Enlarge / The colorful jumping spider Siler collingwoodi mimics the walk of an ant to evade predators. (credit: Hua Zeng)

We typically think of camouflage in nature in terms of bodily coloration, enabling the species to blend in with the background and evade predators. But previous studies have documented locomotor mimicry in some species, like swallowtail butterflies and clearwing moths, as well as the jumping spider Myrmarachne formicaria, which mimics the limb use and general movement of ants. The latter is an example of perfect mimicry, generally assumed to be most effective in terms of evading predators.

But Hua Zeng, an ecologist at Peking University in China, and colleagues were intrigued by the colorful jumping spider Siler collingwoodi , which exhibits imperfect mimicry, and decided to run some lab experiments to determine how this might confer protective benefits They also set out to explore the effectiveness of the spider's coloration as a camouflage strategy, describing their results in a new paper published in the journal iScience.

“Unlike typical ant-mimicking spiders that mimic the brown or black body color of ants, S. collingwoodi has brilliant body coloration,” said Zeng . “From a human’s perspective, it seems to blend well with plants in its environment, but we wanted to test whether their body coloration served as camouflage to protect against predators.”

Enlarge (credit: Robert Llewellyn / Getty Images)

Black widows must despise Clint Sergi. While working on his Ph.D. in biology at the University of Wisconsin-Milwaukee, Sergi spent his time designing little challenges for spiders—which often involved rewarding them with tasty dead crickets or confounding them by stealing the crickets away. “The big question that motivated the work was just wanting to know what is going on inside the minds of animals,” he says.

Biologists already know spider brains aren’t like human brains. Their sensory world is geared for life in webs and dark corners. “Humans are very visual animals,” says Sergi. “These web-building spiders have almost no vision. They have eyes, but they're mostly good for sensing light and motion.” Instead, he says, a black widow’s perception comes mainly from vibrations, kind of like hearing. “Their legs are sort of like ears that pick up the vibrations through the web.”

Enlarge / This little guy looks too perky to need a nap. (credit: Tony Liu )

Our sleep is marked by cycles of distinct brain activity. The most well-known of these is probably rapid eye movement, or REM sleep, which is characterized by loss of muscle control leading to twitching and paralysis, along with its eponymous eye movements. REM sleep is widespread in vertebrates, appearing in many mammals and birds; similar periods have also been observed in lizards.

Figuring out what might be going on beyond vertebrates can get a bit challenging, however, as identifying what constitutes sleep isn't always clear, and many animals don't have eyes that move in the same way as those of vertebrates. (Flies, for example, must move their entire head to reorient their eyes.) But an international team of researchers identified a group of jumping spiders that can reorient internal portions of their eyes during what appears to be sleep.

And according to this team, the spiders experience all the hallmarks of REM sleep, with periods of rapid eye movements associated with muscle twitching.

(credit: Preston Innovation Laboratory)

Shortly after the Preston Innovation Lab was set up at Rice University, graduate student Faye Yap was rearranging a few things when she noticed a dead curled-up spider in the hallway. Curious about why spiders curl up when they die, she did a quick search to find the answer. And that answer—essentially, internal hydraulics—led to delightfully morbid inspiration: Why not use the bodies of dead spiders as tiny air-powered grippers for picking up and maneuvering tiny electronic parts?

Yap and her colleagues—including adviser Daniel Preston—did just that. They transformed a dead wolf spider into a gripping tool with just a single assembly step—essentially launching a novel new research area they have cheekily dubbed "necrobotics." They outlined the process in detail in a new paper published in the journal Advanced Science. The authors suggest the gripper could be ideal for delicate "pick-and-place" repetitive tasks and could possibly be used one day in the assembly of microelectronics.

Preston's lab specializes in so-called soft robotics, which eschews the usual hard plastics, metals, and electronics in favor of more nontraditional materials. Hydrogels and elastomers, for example, can serve as actuators powered by chemical reactions, pneumatics, or even light. Roboticists have also long found inspiration for their designs in nature, studying the locomotion of such animals as cheetahs, snakes, insects , starfish, jellyfish, and octopuses. (See, for example, our story on the development of the OctaGlove, designed to grip slippery objects underwater.)

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