As the researchers observed how the spiders reacted, they noted that the animals responded to the different point-light displays by pivoting and facing them directly, which indicated that the spiders were able to recognize biological motion. Curiously, the team found that the spiders preferred rotating toward the random display when it was part of the choice. The researchers initially thought they would turn more toward the displays simulating another spider and possible danger, but the behavior made sense in the context of jumping spiders and how their secondary sets of eyes work to decode information.

“The secondary eyes are looking at this point-light display of biological motion and they can already understand it, whereas the other random motion is weird and they don’t understand what’s there,” De Agrò said.

The scientists hope to examine biological motion recognition in other invertebrates, including mollusks. The research could lead to greater understanding of how these creatures perceive the world, De Agrò said.