Meet the Scientist Studying the Scary Speed of Spider Jaws
Learn how arachnologist (that’s spider specialist to you and me) Hannah Wood uses the fossil record to track the evolution of these misunderstood critters.
PLUS! Bonus creepy spider facts about swallowing spiders in your sleep. Gulp!
Smithsonian scientist Hannah Wood rifles through leaf litter in the Philippines. She uses a straw-like instrument to gently blow away detritus and uncover spiders. (Photo bt Stephanie Stone)
Spiders get a bad rap. Especially around Halloween, when spiders and other creepy crawlies are seen as a spine-chilling symbol of spookiness. Arachnaphobia, or the fear of spiders, is quite common, afflicting 3-15 percent of people.
But Hannah Wood has nothing but affection for these shy creatures. As the curator of Arachnida and Myriapodia at the Smithsonian National Museum of Natural History, Wood gets up-close and personal with spiders out in the wild and in the lab.
While thinking about a spider’s fanged jaws may give some people the heebie-jeebies, for Wood, it’s a source of endless fascination. “Being educated about them helped me be less afraid,” she said.
Wood has traveled to Madagascar, Chile and South Africa in search of spiders to learn more about their traits, behaviors and geographic range. But she never envisioned herself as a globe-trotting arachnologist in her younger days. In college, she studied literature. But she developed a passion for science after taking an insect taxonomy class “just for fun.” Her winding career path eventually led her to the forests of Madagascar, where she first fell in love with spiders.
Wood’s research investigates the evolution of spider morphology – how different species developed the traits they have today. She uses the fossil record to inform her observations of present-day spiders. This helps her determine when and where certain traits emerged throughout evolutionary history. Her current work focuses on a specific group of spiders whose jaws have evolved to chomp down on prey in the blink of an eye. Wood gave them their common name – the trap-jaw spiders – because of this mechanism.
A newly described Mecysmauchenius species of spider that attacks its prey with lightning-fast predatory strikes. (Photo by Hannah Wood,) NMNH
In this month’s installment of Meet a SI-entist, Smithsonian Voices chatted with Wood to learn how her work is untangling the web of arachnid evolution.
Many people are terrified of spiders. But are these animals actually dangerous, or just misunderstood?
When I first started studying insect taxonomy, I learned about the mouthparts and stingers of insects – all the ways that insects can harm you. Being educated about that actually helped me be less afraid, because I knew which species I could safely pick up and which I couldn’t. It’s the same with spiders. Almost all spiders do have venom for killing their prey, but the vast majority of their venoms are harmless to humans, and they are so shy that they’re never going to harm you.
My motivation for studying spiders is understanding their diversity. There are thousands of species of spiders, and half of them haven’t even been documented or seen yet. Spiders are also important to their local ecosystems. They play a crucial role as predators of arthropods, soil vertebrates and small flying insects. If you remove spiders from the ecosystem, there’s going to be downstream effects. We definitely don’t want to lose them.
How do you use the fossil record to inform your research?
An ancient spider preserved in amber. (Photo courtesy Hannah Wood, NMNH)
A lot of biologists who study the fossil record are looking only at fossils, in the same way that those who study living groups are only looking at living organisms. But there is something that happens when you start to look at both together – it gives you a whole different perspective.
Your research mostly focuses on one superfamily of spiders: the palpimanoids. Why did you choose to study them?
The palpimanoids are an incredibly interesting group, especially for people studying the evolution of spiders. They have an extensive fossil record that I would argue is one of the best among spiders. It goes back 170 million years. Palpimanoid fossils appear in amber from the Dominican Republic, the Baltics, India, and Burma, as well as in traditional fossils from China and Brazil.
Their fossil record suggests that at one time, the palpimanoids were much more abundant and widespread. But as more modern spiders evolved, palpimanoids became restricted to smaller geographic areas and ecological niches. Over time, this caused many different, highly specialized palpimanoid species to evolve, which is why we have the diverse group we see today.
Wood searches for spiders during an expedition in Madagascar. (Photo by Hannah Wood, NMNH)
Many of them specialize in preying on other spiders, and they have evolved behaviors and morphologies to help them attack their prey. In particular, they’ve evolved some really interesting mouthparts to keep themselves safe when targeting another spider. The most exciting thing I’ve ever discovered was the trap-jaw spiders. They have unusual morphologies, but no one had ever looked at why they have these weird long necks and jaws.
I began recording their feeding behavior with a high-speed video camera, and found that some species had evolved a mechanism like a catapult to produce these extremely fast jaw movements – the fastest movements among arachnids. So, the palpimanoids are a really interesting group for studying how trait evolution happens over time and how modern groups evolve.
An adult male specimen of Eriauchenius workmani, one of 18 species of new pelican spiders discovered and described by Wood in 2018. (Photo by Nikolai Scharff)
How do you locate the strange spiders that you study?
To find these spiders, you have to go to really healthy forests. You aren’t going to find them in degraded habitats. But the type of collection methods I use depend on where I am.
I preserve the specimens I collect in ethanol, then gather data about them in the lab. I will take a leg or two, and then extract and sequence its DNA. I’ll take images of the specimens to perform morphometric analysis, which is an analysis of their shape that allows me to compare the structure of different traits. I also do CT scanning, which is equivalent to an MRI for humans, to look at the internal musculature of a spider’s mouthparts. Right now, I’m working with collaborators to model those muscles. That will allow us to understand how they function, and compare among all these different species to get an idea of how they are using their jaws. One specimen goes through a lot!
Hannah Wood pulls out a jar of spider samples in the museum’s entomology collection. (Photo courtesy Hannah Wood, NMNH)
In my home state of Maryland, there are several local species, including daddy long-legs and wolf spiders, that I collect and study in the lab while it is still alive. I record this species with a high-speed video camera so that I can see the mechanics of their mouthparts in action. I analyze those videos in order to quantify the movement and compare it to how the mouthparts of other species function.
Why is it important to understand and document the evolution of spiders?
Arachnology is falling behind compared to what’s known about a lot of other animal groups. Vertebrates, for example, have been studied much more extensively than arachnids. It’s only been in the last five or six years that arachnologists have been able to make progress toward constructing a phylogeny of life for all spiders thanks to new molecular research methods.
As she surveys for spiders, Hannah Wood encounters all kinds of critters, including this chameleon in Madagascar. (Photo courtesy Hannah Wood, NMNH)
This research also has implications outside of the field of biology. Spiders are like these little hydraulic pumps – they have high internal pressure and they use hydraulics in a lot of their movements. Understanding those mechanisms can provide insight for the field of robotics, or other applied areas. I think arachnology is going in a really good direction right now, and there’s going to be a lot more we can learn from arachnids now that we’re finally able to ask those bigger questions.
Ellyn Lapointe is an intern with the Smithsonian’s National Museum of Natural History Communications and Public Affairs office. In addition to her role at the museum, she is pursuing her masters in Science, Health and Environmental Reporting at NYU’s Arthur L. Carter Journalism Institute. Her freelance reporting mainly covers environmental topics such as ecology, climate, and agriculture and has been published in Sierra Magazine, Your National Forests Magazine, Insider, and other outlets. When she isn’t writing, Ellyn can be found birding, skiing, or hunting for the best ramen in NYC.
This post was originally published by the Smithsonian magazine blog, Smithsonian Voices. Copyright 2023 Smithsonian Institution. Reprinted with permission from Smithsonian Enterprises. All rights reserved. Reproduction in any medium is strictly prohibited without permission from Smithsonian Institution.
Do you really swallow spiders in your sleep?
(Linnea Bullion/For The Washington Post)
You’ve probably heard the nightmarish myth that up to eight spiders per year will crawl into your mouth while you’re sleeping. But according to NMNH entomologist Floyd Shockley, these shy arachnids want nothing to do with humans, so swallowing even one would be an unlikely occurrence. Click the link below to learn why the odds are against this unusual urban legend.
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Posted: 6 November 2023
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