In Georgia, a black widow spider is enjoying a meal from a juvenile scarlet snake.
A new study has found that venomous spiders prey on snakes that are many times larger than themselves and often defeat equally venomous snakes.
The researchers found records of 319 spider predators, 297 of which occurred naturally in the wild. (The remaining 22 cases were in the laboratory.) About a third of those examples came from scientific observations published in journals, and the rest came from news or social media sites.
"The longer I've been working on this, the more I've realized that certain spiders can accomplish such incredible feats," said Martin Nyfiler, a conservation biologist at Base University, co-author of the study. He has previously reported that spiders feed on bats and other vertebrates.
On a thatched roof of the Eswatini Nicera Hotel, a live bat caught in a spider's web by a purple calamus.
Nyfiler and Whitfield Gibbons, a reptilian scientist at the University of Georgia, reported in the Journal of Spider science this month that snake feeding is so common that more than 30 species of spiders do so under natural conditions and 11 others seize the opportunity in captivity. Black widow spiders are the most common spider killer, and about half of spider deaths are caused by widow spiders; this group includes the infamous hourglass black widow, as well as close relatives such as the African button spider. These spiders are small, up to 0.4 inches (1.1 centimeters) in size, and their targets are usually small, young snakes, but they have enough venom to kill larger animals.
Members of the tarantula family killed another 10% of the snakes. These larger spiders do not form webs, but are active in hunting prey on the ground or in trees. Another 8.5% of predation events are carried out by large circular woven spiders, which are also known for preying on bats and birds. These spiders can weave large, strong, round webs. Once the spiders kill the snake, they suck out their internal organs like insects.
This is the Brazilian forest where a tarantula captures a small spiny coral snake and brings it back to its burrow. Tarantulas do not weave webs, but hunt on the ground or trees.
Reports of spider-eating snakes come from all continents except Antarctica, although half of the reported incidents occurred in the United States and almost a third in Australia.
The researchers found evidence that spiders preyed on 86 different species of snakes, with snakes of the yellow snake family being the most common victim. Nefer and Gibbons write that this family includes common species such as the boom snake and the rat snake.
Most of the snakes attacked by spiders are small-weight juvenile snakes. But sometimes it bites large snakes: the largest can be up to 3.25 feet (100 centimeters) long and weigh several ounces, usually killed by round or large tarantulas. Black Widow can defeat a snake that weighs 30 times more than herself. One report said a spider wrapped around a 6-inch (15-centimeter) long garter snake that weighed 355 times as much as the Black Widow.
Spider venom can take hours to days to kill snakes, and 30 percent of them are poisonous in their own right. Of the reported spider attacks, 86 percent of snakes were fatal, while only 1.5 percent escaped on their own.