Nature Lab

Assessing Spider Diversity

Biologists surveyed spiders in Spring Creek Watershed priority geography

Not many people go outside hoping to see spiders, but Reese Worthington has been trying to find as many spiders as he can. Worthington, a natural history biologist for MDC, has been inventorying spiders as part of MDC’s landscape assessment and monitoring initiative.

Spiders may not be the first thing you think of when it comes to conservation, but they are vital to our ecosystems and part of a thriving landscape. Spiders at large, however, are not well studied, and global research indicates that spider numbers are declining.

“We need to know what we have before we start to lose potentially even more species,” Worthington explains.

During 2022, Worthington and an assistant surveyed spiders on the Spring Creek Watershed priority geography in northeast Missouri. Using four collection methods, they sampled spiders from a variety of habitats within the 46,795-acre area.

Spiders are difficult to identify to the species level and often microscopic examination is necessary. So, specimens were preserved and brought to spider expert Hank Guarisco in eastern Kansas for identification. About 6,900 specimens were collected. Identifying all of them will take time. So far, 166 species have been identified. These include 16 species never before recorded in Missouri, representing 13 different families of spiders.

“The coolest thing,” Worthington says, “is that we have found two new species undescribed by science. Hank will be writing those up as scientific publications.”

Knowing which species are present can inform land managers if they should alter any practices to accommodate the life history of rare or less common species. For instance, they can wait to do a controlled burn until after spider eggs have hatched and the spiderlings have made their way into the world.

Although collecting at Spring Creek Watershed is done, Worthington will continue to explore spider diversity in the state. Collecting spiders in the Ozarks is one of his upcoming projects.

At a Glance

Spiders are one of the most abundant and diverse predator groups on the planet, living in many habitats and employing a variety of hunting strategies.

• More than 45,000 spider species worldwide
• More than 3,500 species in North America
• About 450 known in Missouri so far

Catch prey in web

Funnel web spider

Wander and hunt

Jumping spider

Wait and ambush

Crab spider

Hunt on water

Fishing spider