It’s not what you say, it’s how you vibrate your opisthosoma while you’re saying it.
– Ancient Peacock Spider Proverb.
We humans tend to think very highly of our behavioral complexity. Two people out on a date are a jaunty jamboree of visual, olfactory, and linguistic cues simultaneously given and received. And yet, were a peacock spider to behold our clumsy efforts, he would find them even more staggeringly underwhelming than, let’s face it, we often do ourselves.
Just watch this guy work:
Judged purely visually, these animals already have some next-level game going on, but the freaky-cool visual is really only half the story. To get the rest, we need two things: a laser and Madeline Girard.
Girard was born in 1986 and grew up surrounded by nature in a small upstate New York town. Her parents encouraged her scientific and artistic inclinations equally with the result that, like Fabiola Gianotti and Sofia Kovalevskaya, she feels comfortable in both worlds and continues to develop her artistic side even while regularly crossing from Berkeley to Australia and back again in pursuit of her scientific research.
In college at Cornell, she was like many undergraduates who are interested in Science! generally, but aren’t quite sure what part of science to devote themselves to. She studied astronomy, physics, earth science, and biology in turn before a class in animal behavior set her on the path of her life’s work. “It was my absolute favorite and I was so surprised to learn that I could make a career out of studying wacky animal behaviors.”
That work has taken her from one fascinating behavior to another, answering basic questions with super snazzy tech. One of the projects she worked on was determining what makes hummingbirds hum. For this study, hummingbird feathers were placed in a wind tunnel and their motions analyzed with a scanning laser Doppler vibrometer. By changing the wind speed and feather angle, the team was able to determine the different modes of vibration of the feathers and their associated frequencies.
They found that the feathers vibrated in one mode until a threshold air speed or angle was reached, at which point the feather would, in the space of a millisecond, flop to a different vibrational mode and frequency. They then tested the feathers on a shaker rig for resonant states and found a correlation between the natural vibrational frequencies of a feather and the oscillation modes the feather jumps between when pushing through the wind. In effect, as it glides about, the air plays the hummingbird like a violin.
That is rather neat.
But the neat has hardly started. Let’s talk about honey bees. Honey bees belong to a category of animals including ants and wasps where one queen rules the colony. With that societal structure comes a choice: do you mate with only one male and gain the altruistic advantages that come with a closely related colony, or with multiple males to produce a hardier and more diverse genetic pool? Previous studies had indicated that polyandrous queens gave birth to societies much more efficient at collecting resources than those from monogamous monarchs.
Scout bees who seek new food sources are supposed to, upon finding one, return to the hive and perform a waggle dance to let the rest of the colony know the richness, distance, and direction of the source. It takes about eight cycles of the dance for all of the information to be conveyed, but scouts from monogamous queens (let’s call them M-Scouts) often give up before then. Polyandrous-derived scouts (P-Scouts!), for some reason, dance longer, and tend to deliver the whole message, according to previous research.
But what is a dancer without an audience? While other studies shored up the data on p-scouts’ superior dance performance, Girard and her team shifted focus to the bees observing the dance. Were p-watchers better at observing and acting than m-watchers? They built a greenhouse with a resource-poor hive to find out, complete with a camera focused on the bees’ dance floor.
Yes, the place in the hive where the bees do their waggle dance is actually called the Dance Floor. They could have called it something like the Resource Information Conveyance Sector, but instead they made a decision as a scientific discipline to call it the Dance Floor. That is also rather neat.
They tracked how many watchers gathered around a dance, how long they followed it, and what they did afterward, and found that not only were p-scouts more diligent in their waggling, but p-watchers observed longer and exited the hive in greater numbers after the dance. So, polyandrous colonies breed greater attentiveness and efficiency all around, which opens the door to investigating the question of Why.
That wasn’t Girard’s question to answer, however, which brings us back to our mating superstar, the peacock spider. It’s an interesting case of not letting human bias interfere with the data collection and interpretation process. What we, with our visual bias, interpret as of prime significance might not be what spiders care about. So, Girard and Team set out to capture the peacock spider’s mating ritual in all its modes, employing our good friend the laser vibrometer in the process.
At first, they aimed their high speed cameras and vibrometer at a female-male couple only to be defeated by the difficulty of tracking the quick-skittering spiders’ movements. So, what’s the next best thing? Why, mounting a dead female on a pivoting cork, of course!
It worked in Weekend at Bernie’s and, fortunately, it worked on the male spiders too, who courted their prospective corpse brides with assiduity and pep, displaying a combination of leg movements and fan dancing matched only by the rich vibrational signals they produced from their abdomen, which included at least three different distinct patterns used at different moments of the ritual.
“Cool, but why do we care?”
Well, firstly, we’re humans and caring is just what we do, but more importantly, being able to catalogue the components of a behavior is the first step to being able to know how those different components are weighed and evaluated. Does the female consider all these different pieces as a whole, or does each behavior send a different, vital bit of information? Knowing that, we can learn more about the relative evolutionary advantage of complex behavior, and better understand thereby the rich tradition of natural history stretching from archaebacteria to us.
Girard has since moved on to studies involving sexual signaling in crickets and, if the density of her first scientific years is any indication, we can look forward to a steady stream of new insights into the groovy weirdness of the animal kingdom for some years to come, capturing behavior with more than human eyes guided by precisely, and magnificently, human curiosity.
FURTHER READING: Madeline Girard recommends Animal Behavior: An Evolutionary Approach, Tenth Edition to anybody wanting to have a start in studying animal behavior. And, while you’re waiting for that to arrive, why not hop back to Women in Science Episode 7, and Carolynn Smith’s work with the multi-modal majesty of chickens!