Not all heroes wear capes, but these termites did for science
The researchers started by collecting simple-looking termites from the wild. They then taped pieces of paper to their backs, which looked more or less like capes: solid black, solid white, or black and white striped.
This wasn’t the last attempt to introduce minor heroes to the Marvel Cinematic Universe. It was an attempt to learn something about how jumping spiders, some of nature’s most common and smart predators, sense their prey.
In nature, most prey avoid being spotted by predators by blending in with their surroundings. But some species strive to stand out. For example, monarch butterflies, yellow jacket wasps and ruby velvet ants use bright or contrasting colors to warn predators of their toxicity.
Scientists are still trying to decipher which predators observe such displays. In particular, little is known about how jumping spiders process these color patterns. According to Lisa Taylor, a behavioral ecologist at the University of Florida, they have sharp vision thanks to a set of large, forward-facing eyes.
To determine how two species of jumping spiders respond to vivid warning signals, Dr. Taylor and her colleagues hatched termites in capes suitable for scientific cosplay and placed them in a petri dish with the eagle-eyed arachnids. Their findings were published in the journal on Wednesday Royal Society Open Sciencereveal that although the spiders quickly spotted the termites in the striped capes, they rarely attacked the striped termites, providing an explanation for why numerous other species use conspicuous stripes to deter predators.
Most previous research into how predators perceive aposematic or strikingly colorful displays has focused on carnivorous birds. But most species with such patterns are small insects. This means they likely evolved their visual defenses in response to arthropod predators, such as arachnids.
That’s where jumping spiders come into the picture. With more than 6,500 species found worldwide, jumping spiders are voracious arachnids that feed on virtually any invertebrate they encounter. They also have various visual capabilities. Although most species have good vision, some species can see colors, including those commonly used in visual defense, such as red and orange.
Dr. Taylor and her team studied two species of jumping spiders common in Florida: the royal jumping spider, or Phidippus regius, and Habronattus trimaculatus. While P. regius sees only two colors, H. trimaculatus sees three. P. regius also has stronger immunity against prey toxins, creating H. trimaculatus potentially more wary of attacking brightly colored prey.
The researchers placed two termites from each cape variety in a petri dish with a jumping spider and recorded which termite the spiders looked at and which one they ultimately attacked.
They discovered that P. regius routinely spotted termites with striped and solid black capes first. However, the spiders attacked termites in striped capes much less than those wearing black or white. H. trimaculatus also showed a tendency to spot termites in striped capes first. But these spiders ultimately turned out to be much more picky, attacking termites about half as often as P. regius.
The new findings suggest that many jumping spiders are inherently able to locate striped patterns. In previous studies, Dr. Taylor that another species of jumping spiders was more likely to spot termites with striped patterns than those with yellow or gray colors. Another species attacked termites in striped capes less often than those wearing gray capes.
“Stripes always mean something,” said Dr. Taylor. “They draw attention or reduce the attack, or do both.”
This may illustrate the effectiveness of stripes in attracting a predator’s attention.
“Stripes enhance internal contrast,” says Tom Sherratt, an evolutionary ecologist at Carleton University in Ottawa who studies how flies mimic wasps’ black-and-yellow patterns to deter predators, but was not involved in the current paper . “Sometimes having a single color, such as yellow or red, is not enough to increase your conspicuousness; you need contrast.”
Dr. Taylor thinks the ability of distinctive stripes to both attract attention and deter attacks is why this pattern is so common in nature. “If most jumping spiders are looking for stripes, that’s a pretty good strategy because jumping spiders are everywhere,” she said. Several insect species with striped color overlap with the jumping spiders in the paper, including monarch caterpillars, treehopper nymphs and cucumber beetles. When it’s time to avoid being eaten, stripes are always in fashion.