WOODS HOLE, Mass. — A new study indicates that lobsters can possibly hear through their hair.
The study by researchers at the Woods Hole Oceanographic Institution in Massachusetts shows that lobsters can detect low-frequency sound and indicates that anthropogenic noise could affect the crustaceans.
The scientists found that hairfans, the external cuticular hairs that cover much of a lobster’s body, are likely responsible for sound detection and imply that hearing is “mechanistically possible in a wider array of marine invertebrates than previously considered,” according to the WHOI.
“We found that the lobsters’ frequency of sound detection overlaps the frequency of the buzzing sounds that they produce,” Youenn Jézéquel, a postdoctoral researcher at WHOI and the lead author of the paper, said in a statement. “This means that lobsters are clearly capable of communicating with these buzzing sounds while engaged in important behavior such as during aggressive encounters between males, which are crucial confrontations during reproduction.”
This is the first study that demonstrates sound detection in the American lobster, using what’s known as auditory evoked potential methods. Scientists placed electrodes near the brain of the lobster to detect neuron responses to sound.
To determine which sensory organ is responsible for sound detection, researchers looked at several different possibilities. Besides hairfans, they also investigated statocysts, which are located at the basal segment of each antenna in the lobster’s head.
Those were ruled out because researchers found no significant differences in sound detection with or without antennas, but they did see that lobsters with immobilized hairfans had a lower auditory evoked potential response.
The study was done at WHOI last year with 16 adult lobsters. They were in an opaque plastic tank and the noise was funneled in with a small underwater speaker played at different frequencies.
Lobsters produce a buzzing sound through the rapid contraction of internal muscles located at the base of their second antenna, which causes their carapaces to vibrate. But it was previously unclear if they could hear because crustaceans lack air-filled spaces and compressible tissues required for sound pressure detection. They do possess several external and internal sensory receptors that have been shown to detect low-frequency particle motion.
At a time when officials are considering building offshore wind turbines in New England, Jézéquel said this finding raises concerns about the potential of noise on the lobsters.
“This study is a preliminary step to understanding the impact of anthropogenic noise on lobster behavior,” he said. “We need marine renewable energy, but we don’t want to impact marine life. It’s very important to assess the impact of pile driving noise on lobster populations to be able to tell fishermen, politicians and others about these impacts and to try to reduce sounds produced by offshore wind farms as much as we can.”
Pile driving is a major concern because of the high intensity of sound that it releases underwater. In the future, Jézéquel wants to expose lobsters to different noises, including shipping and pile driving.
Scientists have known that marine mammals and fish use sounds to communicate, but there is much less data on sound detection in aquatic invertebrates, according to WHOI.
“What we all hope to discover is that anthropogenic noise would not have much impact on the life cycle of lobsters,” Jézéquel said. “However, we are not sure yet, considering the impact that has been shown on marine mammals and fish.”