It's helping them spawn tons of spider eggs, too.

(Elizabeth Lowe)

Great news for people who perform LeBron-class vertical leaps when they see a spider: The unnatural environment of cities seems to be inflating these creatures like bulging eight-legged balloons, according to new research.

Of course the focus of today's study in PLOS ONE is already a giant, nightmarish ball of eyes, legs, and fangs: Nephila plumipes, an orb-weaving spider whose massive colonies can cover the sky with webs the size of circus nets. Elizabeth Lowe and her colleagues at the University of Sydney have been monitoring the species around the city as well as the 'burbs, and they've noticed a stark difference in the urban spiders: Compared to their bushland-dwelling cousins, they are bigger, pack on more body fat, and have heavier ovaries. That last finding suggests these guys are great at having tons of spider babies. 

(Elizabeth Lowe)

Lowe got in touch to explain how she entered the world of these swollen spiders. "I'm interested in the way that living in cities affects wildlife," she says. "Spiders are a great taxa for this because they are very diverse and some of them do particularly well in cities." (Lowe isn't the first to probe the link between cities and arachnid physiology; for instance, a 2013 study found that certain species thrive in vacant lots converted to urban gardens.)

Lowe believes two things about cities are influencing these critters' bulk: temperature and an abundance of insects to eat. "Hard surfaces and lack of vegetation lead to the well-known 'urban-heat island' effect, with more heat retained than in areas with continuous vegetation," she says. "Higher temperature is associated with increased growth and size in invertebrates."

As for the endless buffet of nourishment, the spiders can thank the light beaming from Sydney's street lamps, office buildings, and parking lots. "Urban lighting also may be a contributing factor as it attracts insects and means more food for spiders in those environments," Lowe says. "This increase in prey would result in bigger, heavier, more fecund spiders."

While Lowe's research was confined to orb weavers, it's a good bet that more spiders are exploiting the advantages of cities, too. As her study asserts: "Other web-weaving spiders are also known to thrive in urban environments and it is likely they are responding to similar modifications to the natural environment."

Elizabeth Lowe

 

About the Author

Most Popular

  1. Rows of machinery with long blue tubes and pipes seen at a water desalination plant.
    Environment

    A Water-Stressed World Turns to Desalination

    Desalination is increasingly being used to provide drinking water around the globe. But it remains expensive and creates its own environmental problems.

  2. a photo of a highway
    Transportation

    Americans Are Spending Billions on Bad Highway Expansions

    PIRG’s annual list of “highway boondoggles” includes nine transportation projects that will cost a total of $25 billion while driving up emissions.

  3. Transportation

    CityLab University: Induced Demand

    When traffic-clogged highways are expanded, new drivers quickly materialize to fill them. What gives? Here’s how “induced demand” works.

  4. Design

    What Cities Can Do to Help Birds and Bees Survive

    Pollinators—the wildlife that shuffle pollen between flowers—are being decimated. But they may still thrive with enough help from urban humans.

  5. Four young adults exercise in a dark, neon-lit gym.
    Life

    Luxury Gyms Invite You to Work Out, Hang Out, Or Just Work

    With their invite-only policies and coworking spaces, high-end urban gyms aspire to be fitness studio, social club, and office rolled into one.

×