Understanding Sound Production and Hearing in Clawed Lobsters, Homarus Americanus and Homarus Gammarus Ver Wonder What Lobsters Hear
Understanding sound production and hearing in clawed lobsters, Homarus americanus and Homarus gammarus ver wonder what lobsters hear,
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WheelSSeaweedehaewe elWatch dW hharvesta • 16 A Comp at ass Pub rvcehs t• 22 lication • $$2.75 May scallopaandCnadLittlep lobsterloeb fleetCs Rivert bait: • launches18 A 2.75 oedrd beari Bt:o A anotherttaleale oofsft tthreeihl ljumbor geet speciestin Osmondg it adto Cnoe. Boats Reborne sp e• c32ies Perseverance: a new life NeWWheelwhNew Beeola WatchBoats • • 24 30 SSuperiorTwoup fresh Marinefor springOff Wat sclassicCoursea Products:•launchest c3h0 •,Novi 3 06• , 3237 erior MaSrixin sep Pring launches Miss Marienarod u&c tMaria:s: nnewew oownerwnership; COCOMMMME A Crowleyhit 28ship; reborn And in 2000, I wrote in this space about COMMRCIALERCIAERC FISHERIL the w The Mystery of Lobster IALFISHERIES FISHEES N ate RIESEWNEW NEWS • r pprovenroveS n• S J UNE •rrecipe JUNEe 2020 • JUciNE2p0 192021e1 • 1 • 1 Vibrations (CFN May). The lobster sends the buzz by contracting Finally, we have some provocative answers – thanks to Dr. muscles in the head region. The sound signal vibrates the Youenn Jézéquel and a team of scientists from around the lobster’s entire body sending particle waves through the water. world. Lobsters hear these sounds by listening with hairfan organs If you’re a lobsterman or lobster field biologist you’ve no located in tiny, shallow pit-like depressions from end to end of doubt handled a lobster that vibrated or “buzzed” in your hand. the entire body. Way different, obviously from we humans, who To us, the lobster’s low frequency noise feels like a vibrating talk with localized mouths and hear with ears. cellphone and sounds like a buzz. Another big difference between our hearing and that of a Have you ever wondered if other lobsters hear the buzz? lobster is the type of sound signal we hear. The answer is yes. We – like other mammals including whales and dolphins – Have you ever wondered how lobsters hear? are sensitive to pressure waves; while lobsters – like fish and The answer is hairfans. No kidding. invertebrates – decode particle motion. Instead of localized ear organs, lobsters hear using cuticular Lobsters making and hearing noises may seem like stating “hairfans” prevalent along the entire length of their bodies. the obvious, but it’s not. Although the shell itself is made up of dead tissues, sensory How lobsters hear and why lobsters produce sound was hairs stick out of the tiny holes in the lobster exoskeleton. previously unknown. Receptors at the base of hair-fan organs sense stimuli – Previous attempts to characterize lobster sounds in including particle motion that lobsters detect as low frequency laboratory tanks failed, partly because of the way sound sound. attenuates (bounces off the walls). New understanding and use Here’s how sending and receiving the buzz sound signal of new ways to record sound underwater provides solutions to works in American lobster. (Spiny lobster do some things how the size and shape of the container presented obstacles to differently). data accuracy. Once sounds could be properly characterized and recorded, Jézéquel staged lobster boxing matches Fig. 1. A drawing of to ascertain how sounds might be used in the dissected anterior agonistic encounters. cephalo-thoracic region Buzzing was recorded – most notably when of the lobster (Homarus See LOBSTER DOC, next page Americanus). This type of preparation was used in all experiments. For this drawing the statocyst is exposed in the basal segment of the right antennule. The nerve seen coursing from the brain to the statocyst is the combined statocyst and antennular nerve. Credit: Cohen 1955.
Fig. 2. Drawing of the right statocyst as seen from above. The dorsal region of the basal antennular segment and the dorsal statocyst wall have been removed, thereby exposing the lumen contents. Anterior is toward the top, lateral is to the right. Note the crescentic sensory cushion with its four hair rows. The statolith mass is seen in contact with the inner three rows. The fine medial thread hairs project horizontally into the lumen from the posterior region of the medial wall. The large antero-lateral hairs are visible and the opening into the cyst can be discerned at the antero-medial boundary between the cyst and antennular chitin. Credit: Cohen 1955.
COMMERCIAL FISHERIES NEWS • JUNE 2021 • 1 that marine mammals and fish are Lob Doc impacted by anthropogenic noise, impacts on marine invertebrates, Continued from previous page including lobsters, are not yet one of the two males managed to established. establish dominance. In such a case, Considering what we know the dominant male buzzed after the now: that lobsters detect sounds subordinate lobster conceded the in the same frequency band as fight. Perhaps he is saying touché? anthropogenic noise (i.e. low Finding out that lobsters do frequencies), we are able to target indeed hear the buzzes of other clear concerns and crucial needs to lobsters and learning that the understand and assess the impacts receptors for hearing the buzz of underwater man-made noise on involve hairfans is big news, frankly. the economically and ecologically Demonstrating that lobsters important lobster. also buzz in social context by l Read about lobster sound appearing to use acoustic signals detection and find more references to communicate during the boxing WHOI photos at: match is extraordinary. This makes https://journals.biologists.com/jeb/ me wonder what else lobsters are article/224/6/jeb240747/237913/ buzzing about. Sound-detection-by-the-American- In addition to being just lobster-Homarus plain interesting, the basic l Read more about particle motion research conducted by the lobster and underwater acoustic ecology at: bioacoustians brings timely news for https://besjournals.onlinelibrary. the lobster industry. wiley.com/doi/10.1111/2041- Now that we know lobsters use 210X.12544 acoustic signals to talk to each other, Diane Cowan, PhD, is executive it’s time to find out what they are director and senior scientist, The saying. Lobster Conservancy,
Credit: Laverack 1962. Fig. 3. Illustration of hairfan organ, basically a shallow pit-like depression with hairs sticking out and nerve fibers running in; not sure exactly sure what receptors inside look like or how they work. A piece of the cuticle is shown as a shallow depression in which the hairfan is situated. The base of the organ is innervated, the nerve fibers passing from the peripheral nervous system through a small pore in the cuticle. WHOI photo
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