konavoka. The study also compared other European cave-dwelling harvestmen, and noted that the more adapted you are to living in caves, the smaller your population and the greater the risk of extinction.
Corrections, ideas, and items for next month’s edition are welcome! Leave a comment or drop us a (silk) line on Twitter at @arachnofiles.
