Undergraduate Research at Virginia Tech

Arachnophillia? Sophie’s Spiders

By Sarah Hawes, biology

Now a junior, Sophia Bous began her quest to get involved with research at Virginia Tech two years ago. She sent out about 16 applications to research positions her freshman year (!), but it was while discussing lecture material outside of class with her Biology Principles professor, Brent Opell, that she got the personal invitation that launched her current research participation. Bous's start is evidence that making yourself seen and heard -- and maybe having a little hard-earned good karma -- can really pay off.

Bous began her research with Opell working on a project comparing two species of New Zealand spiders, and liked it so much she is still with the same lab. In a recent interview, she described how fascinating the life processes of spiders can be. Did you know that fertilization does not occur during copulation in spiders? The female stores the sperm, and fertilizes the eggs herself as they are laid. Also,unlike human fetal provisions, the female spider provides her eggs with a large amount of yolk to be consumed by the developing embryo.

Bous' most recent project has been to investigate possible developmental rate differences between two orb-weavers (the little guys responsible for such classic web designs as those found in Charlotte's Web and Spiderman). Specifically, she worked with Cyclosa turbinata and Uloborus glomosus. These research subjects can be found in backyard Blacksburg.

Although both species are local orb-weavers and grow to a similar size, the eggs of one species hatch in the summer, and one in the fall. This difference in reproductive scheduling lead researchers to ask, "Do the spider embryos develop at different rates?" They hypothesized that Cyclosa spiders hatching late in the season would show more rapid development in the egg than summer-hatching Uloborus. This would ensure that Cyclosa had ample time to hatch and feed before winter.

In the Fall semester, one of Bous' first duties was to collect Cyclosa egg sacks from the wild (we call it campus) to be examined in the lab. Uloborus spiders had been collected over the summer and kept in large plastic boxes to produce egg sacks. All egg sacks were incubated at 25 degrees C with moist cotton for humidity.

Spider egg development was mapped into five pre-hatching stages. These stages were observed and graphed against the age in days of the egg sack to give developmental rates for each spider type. Bous maintained incubation conditions, and also viewed eggs under a microscope to determine their developmental stages. She describes the task of egg stage identification as scary at first, exclaiming that the microscopes make the developing spiders and the "explosion of baby spiders" after 14 days "look like little aliens." She warmed up to the task quickly, and speaks excitedly about her work with spider embryology.

As it turned out, the developmental rates between our two orb-weavers were statistically similar. Bous pointed out that a possible fault of the experiment could lie in the fact that while 25 degrees C is a good average temperature for incubation, no attempt was made to imitate naturally occurring fluctuations in temperature over the course of a day.

Something else interesting to note before concluding that these spiders develop at the same rate: Uloborus glomosus belongs to a more primitive family of orb-weaving spiders that produce dry, fuzzy prey capture thread from a spinning plate, called a cribellum. In contrast, Cyclosa turbinata is a more advanced orb-weaving spider that has lost its cribellum and spins capture threads that have small droplets of wet adhesive material. When a Uloborus emerges from an egg sac, its cribellum is not formed and it can not produce capture threads until it molts (sheds its exoskeleton) and enters the next developmental stage. Cyclosa can begin making capture threads as soon as they leave the egg sac. So while Cyclosa hatchlings can weave a nasty capture web on day one, Uloborus hatchlings have to make due do with juvenile webs that lack sticky capture threads until after they molt.

Bous created a tidy student presentation of her research in PowerPoint with plenty of "little alien" pictures - very cool.

Through first hand experience, Bous discovered some of the concerns that arise in a research setting. She says that while it was interesting and fun, it could be stressful. You're not always sure what the best approach will be; do you collect more samples? Or move on with the research? Trying to keep the fragile eggs moist was frustrating at times. On occasion, two egg sacks would merge and Bous would open one half of a sack, identify the developmental stage, and then discover a clearly different stage of development in the other half.

Overall, Bous described her research as "super fun, really cool," and interesting in part because "not many people work with spiders." That's true. Bous has found that she enjoys embryology and hopes to work with babies (maybe human) for a career someday. She has also worked at the Genetics & IVF Institute in Northern Virginia.

Learn more about Brent Opell's Lab.