Professor Says Education, Not Eradication, Is Best Policy for Spiders
Grant, a professor of biology at Davidson for the past 31 years, spent the spring semester sabbatical as the first "professor in residence" at Discovery Place in Charlotte creating a spider education kit for Charlotte/Mecklenburg high school students. He hopes greater familiarity with spiders will help students appreciate the invaluable work they do in keeping down insect populations, and to show students the rich diversity of spiders found in the metrolina area. "There are about 100 different families of spiders worldwide, and about 35 of them can be found here," he explained. "Without all those spiders, we would be up to our eyeballs in insect pests."
Grant is probably Mecklenburg County's leading spider expert. He and his students have collected more than 3,000 specimens of spiders during the past three decades, and about 12 years ago he began storing those specimens at Discovery Place. But they have been kept in cases and closets, inaccessible to the public. Recognizing Discovery Place's mission to promote "hands-on" science, Grant spent about 40 hours a week last spring working with the museum's collections manager, Dawn Cobb, and collection specialist, Shannon Stober, to find a way to help students learn about spiders by taking the collection to them.
Spider Kits "To Go"He created 16 of the spider kits, packed four each in four cases. Each kit includes instructional sheets for both students and teachers. The "good stuff" inside is a baggie full of plastic arthropods and 18 vials of real spiders preserved in alcohol. Discovery Place provided financial support for the project to purchase the necessary glassware and printed materials, and the spider specimens were taken from the collection. Each case will be loaned free of charge for a two-week period to a Charlotte/Mecklenburg school system high school biology teacher beginning next school year.
Students begin the lesson with the bag of plastic arthropods, a phylum which includes everything from spiders, ticks and fleas to grasshoppers, beetles, scorpions, crabs and lobsters. A one-page "key" helps them identify each animal by answering questions such as the number of legs they have, the distinction of the division between their body parts, and the presence or absence of wings. "It gives them the experience of making identifications with something large enough to handle, then they can go to the vials and begin examining the real specimens," Grant explained.
The specimens in the vials were carefully chosen to represent 11 different families of spiders commonly encountered in this area, and to demonstrate the range of shape, color and adaptations of behavior that make them such good predators of small insects.
Not Your "Garden Variety" Spider...Grant can speak extensively and lovingly about each spider. The most frequently recognized spider in each collection is the black widow, but the most common is probably its close relative, the common house spider.
The grass spider builds a closely woven sheet web that disappears down a tight funnel into the grass. It waits in the funnel for prey, a position that allows it to run out onto the web if a small insect lands, or to flee down the funnel and into the grass if a large and dangerous insect is caught.
The largest specimen is the two-inch black and yellow garden spider. It is an orb web builder sometimes referred to as a "signature" spider because legend has it the spider sometimes writes the names of people destined to die with its zig-zag silk thread.
The collection includes three hunting spiders, but they catch prey by very different means. The wolf spider literally runs down its prey, while the jumping spider stalks its prey much like a cat, creeping stealthily until it is close enough to leap upon it. Both those spiders have very good eyesight. But another hunter, the crab spider, has very poor eyesight. It sits motionless on top of a flower until an insect lands on the flower, then the spider grabs it. Yet another hunting spider, the fishing spider, dives through the surface of the water to catch small minnows and tadpoles.
The nursery web spider lays eggs inside a sack inside a dense ball of webbing, so that her children cannot disperse immediately when they hatch. She watches over them by guarding the ball until they are old enough to fend for themselves.
The young nursery web hatchlings, and many other spiders, display a marvelous ability to disperse themselves across the landscape by "ballooning." When they are ready to go, they sit in an exposed place and play a silk thread out into the wind until the pull of the wind carries them into the air. Some only travel a short distance, while others have been caught in nets dragged behind airplanes at 5,000 feet!
A Lesson in Spider AnatomyGrant explained that the students using the kit will pull these specimens carefully out of the vial and place them in alcohol in a dish underneath a dissecting microscope.
Grant says the exercise not only teaches students about spiders, but teaches them about the scientific method. They learn the process of biological identification that applies not only to spiders, but also to plants and all forms of animals from microscopic to mammalian. "When scientists find an unknown specimen, they refer to key sheets to try to identify them," he said. "The key sheet with the spider kit is intentionally much simpler than one used by professional scientists, but the process of using it is the same."
"Creepy" CuisineFor students who want further experience with spiders, the kit includes information on how to catch spiders, where to catch them, where to get the materials needed to catch them, and how to preserve them. He does not include instructions, however, for cooking them - which actually occurs in some cultures. "They've very high in protein because they eat insects, which are also high in protein," Grant explained.
Grant has personally caught thousands of spiders, and has never been bitten because he doesn't try to catch them by hand. Though the only local spiders whose bite can be dangerous are the brown recluse and the black widow, he notes that all spiders will try to bite the hand that catches them. "Most spiders can't physically bite people, though, and those that can generally don't have enough venom to irritate you any more than a mosquito bite," he said. "They're in far more in danger from us than we are from them."
Save the Spiders!In that spirit, he doggedly preaches the necessity for spider conservation. He practices that by catching specimens only during the fall, after females have laid their eggs and just before they are destined to perish in the winter chill. He also practices it in his own home by leaving webs alone that he finds behind furniture, and relocating other spiders outside rather than killing them.
In addition to his work this semester at Discovery Place, he has recently taken on the task of helping identify about 2,000 spiders in the collection of the Schiele Museum in Gastonia, and spent almost 100 hours at that endeavor so far. Besides the spider course he teaches at Davidson once each year, he also teaches several courses and seminars in marine biology and leads a semi-annual course in that subject that travels up and down the east and gulf coasts.
Davidson College is a highly selective independent liberal arts college for 1,750 students. Since its establishment in 1837, the college has graduated 22 Rhodes Scholars and is consistently ranked among the top liberal arts colleges in the country by "U.S. News and World Report" magazine.