What a tiny beach spider teaches us about habitat fragmentation, recovery
by Sydney Cromwell
The map just didn’t make sense.
Drew Hataway was studying the genetics of the Santa Rosa wolf spider, a small, white spider that lives on the beaches along the Gulf Coast. But the results were weird.
He kept finding that groups of these spiders would have very different genetics from their nearest neighboring groups, where he would expect them to be closely related.
Why wouldn’t these spiders be intermingling and sharing genetics with their closest neighbors? The answer came from an accidental click on Hataway’s digital map, revealing human development — roads, buildings, cities — instead of just terrain. While the spiders were geographically close, there were near-impossible barriers between them, showing up on the map in shades of concrete and asphalt.
“Spiders can’t go right through the middle of Panama City [Beach] or Destin,” Hataway said.
Hataway, a biology and environmental sciences professor at Samford University, has studied the Santa Rosa wolf spider since he was an undergraduate student in the 1990s. Along the way, he has discovered a lot about how human development — from cities to beach houses — has carved up the Gulf Coast’s sand dunes and harmed the health of dune-dwelling plant and animal species in the process.
Hataway readily admits that he didn’t start out as a fan of spiders; he was more interested at first in the opportunity to hang out on the beach in between his nightly research.
“Sunburn is the major threat, I suppose,” he said.
However, Hataway said two events changed his research plans: first, the professor he had been working with for the original research project died, handing Hataway the unused data just as he was preparing to graduate. Then, Hurricane Ivan struck in 2004.
With population data from before the hurricane already in hand, Hataway had a ready-made Ph.D. project to study how the spiders responded to and recovered from a hurricane, from the Mississippi-Louisiana border to St. George Island, Florida.
“Seeing these things come back from hurricanes is just awesome,” he said.
Since then, Hataway said he has come to appreciate his eight-legged counterparts.
“I am not a spider person — or was not. I am now,” he said. “… If you spend enough time with something, you can learn to appreciate it.”
The Santa Rosa wolf spider is “not that robust a species,” Hataway said, and not much is known about its life. The spider’s small body blends into the sand, and it uses its web to build burrows in the dunes. It will then wait for prey to pass by, with its front legs hanging out of the burrow, rather than wandering the sands.
Hataway said these sand burrows are “so extremely delicate” that they collapse every time he has tried to make a mold of them.
To get an idea of how many of these hard-to-spot arachnids live in the dunes, one of Hataway’s frequent tools is a flashlight. A structure behind the spiders’ eyes, called the tapetum, will reflect back the light, making them clearly visible at night.
“You can count them just looking at the eyes,” Hataway said. “… It’s just terrifying and/or really impressive, I suppose, depending on your bent.”
In studying the populations and genetics of the Santa Rosa wolf spider, Hataway said he has found that they weather hurricanes better and recover more quickly in places with uninterrupted sand dunes and plenty of sea grasses.
“The more pristine the habitat, the more the animals evolved to survive the hurricanes in these areas,” he said.
The genetics also show that, while there is diversity between the different groups of these spiders living along the coast, there was a “bottleneck” in the rate of that diversification that began around 150 years ago.
“[There] used to be this one contiguous group of populations, sort of exchanging migrants back and forth, and they aren’t anymore,” Hataway said.
Hurricanes can temporarily cause a species to lose some of its diversity, as the population bounces back from the storm. However, hurricanes have always been part of life in the Gulf Coast.
“These things have been surviving hurricanes the entire time they’ve been a species, so why would we expect that to be a problem for them?” he said.
The specific bottleneck that Hataway has been studying lines up near-perfectly with the time when people began developing homes and towns along the Gulf Coast. Plus, there were those strange genetic divisions he found between neighboring spider populations, which matched up with man-made interferences.
“Human development drives a lot of the biology we see down there [on the Gulf Coast] now. I think these species that live down there for hundreds of thousands of years, minimum, are now having to adapt to human encroachment,” he said.
And that puts the Santa Rosa wolf spider and endangered species like the Alabama beach mouse in direct conflict with coastal residents who want to live as close to the shoreline as possible.
“The beaches that recover the quickest are the beaches that have the healthiest dune systems,” Hataway said. “… The first thing these major developers do is remove the dune systems.”
Hataway’s most recent paper on the Santa Rosa wolf spider was published in December 2020. He hopes to expand his future research to the Mississippi barrier islands and Louisiana’s Chandeleur Islands, to learn more about how the spiders live in less developed areas.
Closer to home, Hataway has also researched how another wolf spider species, the tropical wandering spider, responds to a different kind of natural disaster: wildfires.
Through Oak Mountain State Park’s controlled burn schedule, Hataway has been able to study population differences before and after these fires. A forest is a more complicated ecosystem than a beach, but he said species tend to recover in waves, with the first species, like ferns and mosses, creating conditions that allow other plants and animals to rebound.
The tropical wandering spider’s population takes a hard hit in the first year after a fire, he said, but they usually are part of that second or third wave of recovery.
“They’re just doing their best to survive, and it’s just neat,” Hataway said.
The tropical wandering spider was also the subject of a Samford student’s research on the use of its venom as a potential antibiotic. Hataway assisted with this research, which involved milking the spiders for their venom (“which was real interesting,” he said) and then applying it to microbes to see if the venom kills them.
How do you milk a spider? Delicately.
Hataway said the spiders are anesthetized with carbon dioxide gas first, then an electrode stimulates the venom gland, causing the muscles to tighten up and squeeze out the venom.
Microbe resistance to typical antibiotics is an increasing concern for hospitals because of the possibility of creating “superbugs” that are hard to treat. Spider venom is just one of many treatment options being researched as new ways to fight infections.
While that Samford student has taken his venom research onward to his doctoral studies, Hataway said the project opened his eyes to the ways scientists are trying to adapt spider venom and silk to creating new drugs, clothes, pesticides and other products.
“I did not realize how many people were looking at this much-maligned group of organisms to try to find solutions to human problems,” he said. “… People hate spiders and people want to kill all the spiders in their house.”
That’s part of the problem: spiders are unlikely ambassadors for conservation.
“You can never get funding for anything you can’t make a stuffed animal out of,” Hataway said.
Even if they don’t have a face for fundraising, Santa Rosa wolf spiders are as much a part of healthy beaches as sea turtles and other popular species, and protecting their homes is just as important.
“We have to come up with a sustainable model for building along the coast,” Hataway said.
Main article image by Sarah Finnegan, courtesy of the Hoover Sun.