Darwin’s Bark Spider

Facts & Identification

Latin Name

Caerostris darwini


Females are mostly black with white hairs, while males are lighter in color. With this species of spider, females are much larger than the males. In fact, the females weigh about ten times more than their male counterparts. Males have a body length of about 6mm, while females range from 18-22mm. The spider is aptly named, as its camouflaged body greatly resembles tree bark.

Behavior, Diet & Habits

Darwin’s bark spider is an orb-weaver spider that boasts two remarkable headlines—its silk is the toughest biological material ever studied and its web creations have been dubbed the largest in the world. While Darwin’s bark spiders’ webs are harder to find compared to other spiders, the silk is twice as tough as other spider silk and over ten times tougher than Kevlar.

The spider constructs its web over rivers and lakes, putting itself in a unique position to capture dragonflies, mayflies and other prey that fly over water. To make its enormous home, the female creates a bridge by riding an air current from one bank of the river to the other while releasing a steady line of silk. This line can span over 80 feet. Once the bridge is intact, she can return to the center and create a web orb up to 30 square feet in diameter.

More Information

Darwin’s bark spider and its super-web abilities are still extremely new to the scientific world. Scientists believe its silk could be used to create stronger materials for human use, such as stronger armor, netting and structures. Until then, Darwin’s bark spider is simply one of the natural marvels of the world.

What’s with the name?

The species was discovered in Madagascar in 2009 and was officially described 150 years after Charles Darwin’s The Origin of Species was published. Because of this, the spider was named in the naturalist’s honor.