Oh! Snap!: "Have You Heard Those Snapping Shrimp?" Redux : A Lowcountry Tail

This post is based on an oldie-but-goodie website article originally authored by Dennis Adams, Information Services Coordinator (Retired) for the Library's previous website. My husband and I live along a tidal creek and during the COVID-19 shutdown, we spent more time than usual enjoying the fragrances of the lowcountry while sitting on the porches in the early morning or early evening hours. Less traffic on the roads meant less traffic noise wafting over the salt marshes and more sounds of nature coming from the tidal creeks, including pops that we hadn't noticed in a long time. Perhaps you heard some too. Latest update: 24 March 2025

You may have wondered what causes those popping noises coming from the marshes and pluff mud at low tide.

Is it the mud popping? Or maybe a creature like an oyster or a clam?

The answer is: "None of the above."

You've heard of snapping turtles, but how about "snapping shrimp"? In an e-mail [to Adams in or before 2007], Amber Von Harten, [then Fisheries Specialist at the SC Sea Grant Extension Program explained] that the marsh popping sound "is made by a small crustacean that makes its home in the salt marsh, called the Bigclaw Snapping Shrimp, Alpheus heterochaelis.  The shrimp grows up to two inches in length and is characterized by its single, large, modified claw used to generate the loud popping sound many residents hear emanating from the marsh at low tide."

She continued: "Basically the fingers of the claw have two opposing smooth disks with a thin layer of water in between the disks. When the disks separate due to increased pressure, the claw forcibly opens and makes the loud popping sound. This concussion, produced by the claws separating, stuns small animals and is a manner in which to capture prey. The sound is also a defense mechanism to ward off larger predators."

Von Harten found her information in Seashore Animals of the Southeast: A Guide to Common Shallow-Water Invertebrates of the Southeastern Atlantic Coast by Edward E. Ruppert and Richard S. Fox (Columbia, SC: University of South Carolina Press, 1988). She highly recommends this book to local residents as "one of the best for our region of the coast."

Bigclaw Snapping Shrimp are also known as "pistol shrimp." According to Seashore Animals of the Southeast, their sound "can be heard clearly across a large room" in aquariums and "reportedly can break glass." (Some members of the saltwater aquarium community affirm that this is possible while others believe this statement to be more along the lines of an urban legend.) The shrimp's larger claw has a notch "in both the upper and lower margins at the base of the fingers."

Figure 5.1: (A) Alpheus heterochaelis - one of  the largest snapping shrimp. The large snapper claw may be either on the right or the left in both sexes. Modified after Brooks & Herrick [8]. (B) Close-up of the snapper claw in its cocked position. The claw is made transparent by the use of methyl salicylate. The claw has a protruding plunger (labeled pl ) on the dactyl ( d ) and a matching socket ( s ) in the immobile propus ( p ) (Photograph by B. Seibel). During the extremely rapid closure of the snapper claw a high-velocity water jet is formed when the plunger displaces the water from the propus socket. 

Though the web article "Snapping Shrimp Make a Flash with Bubbles" (October 10, 2001) from the California Academy of Sciences' "This Week in the Wild" website is no longer active, the three videos below confirm the statements: "The water jets out of the claws at a speed of up to 62 miles per hours, producing the "low pressure bubble(s) that collapse with a telltale crack." If enough shrimp are snapping their claws at a given moment, they can interfere with sonar tracking of submarines in their immediate area!

"Amazing Pistol Shrimp Stun 'Gun'" from Nat Geo Wild's "World's Deadliest" series:

"Listen to the Crackling of Snapping Shrimp" from Woods Hole Oceanographic Institution: 

Among the comments was this one : "It sounds like they are being fried" with which I concur. This is closer to the sound that I hear behind my home.

"Pistol Shrimp Sonic Weapon" from BBC Weird Science:

I'm a little skeptical about whether the pistol shrimp sounds as much like a pistol firing as the video seems to indicate - but this video does not give the species name of the shrimp being recorded. It may be that the cavitation bubble imploding sound recorded here is not one made by Alpheus heterochaelis that lives in our local salt marshes. 

When the shrimp snap their claws, they also produce a visible but extremely brief (10 nanoseconds or less) burst of light. Nobody knows whether the light serves any purpose for the shrimp. Heat inside the tiny bubbles after a snap can reach 8,500 degrees Fahrenheit. 

Alpheus heterochaelis  Photo by Robert Aguilar, Smithsonian Environmental Research Center. 

The Smithsonian Marine Station at Fort Pierce, Florida website says that these living noisemakers [search term "Bigclaw snapping shrimp"] range from the southern Chesapeake Bay to Florida, extending further south to the Gulf of Mexico, Cuba, and Brazil. It is a colorful creature: the body color of the Bigclaw Snapping Shrimp is translucent green, and its walking legs are pale red. Often there are bright red or orange tones on the tips of the claws and a blue or purple edge along the uropods (fantail) and body. 

Sources:

"What is a Salt Marsh?" in Guide to the Salt Marshes and Tidal Creeks of the Southeastern United States by the SC Sea Grant Consortium  

Seashore Animals of the Southeast: A Guide to Common Shallow-Water Invertebrates of the Southeastern Atlantic Coast by Edward E. Ruppert and Richard S. Fox (Columbia, SC: University of South Carolina Press, 1988).

Nonideal Turbulence - Scientific Figure 5.1(A) and (B) on ResearchGate 

Amazing Pistol Shrimp Stun 'Gun'" from Nat Geo Wild's "World's Deadliest" series, 11 April 2013 (01:12)

"Listen to the Crackling of Snapping Shrimp" from Woods Hole Oceanographic Institution, 17 February 2020 (01:13) 

"Pistol Shrimp Sonic Weapon" from BBC Weird Science, 16 January 2009 (01:36) 

Wikipedia contributors, "Cavitation," Wikipedia,  

Alpheus heterochaelis, photo by Robert Aguilar, Smithsonian Environmental Research Center, 13 April 2006 posted to Wikipedia Commons on 25 February 2019 

"Alpheus Heterochaelis" by J. Masterson, last updated 1 September 2008, Smithsonian Marine Station at Fort Pierce website 

Love is in the Air - Lovebugs, that is! : A Lowcountry Tail

Note: Dennis Adams, former Information Services Coordinator, now retired, wrote the following article about the Lowcountry's favorite(?) insect. (At least it doesn't bite - which is more than I can say about most lowcountry insects.) The article was on the Beaufort County Library's website for many years until the Library switched to Wix software in 2016. Dennis last updated the article in 2007. (My! how time files - poor pun intended.) I am reposting the article with only minor edits and additions which are shown below in italics - but I do not claim credit for the scientific names and book titles show in italics below. Those are typically printed in italics. Latest update: 24 March 2025 - gmc

Lovebugs by Dennis Adams, 2007: 

Clouds of "lovebugs" swarm over Beaufort - and other parts of the lowcountry - in April and May and mid-September to October each year. Dr. Timothy A. Mousseau of the University of South Carolina says that "many people don't realize that these flies are actually invaders from Central America and have been working their way northward along the coast." The invasion began around 1920, and winds first carried the insects to Louisiana. Further, there is no truth in reports that lovebugs were introduced to the United States by misguided insect researchers.

Lovebugs are now found from Costa Rica, Guatemala, Honduras and Mexico to South Carolina, Georgia, Florida, Alabama, Louisiana, Mississippi and Texas. These black flies have a red thorax. They are not true "bugs," despite the "lovebug" nickname. The BugGuide website classifies the insects this way:

Kingdom Animalia (Animals)

   Phylum Arthropoda (Arthropods)

      Subphylum Hexapoda (Hexapods)

          Class Insecta (Insects)

              Order Diptera (Flies)

                  No Taxon ("Nematocera" (Non-Brachycera))

                        Infraorder Bibionomorpha (Gnats, Gall Midges, and March Flies)

                               Family Bibionidae (March Flies)

                                      Genus Plecia (Lovebugs)

The scientific name is Plecia nearctica, of the same Order Diptera as house flies and mosquitoes, so the insect's other nickname - "honeymoon fly" - is more apt. Though scientists have identified more than 200 species in the genus Plecia, only two species fly around the United States. Plecia americana is the second species, ranging from North Carolina to Mexico and appearing only in April, May and June. This woodland insect stays away from highways.

You can see images of Plecia americana and Plecia nearctica on the BugGuide website. 

According to Simon and Schuster's Guide to Insects, the mowed grass rotting along interstate highways have been the ideal breeding ground for lovebugs. The larvae also develop under cow manure. Generous rainfall and mild winter temperatures increase the numbers of lovebugs. Rains from September 1999's Hurricane Floyd accounted for a bumper crop of these "honeymoon flies" in the South Carolina Lowcountry. So with fewer owners now burning off their woodland properties each year and more cattle in bigger and better pastures, numbers of lovebugs are sure to grow.

Wikipedia https://en.wikipedia.org/wiki/Lovebug

It should come as no surprise that the nickname comes from the lovebugs' habit of mating while coupled in midair. The males' eyes are four times larger than the females', the better to spot a mate in a swarm. Up to eight males may compete for a single female. Females are the larger partner and live for only 72-86 hours, the males last nearly 92 hours. Pairs stay coupled for about 56 hours with successful fertilization taking about 12 1/2 hours, though larger male rivals may disrupt and separate the couples. Mating lovebugs do not appear to uncouple in flight or at night, and will continue to feed on nectar or pollen during their couplings. The male transfers not only sperm but also protein and sugar to nourish the female and her 152 to 600 eggs. "The male is an empty shell afterwards," said Mousseau.

Lovebugs vary in size by gender with males being the smaller. Males grow to about 1/4 inch while females tend to be around 1/3 inch in length.

Lovebugs may reach a height of 1500 feet in flight. It is apparently the larger female who does the flying for the couple. Each generation cycle lasts about four weeks.

Though lovebugs do not sting, bite, or carry disease, they do spatter thousands of auto windshields and clog countless radiators. The University of Florida's "Living with Lovebugs" by Norman C. Leppla terms them a "nuisance past, as opposed to destructive or dangerous." 

"They are drawn to vehicle vibrations and fuel vapors exposed to sunlight," wrote Bradenton (Florida) Herald reporter Brian Neill, "and they prefer diesel fuel over regular gasoline." Mousseau doubted that fuel vapor attracts lovebugs, however. He believed that lawn mowers stir up lovebugs that are hiding in the grass and vehicles hit insects that are on their way to lay eggs along the damp roadsides. Leppla confirmed that lovebugs are attracted to certain essential oils and chemical compounds, including one emitted from automobile exhaust systems that are quite similar to those emitted from decaying organic matter so enticing to an egg-bearing female lovebug. Heat from auto engines may also attract lovebugs. Leppla sums it up this way: "Lovebugs apparently accumulate in relatively warm, humid, sunny areas with food and chemicals in the atmostphere that mimic oviposition sites."

Clemson Cooperative Extension offers some practical advice regarding minimizing lovebug splatter in its Factsheet: Avoid driving during their active period -- which is 10 AM to dusk; By driving slower, the lovebugs might be able to fly out of the way of your vehicle; and Consider a grill or hood cover to prevent clogging up your car radiator or damaging your paint finish. 

Decaying lovebugs release a mild acid that can etch auto paint surfaces, especially when bacteria is left to interact with the "gunk." Leppla states that lovebug viscera is not permanently damaging unless it is left to bake in the sun for more than 24 - 48 hours. The best remedy is to use a car wax on a regular basis, soak the car surface with water and apply 15 to 20 minutes of "elbow grease," and remove the lovebugs spatter within 24 hours. The maligned lovebugs also play a helpful role: their larvae help to recycle decaying organic matter.

Hungry birds are the lovebugs' natural enemies, along with some spiders and dragonflies, but the insects are hard to control. Chemicals dropped by airplanes in the late 1960s killed few bugs and cleared the highways for only a half hour. Though a type of fungus has killed up to one third of larvae in a more recent test, researchers are far from any real solution to the lovebug problem. And because the lovebugs are classified as nuisances rather than dangerous, there is not much incentive to apply limited scientific research funds to the insect. Leppla says that "it is best just to avoid lovebugs if they become a nuisance during their brief appearances each year."

And pity poor Florida! In addition to the big "plagues" in the spring and fall, small numbers of lovebugs have been spotted there every month except November. A bumper crop occurred in 2019 due to warm weather from October to April. 

Sources:

"Living with Lovebugs" by Norman C. Leppla, UF/IFAS Extension, University of Florida, latest review December 2018.

"Love Bugs Love Wetter Weather" by Lynne Langley, Charleston Post and Courier (Charleston, SC), 24 September 1999, pp. 1-A, 19-A.

"Lovebugs Factsheet," by Eric P. Benson, Amy L. Kilpatrick and patricia A. Zungoli, HGIC 2432, 2 August 2004, accessed 15 May 2019.

Simon and Schuster's Guide to Insects by Ross H. Arnett and Richard L. Jacques, New York: Simon and Schuster, 2981.

The University of Florida and the Florida Department of Agriculture and Consumer Services maintain an in-depth page about lovebugs.

"Warm, Wet Weather May Bring Epic Lovebug Season" by Jan Wesner Childs, 7 May 2019, Weather Channel website, Accessed 15 May 2019.