Mating squid don’t stop for loud noises

Loud hammering noises like pile driving disrupt the mating behavior of longfin squid, but the cephalopods seem to get acclimated to the incessant noise, according to new research.

Hammering piles into the seafloor is a common technique used for building offshore structures like wind farms, but previous research shows the high-intensity noise can damage marine animals’ tissues when they are nearby or alter their behavior when the animals are further away.

This video shows an experiment conducted at Woods Hole Oceanographic Institution testing the effect of pile driving noise on mating longfin squid. The results show some longfin squid get startled when they first hear pile driving noises during mating, but the animals seem to ignore the din as time goes on, returning to their normal coupling activities after some time.

In this experiment, researchers exposed groups of mating squid to pile driving noise within their lab. They placed a large male, a small male, and a female squid into a cylindrical tank and added an egg mop – a cluster of laid eggs – to entice the animals to perform mating-related behaviors.

After one of the males started consistently guarding the female, the researchers exposed the animals to 5-minute playbacks of pile driving noise. They repeated the process twice, with 10-minute breaks in between each playback, on dozens of groups of mating squid. With a speaker on one end of the tank and a hydrophone (an underwater microphone) on the other, the researchers measured noise levels in each tank and observed how the animals responded as a group.

The researchers saw some squid showed alarm on the first pulse of the first playback but became habituated to the racket the longer it went on. After these squid startled when the noise began, the males went back to mate guarding usually within seconds. Many individual animals showed no sign of alarm at all.

Interestingly, the squid in these experiments behaved differently from individual squid in previous experiments. In prior research on individual animals, squid showed considerable alarm when startled with pile driving noise – they exhibited antipredation behaviors like inking, jetting, or changing color.

But the squid in these experiments quickly acclimated to the disruption – possibly because mating is crucial to their survival, according to the researchers.

Read more about this research here:
https://blogs.agu.org/geospace..../2020/02/18/mating-s

Footage copyright Woods Hole Oceanographic Institution.