The behavior, documented among male bigfin reef squid in Indonesia and Egypt, is described this month in the journal Ecology.
Museum scientist and study co-author Samantha Cheng thinks that this "probing behavior" could be a type of mate-guarding, a mating strategy in which males attempt to prevent a mate’s eggs from becoming fertilized by a rival.
Investigating nesting sites in advance, for example, may allow males to ensure the area is free from sneaker males, a term for “smaller males masquerading their patterning to look a little more like a female," Cheng said. This female patterning allows sneaker males to fly under the radar of dominant males.
Bigfin reef squids are common in tropical oceans and the Mediterranean. But this vast geographic range can make studying them challenging. "It's really hard for just a couple of researchers to try to understand what's going on," said Cheng. "The only way we can do that is by working together."
Eduardo Sampaio of the University of Lisbon in Portugal, who is lead author of the study, first observed the probing behavior in Egypt in 2019. After he described it on Twitter, Cheng realized she had seen it in Indonesia in 2013. Observing the same behavior at sites that are more than 6,000 miles apart indicates that it may be widespread in bigfin reef squids.
Ultimately, this research can help inform biodiversity and conservation efforts. "We fish the squid, we eat it—it's not like this is a never-before-seen species that we've never encountered before,” said Cheng. “But given all of that, we're still discovering something new, which just goes to show how much we have yet to learn about marine ecosystems."