The latest addition to the “animals that produce unexpected noises” list is the European spiny lobster (Palinurus elephas). Found in decreasing numbers across European waters, these lobsters get their name from the numerous sharp spines on the hard upper shell (carapace), abdomen, and other larger appendages. But it is the rubbing together of two parts of their long antennae that produces their fart-like sounds.
French and US researchers recorded 1,560 of these so-called “antennal rasps” by 24 lobsters in the Bay of Saint Anne du Portzic, France. They found that size certainly did matter when it came to the sound given off. Using underwater microphones, the team registered the rasps of larger individuals at around 100 meters (328 feet), but the smallest lobsters were only heard as far as 10 meters (33 feet) away. The team predicts that with low background noise, the rasps of the big 2-kilogram (4.4-pound) lobsters could be detected up to 3 kilometers (1.9 miles) away.
“To date, the scientific literature has shown that spiny lobsters mainly produce these sounds to startle predators, such as octopuses and fish,” Youenn Jézéquel, a Marine Biology PhD candidate at the University of Western Brittany (UBO), France, told IFLScience. “However, we still do not know if they can use these sounds as a means of intraspecific communication between conspecifics.”
Jézéquel is the lead author of the study, published in Nature’s Scientific Reports, documenting the acoustic chirps of the lobsters. But they are not the only species to use their antennae to produce noises. “Interestingly, the closest animals presenting this kind of sound-producing apparatus do not live underwater but live on land, and are called insects,” Jézéquel said. “Spiny lobsters are notably closely related to crickets, which has bought their nicknames by fishermen as 'sea crickets'.”
Historically, however, this fondness for “sea crickets” has led to the overfishing of the species and accounts for its current “vulnerable” status on the IUCN Red List. Jézéquel hopes that his and his colleagues work could lead to non-invasive acoustic monitoring of the European spiny lobsters to help aid conservation efforts.
“Most conservation efforts have used highly invasive and destructive trammel nets to estimate their population densities and distributions underwater,” Jézéquel explained.
“Passive acoustics seem very promising because it simply aims to listen, using hydrophones (that are similar to microphones in air), to sounds produced by marine animals to obtain critical information. For example, it can help to localize individuals, estimate population densities or study activity patterns in an ecosystem.”
Although employed for other marine mammal and fish conservation, not enough has been known about the propagation of spiny lobster’s sound underwater to make acoustic monitoring possible. The team’s estimation of detection distances in the shallow coastal regions, where their work took place, is “only the beginning in this wide and new area of research,” Jézéquel said.