Animals

Fingers crossed for finding nothing: July marks the main trapping season to check for Asian giant hornets still infesting Washington state.

The first of these invasive hornets found in North America in 2021, in June, was probably not from a nest made this year, scientists say. So that find doesn’t say how well, or if, the pests might have survived the winter. Yet that hornet shows quite well the relentless risk of newly arriving insects.

That initial specimen, a “crispy” dead male insect lying on a lawn in Marysville, Wash., belongs to the hefty species Vespa mandarinia. Nicknamed murder hornets, these were detected flying loose in Canada for the first time in 2019 and in the United States in 2020 (SN: 5/29/20). Yet the “dry, crispy” male is not part of known hornet invasions, said entomologist Sven Spichiger at a news conference on June 16.

Testing shows the male “is definitely not the same genetic line as the ones we have found,” said Spichiger, of the Washington State Department of Agriculture in Olympia. Neither the U.S. finds, until now all from Washington’s Whatcom County, nor British Columbia’s on the other side of the border are closely related to the newfound hornet. It’s a separate incursion no one had noticed until now.

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This oddball new specimen may help correct the skewed impression that sneaky invasive arrivals are rare. The hornets’ appearance in North America may have been a shock to some, but in reality, worrisome insects show up often, and will probably keep doing so. Fortunately making a permanent home is harder than getting here, scientists say.

When news of the Asian giant hornets’ arrival first broke in 2019, one of the people who was not at all surprised at a foreign species was entomologist Doug Yanega of the University of California, Riverside. “It is very fair to say that there are many invasive species,” he emphasizes. “We just got a new African mantis species in California this past year in LA, and the expectation is that it is likely to spread.”

But even alarming pest arrivals rarely kick up the fuss prompted by Asian giant hornets. At a peak in hornet news during May 2020, Yanega contrasted the new intruders with the South American palm weevil (Rhynchophorus palmarum). That big weevil had reached southern California and could “wipe out every palm tree in the state,” according to Yanega. Yet, “there have been ZERO [national] mainstream media reports about this, an insect that seriously threatens to have a VASTLY greater negative impact on the economy and our way of life than those hornets ever will,” he fumed in an e-mail.

That relentless influx of invading insects may be one reason so few make it into the general news. For instance, U.S. Customs and Border Protection reported 31,785 incidents detecting some pest just for fiscal year 2020.

For 2021, to pick just one example of worrisome arrivals that have not gone viral, inspectors at Washington Dulles International Airport in Virginia and later at Baltimore/Washington International noticed little brown pests called Khapra beetles (Trogoderma granarium) in Basmati rice and then in dried cow peas that travelers were trying to bring in from abroad. Officials banned the contaminated foodstuffs.

The Dulles contraband had the bigger number of living insects: 12 larvae and four adults. Even that tiny number of tiny insects was unacceptable. This is the only insect species that U.S. customs officials act upon even when all specimens are found dead. The beetles nibble stored seeds but will also soil the goods with stray body parts and hairs that can make human babies fed dirty grain quite sick and adults uncomfortable. In 1953, a major California effort started to stamp out infestations of Khapra beetles and eventually preserved crop marketability. But the effort was expensive, costing the equivalent of about $90 million in today’s economy.

Tiny but destructive Khapra beetles (shown, side and front view), which California eliminated at great expense, almost got into the United States at least twice in 2021 in air passenger luggage. Customs stopped those two incursions.Both: Pest and Diseases Image Library, Bugwood.org (CC BY-NC 3.0 US)

Tiny but destructive Khapra beetles (shown, side and front view), which California eliminated at great expense, almost got into the United States at least twice in 2021 in air passenger luggage. Customs stopped those two incursions.Both: Pest and Diseases Image Library, Bugwood.org (CC BY-NC 3.0 US)

Beetles aside, menacing hornets of other species have shown up before the latest Asian giants, says Paul van Westendorp, an apiculture specialist who now strategizes British Columbia’s fight against V. mandarinia. In May 2019, just months before the discovery of an Asian giant hornet’s arrival, a V. soror hornet appeared in Canada. It was “alive, but not for long,” van Westendorp says. “I had a chance to admire that specimen.” Not a frail beast, this species hunts down other insects and has been reported to catch prey as large as a gecko. V. soror looks very much like a V. mandarinia, he says.

Even Asian giant hornets themselves have turned up at least once in the United States before 2020. An inspector in 2016 flagged a package coming into the San Francisco airport holding a papery insect nest but not mentioning insects on the label. The nest held Asian giant hornet larvae and pupae, some still alive when discovered. These and other species of hornets, including the ominously named V. bellicosa, accounted for about half of the 50 interceptions of hornets and yellow jackets flagged from 2010 to 2018 at U.S. ports of entry, researchers reported in 2020 in Insect Systematics and Diversity.  

Only some stowaways will manage to make permanent homes in new territory. Of these, the real troublemakers seem to be a minority. For instance, out of 455 plant-attacking insects that settled into forests in the continental United States, 62 cause noticeable damage, according to a 2011 tally from U.S. Forest Service researcher Juliann Aukema and colleagues. Even a few rampaging invasive pests, though, can get expensive. Biologists are throwing themselves into the fight.

Relentless as the onslaught of unwanted arrivals is, there’s hope for stamping out the more noticeable invasions if caught early. Vespa hornets are “very large-bodied and obvious, so people will see them,” says entomologist Lynn Kimsey of the University of California, Davis, one of the authors of the 2020 hornet overview. A Vespa affinis nest showed up in San Pedro, in Southern California at least a decade ago. However, she says, “it was killed and there’s been no sighting of the species since, as far as I’ve heard.”

Catching such intrusions early isn’t always easy, however. The port of Oakland takes in about 1 million shipping containers from overseas a year, but at best U.S. Department of Agriculture inspectors can check maybe only 10 percent for stowaway insects, Kimsey says. Add to this all the cargo coming into Long Beach, San Diego and the other West Coast ports — plus all the cargo jets. “What’s amazing is that we don’t see more invasives,” she says. “I think this tells you how hard it is for exotic species to get established.”

They’ll keep arriving though. All the more reason to keep an eye out for something funny on the lawn, even if it’s just a withered nugget. More

In an opening scene of the new film Fathom, Michelle Fournet sits at her computer in the dark, headphones on. The marine ecologist at Cornell University is listening to a humpback whale song, her fingers bobbing like a conductor’s to each otherworldly croak and whine. Software converts crooning whale sounds into the visual space of craggy valleys and tall peaks, offering a glimpse at a language millions of years in the making.

Debuting June 25 on Apple TV+, Fathom follows two scientific teams studying the enigmatic songs of humpbacks. The film captivates, diving into the quest to unveil the inner world of these animals and their ever-changing song culture — one considered far older than our ancestors’ first upright steps.

On opposite sides of the Pacific Ocean, scientists head out onto the water. In a mountain-fringed bay in Alaska, Fournet makes repeated attempts to talk to the whales, playing them a painstakingly reconstructed rendition of a yelp that she thinks may be a greeting. In French Polynesia, behavioral ecologist Ellen Garland of the University of St. Andrews in Scotland listens to humpback songs, mapping how they are tweaked, learned and shared by whales across the South Pacific. These settings are stark and gorgeous, their isolation artfully shown through silent, foggy mornings and endless cobalt seas. In a film fundamentally about oceans filled with sound, ample quiet rests on the surface.

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Directed by Drew Xanthopoulos, Fathom portrays humpbacks and other whales as complex, highly social beings without overstated anthropomorphism. In one goose bump–inducing scene, Garland’s narration identifies whales’ social similarities to humans, but set in a totally different environment. Perceiving each other chiefly with sound cast over stupefying distances, “whales evolved to build relationships in the dark,” Garland says.

Fathom also gives an intimate look at what scientists undertake to find humpbacks in the vast ocean. Equipment breaks. Whales prove unpredictable. Strategies must change on the fly. These moments communicate the tough realities of science and the resilience needed for successful research.

Much of the film is immersed in scenes like these, between troubleshooting and long waits on boat surveys. At times, the film’s pace languishes; connections to greater perspectives, such as the possibility of a globally interlinked song culture, are touched on but not fully examined.

Nonetheless, Fournet’s simple distillation of her complex quest lingers: “I’m trying to start a conversation.” Her words remind us that Fathom is inherently seated at the threshold of unfathomable territory.

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Watch a trailer for Fathom. More

The first genetically modified mosquitoes that will be allowed to fly free outdoors in the United States have started reaching the age for mating in the Florida Keys.

In a test of the biotech company Oxitec’s GM male mosquitoes for pest control, these Aedes aegypti started growing from tiny eggs set out in toaster-sized, hexagonal boxes on suburban private properties in late April. On May 12, experiment monitors confirmed that males had matured enough to start flying off on their own to court American female mosquitoes.

This short-term Florida experiment marks the first outdoor test in the United States of a strain of GM male mosquitoes as a highly targeted pest control strategy. This strain is engineered to shrink local populations of Ae. aegypti, a mosquito species that spreads dengue and Zika (SN: 7/29/16). That could start happening now that the GM mosquitoes have reached mating age because their genetics makes them such terrible choices as dads.

The mosquitoes now waving distinctively masculine (extra fluffy) antennae in Florida carry genetic add-ons that block development in females. No female larvae should survive to adulthood in the wild, says molecular biologist Nathan Rose, Oxitec’s chief of regulatory affairs. Half the released males’ sons, however, will carry dad’s daughter-killing trait. The sons of the bad dads can go on to trick a new generation of females into unwise mating decisions and doomed daughters (SN: 1/8/09).

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The trait is not designed to last in an area’s mosquitoes, though. The genetics just follow the same old rules of natural inheritance that mosquitoes and people follow: Traits pass to some offspring and not others. Only half a bad dad’s sons will carry the daughter-killing trait. The others will sire normal mosquito families.

Imagined versions of live-mosquito pest control in Florida have been both glorified and savaged in spirited community meetings for some time (SN: 8/22/20). But now it’s real. “I’m sure you can understand why we’re so excited,” said Andrea Leal, executive director of the Florida Keys Mosquito Control District, at the mosquito test (virtual) kickoff April 29.

The debate over these transgenic Ae. aegypti mosquitoes has gone on so long that Oxitec has upgraded its original more coddled version with one that is essentially plug and play. The newer strain, dubbed OX5034, no longer needs a breeding colony with its (biting) females and antibiotics in easy reach of the release area to produce fresh males.

Instead, Oxitec can just ship eggs in a phase of suspended development from its home base in Abingdon, England, to whatever location around the world, high-tech or not, wants to deploy them. Brazil has already tested this OX5034 strain and gone through the regulatory process to permit Oxitec to sell it there.

The targets for these potential living pest controls will be just their own kind. They represent only about 4 percent of the combined populations of the 45 or so mosquito species whining around the Keys. Other species get annoying, and a more recent invader, Ae. albopictus, can also spread dengue and Zika to some extent. Yet Leal blames just about all the current human disease spread by mosquitoes in the Keys, including last year’s dengue outbreak, on Ae. aegypti.

It’s one of the top three mosquitoes in the world in the number of diseases it can spread, says Don Yee, an aquatic ecologist at the University of Southern Mississippi in Hattiesburg, who studies mosquitoes (SN: 3/31/21). His lab has linked at least three dozen human pathogens, including some viruses and worms, to Ae. aegypti. Although most mosquitoes lurk outdoors in vegetation, this one loves humankind. In the tropics, “the adults are literally resting on the walls or the ceiling,” he says. “They’re hanging around the bathroom.” The species bites humans for more than half of its blood meals.

In a long-running battle with this beast, staff in Florida in late April added water to boxes of shipped eggs and set them out at selected suburban private properties on Vaca, Cudjoe and Ramrod Keys. Other spots, with no added mosquitoes, will be watched as controls. All locations were chosen in part because American-hatched females of the same species were already there to be wooed, Rose says.

Toaster-sized hexagonal boxes (one pictured) that contain eggs of genetically modified Aedes aegypti were set out on selected private property in the Keys in late April. There the males develop normally — and then fly away to mate.Oxitec

Males typically don’t billow out of their boxes in a gray cloud but emerge sporadically, a few at a time. If all goes well in this preliminary test, up to 12,000 GM mosquitoes in total across the release sites will take to the air each week for 12 weeks.

Neighboring households will host mosquito traps to monitor how far from the nursery boxes the Oxitec GM males tend to fly. That’s data that the U.S. Environmental Protection Agency wants to see. Based on distance tests elsewhere, 50 meters might be the median, Rose estimates. 

The distance matters because pest controllers want to keep the free-flying GM mosquitoes away from outdoor sources of the antibiotic tetracycline. That’s the substance the genetic engineers use as an off switch for the self-destruct mechanism in female larvae. Rearing facilities supply the antibiotic to larvae, turning off the lethal genetics and letting females survive in a lab to lay eggs for the next generation.

If GM males loosed in Florida happened to breed with a female that lays eggs in some puddle of water laced with the right concentration of tetracycline, daughters that inherited the switch could survive to adulthood as biters and breeders. The main possible sources in the Keys would be sewage treatment plants, Rose says. The test designers say they have selected sites well away from them.

After the distance tests, bigger releases still start looking at how well males fare and whether pest numbers shrink. Up to 20 million Oxitec mosquitoes in total could be released in tests running into the fall.

Despite some high-profile protests, finding people to host the boxes was not hard, Rose says. “We were oversubscribed.” At public hearings, the critics of the project typically outshout the fans. Yet there’s also support. In a 2016 nonbinding referendum on using GM mosquitoes, 31 of 33 precincts in Monroe County, which comprises the Keys, voted yes for the test release. Twenty of those victories were competitive though, not reaching 60 percent.

The males being released rely on a live-sons/dead-daughters strategy. That’s a change from the earlier strain of Oxitec mosquitoes. Those males sabotaged all offspring regardless of sex. The change came during the genetic redesign that permits an egg-shipping strategy. Surviving sons, however, mean the nonengineered genes in the new Oxitec strain can mix into the Florida population more than in the original version.

Those mixed-in genes from the test are “unlikely” to strengthen Floridian mosquitoes’ powers to spread disease, researchers from the EPA and the U.S. Centers for Disease Control and Prevention wrote in a May 1, 2020 memorandum. Many factors besides mosquito genetics affect how a disease spreads, the reviewers noted. Oxitec will be monitoring for mixing.

There may be at least one upside to mixing, Rose says. The lab colonies have little resistance to some common pesticides such as permethrin that the Floridian mosquitoes barely seem to notice.

Pesticide resistance in the Keys is what drives a lot of the interest in GM techniques, says chemist Phil Goodman, who chairs the local mosquito control district’s board of commissioners. During the dengue outbreak in 2009 and 2010, the first one in decades, the district discovered that its spray program had just about zero effect on Ae. aegypti. With some rethinking of the program’s chemicals, the control district can now wipe out up to 50 percent of mosquitoes of this species in a treated area. That’s not great control, at best. Then when bad weather intervenes for days in a row, the mosquitoes rebound, Goodman says.

The invasive mosquito species Aedes aegypti (shown), which can spread Zika, dengue and yellow fever, is now under attack in the Florida Keys by GM males genetically tweaked to sabotage the American mosquito populations.Joao Paulo Burini/Moment/Getty Images Plus

Since that 2009–2010 outbreak, catching dengue in Florida instead of just through foreign travel has become more common. In 2020, an unusually bad year for dengue, Florida reported 70 cases caught locally, according to the CDC’s provisional tally. 

Traditional pesticides can mess with creatures besides their pest targets, and some critics of the GMO mosquitoes also worry about unexpected ecological effects. Yet success of the Oxitec mosquitoes in slamming the current pests should not cause some disastrous shortage of food or pollination for natives, Yee says. Ae. aegypti invaded North America within the past four centuries, probably too short a time to become absolutely necessary for some native North American predator or plant.

For more details on pretrial tests and data, the Mosquito Control District has now posted a swarm of documents about the GM mosquitoes. The EPA’s summary of Oxitec’s tests, for instance, reports no effects noticed for feeding the aquatic mosquito larvae to crawfish.

Yee doesn’t worry much about either crustaceans or fish eating the larvae. “That’s somewhat analogous to saying, well, we’re concerned about releasing buffalo back into the prairies of the Midwest because they might get eaten by lions,” he says. Crawfish and fish, he notes, don’t naturally inhabit the small containers of still water where Ae. aegypti mosquitoes breed.

Still, new mosquito-fighting options are springing up: Radiation techniques might become precise enough to sterilize males but leave them attractive enough to fool females into pointless mating. And researchers are developing other genetic ways to weaponize mosquitoes against their own kind.

One technique that uses no GM wizardry just infects mosquitoes with Wolbachia bacteria that make biting unlikely to spread dengue. The latest data from Mexico and Columbia suggest this infection “could be effective in the southern U.S. and across the Caribbean,” says biologist Scott O’Neil, based in Ho Chi Minh City, Vietnam, founder of the World Mosquito Program.

He has no plans for working in the United States but is instead focusing on places with much worse dengue problems. His version of the Wolbachia strategy just makes bites less dangerous (SN: 6/29/12). The mosquito population doesn’t shrink or grow less bloodthirsty, so this approach might not appeal to Floridians anyway. More

Slathering corals in a common antibiotic seems to temporarily soothe a mysterious tissue-eating disease, new research suggests.

Just off Florida, a type of coral infected with stony coral tissue loss disease, or SCTLD, showed widespread improvement several months after being treated with amoxicillin, researchers report April 21 in Scientific Reports. While the deadly disease eventually reappeared, the results provide a spot of good news while scientists continue the search for what causes it.

“The antibiotic treatments give the corals a break,” says Erin Shilling, a coral researcher at Florida Atlantic University’s Harbor Branch Oceanographic Institute in Fort Pierce. “It’s very good at halting the lesions it’s applied to.”

Divers discovered SCTLD on reefs near Miami in 2014. Characterized by white lesions that rapidly eat away at coral tissue, the disease plagues nearly all of the Great Florida Reef, which spans 580 kilometers from St. Lucie Inlet in Marin County to Dry Tortugas National Park beyond the Florida Keys. In recent years, SCTLD has spread to reefs in the Caribbean (SN: 7/9/19).

As scientists search for the cause, they are left to treat the lesions through trial and error. Two treatments that show promise involve divers applying a chlorinated epoxy or an amoxicillin paste to infected patches. “We wanted to experimentally assess these techniques to see if they’re as effective as people have been reporting anecdotally,” Shilling says.In April 2019, Shilling and colleagues identified 95 lesions on 32 colonies of great star coral (Montastraea cavernosa) off Florida’s east coast. The scientists dug trenches into the corals around the lesions to separate diseased tissue from healthy tissue, then filled the moats and covered the diseased patches with the antibiotic paste or chlorinated epoxy and monitored the corals over 11 months.

Treatment with an amoxicillin paste (white bands, left) stopped a tissue-eating lesion from spreading over a great star coral colony up to 11 months later (right).E.N. Shilling, I.R. Combs and J.D. Voss/Scientific Reports 2021

Within about three months of the treatment, some 95 percent of infected coral tissues treated with amoxicillin had healed. Meanwhile, only about 20 percent of infected tissue treated with chlorinated epoxy had healed in that time — no better than untreated lesions. 

But a one-and-done treatment doesn’t stop new lesions from popping up over time, the team found. And some key questions remain unanswered, the scientists note, including how the treatment works on larger scales and what, if any, longer-term side effects the antibiotic could have on the corals and their surrounding environment.“Erin’s work is fabulous,” says Karen Neely, a marine biologist at Nova Southeastern University in Fort Lauderdale, Fla. Neely and her colleagues see similar results in their two-year experiment at the Florida National Marine Sanctuary. The researchers used the same amoxicillin paste and chlorinated epoxy treatments on more than 2,300 lesions on upwards of 1,600 coral colonies representing eight species, including great star coral.Those antibiotic treatments were more than 95 percent effective across all species, Neely says. And spot-treating new lesions that popped up after the initial treatment appeared to stop corals from becoming reinfected over time. That study is currently undergoing peer-review in Frontiers in Marine Science.

“Overall, putting these corals in this treatment program saves them,” Neely says. “We don’t get happy endings very often, so that’s a nice one.” More

A Magellanic penguin in Brazil ingested a face mask. A hedgehog in England got itself entangled in a glove. An octopus off the coast of France was found seeking refuge under a mask.

Wildlife and ecosystems around the world are suffering from the impact of discarded single-use COVID-19 protective gear, researchers warn March 22 in Animal Biology. Latex gloves and polypropylene masks which protect people from the coronavirus are exacerbating the plastic pollution problem when not disposed of properly and are causing wildlife deaths (SN:11/20/20). The study is the first global documentation of the impacts of COVID-19 litter on wildlife via entanglement, entrapment and ingestion (SN:12/15/20).

In August 2020, volunteers cleaning canals in Leiden, Netherlands, chanced upon a perch — a type of freshwater fish — trapped inside a finger of a latex glove. The ensnared fish was the first recorded wildlife casualty caused by COVID-19 litter in the Netherlands. The find shocked two Leiden-based biologists — Auke-Florian Hiemstra and Liselotte Rambonnet — who wanted to know more about the extent of COVID-19 litter’s impact on wildlife. They embarked on an extensive search, online and in newspapers, to collate examples.

A perch found trapped in a latex glove (pictured) in a Leiden canal inspired two Dutch biologists to look into how discarded single-use PPE is impacting animals around the world.Auke-Florian Hiemstra

They found 28 such instances from all around the world, pointing to a larger, global problem.   The earliest reported victim was from April 2020: an American robin in Canada, which appears to have died after getting entangled in a face mask. Pets are at risk, too: In Philadelphia, a domestic cat ingested a glove, and a pet dog in Boston that had consumed a face mask. “Animals with plastic in their stomach could starve to death,” says Rambonnet, of Leiden University.

“What this paper does is give us insight to the extent of the [COVID-19] litter’s impact on wildlife, so we can make efforts to minimize the consequences,” says Anna Schwarz, a sustainable plastics researcher at TNO, an independent organization for applied scientific research in Utrecht, Netherlands. That could be a tall order: A report published by Hong Kong–based marine conservation organization OceansAsia, for instance, estimates that 1.56 billion face masks would have entered the world’s ocean last year, part of the 8 million to 12 million metric tons of plastic that reaches the oceans annually.

As the far-reaching impacts of COVID-19 litter on wildlife become more apparent over time, Hiemstra, of the Naturalis Biodiversity Center, and Rambonnet are relying on citizen scientists to help them continue monitoring the situation: At www.covidlitter.com, people from around the world can submit their observations of affected wildlife. To curb the growing hazards, the study authors recommend switching to reusables wherever possible, as well as cutting up disposal gloves and snipping the straps off of single-use masks to prevent animals from getting entangled or trapped in them.

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“The paper highlights the importance of proper waste management, especially the recycling or disposal of single-use materials,” says Schwarz.

But the situation isn’t always so dire. Some animals have commandeered discarded PPE for their own uses. COVID-19 litter has become so pervasive that birds have been observed using face masks and gloves as building materials for their nests. “Bird nests from 2020 are so easy to recognize,” says Hiemstra. More

The open ocean is a veritable soup of tiny critters, including newborn fishes. It’s hard to learn about them, though, because they are mere millimeters long and semitransparent. When netted from research vessels, their delicate body parts may get mashed or removed. Now, a partnership between scientists and scuba divers is giving researchers fresh perspectives on the secrets of larval fishes.

Underwater photos taken at night — when larval fishes migrate to within 200 meters of the ocean surface — reveal colors, body structures and behaviors that could never be seen in preserved specimens. Examining those same fishes back in the lab lets ichthyologists match the photographed larval fishes to known species, researchers report March 30 in Ichthyology & Herpetology.

Scientists at the Smithsonian Institution and the National Oceanic and Atmospheric Administration hatched a collaboration in 2016 with blackwater divers — who enter the ocean in the dark of night — to photograph larval fishes and collect them as specimens. With lights in hand, divers Jeff Milisen and Sarah Mayte snapped up-close photos of nearly 80 larval fishes, then gingerly captured and shipped them to scientists to be studied alongside their mugshots.

“Fish larvae that looked utterly drab as specimens have turned out to have brilliantly colored markings and fantastic structures,” says Ai Nonaka, a larval fish expert at the Smithsonian’s National Museum of Natural History in Washington, D.C.

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Fragile appendages

Specialists like Nonaka sort out larval fish identities by looking at body shapes and minuscule features through microscopes and by analyzing DNA of larval tissue. Unlike their swimming parents, fish larvae drift on currents, and their strange body parts — adaptations for a drifting lifestyle — make larvae look nothing like adults. 

“Larval fishes are extremely difficult to identify,” says Dave Johnson, an ichthyologist also at the Smithsonian. Scientists have mistakenly given larval fishes new scientific names, not recognizing them as early life stages of known species.

Because larval fishes are soft and fragile, they don’t travel well. Larvae lose fins and other delicate structures that evoke their behavior. The scalloped ribbonfish (Zu cristatus) larva, for example, has spaghetti-like ornamental fins sprinkled with white spots that get broken off on specimens. The way these ornamental structures appear to flow out like tentacles in the images of wild larvae suggests the larvae could be jellyfish mimics, say the study authors.

Scalloped ribbonfish (Zu cristatus) larva in the oceanJ. Milisen

Scalloped ribbonfish (Z. cristatus) larva specimenA. Nonaka/Smithsonian NMNH

The trailing guts of a barbeled dragonfish (Aristostomias sp.) larva get mashed or broken off altogether, but the undersea photo reveals it coiled up into a tight corkscrew. Nonaka and Johnson confess that scientists don’t yet understand the function of the trailing guts seen in some larval fishes. One theory is that exposed innards might somehow increase digestion efficiency, while another suggests they could confuse predators.

Barbeled dragonfish (Aristostomias sp.) larva in the oceanJ. Milisen

Barbeled dragonfish (Aristostomias sp.) larva specimenA. Nonaka/Smithsonian NMNH

Hidden colors

Ethanol preservation of specimens repels bacteria and fungi, but leaches out colors. The three-spot righteye flounder (Samariscus triocellatus) larva, bone white as a specimen, is bright blue. Its dorsal and anal fins are fringed with white, and rows of yellow spots dot the base of the fin rays. While their function has yet to be studied, it’s possible that these borders create a flickering visual effect to help the fish escape from predators, suggests Geoff Moser, a retired NOAA fisheries biologist not involved with the study. Called “flicker fusion,” it’s been examined in other animals such as striped snakes as a form of camouflage on the go.

Three-spot righteye flounder (Samariscus triocellatus) larva in the oceanJ. Milisen

Three-spot righteye flounder (S. triocellatus) larva specimenA. Nonaka/Smithsonian NMNH

The deep-sea tripodfish (Bathymicrops sp.) is plain and pale when prepared as a specimen and uniform brown as an adult fish — not exactly a looker. But the larva appears to have donned a clown costume with large white and orange polka dots flecked on its otherwise blue-hued body. In an ethanol specimen, its pectoral fins look soft and ghostly, whereas the living larva sports flamboyant, spiky and spotted fins. The function of the coloration is unknown. says Nonaka, but it could also be a flicker fusion trick.

Deep-sea tripodfish (Bathymicrops sp.) larva in the oceanJ. Milisen

Deep-sea tripodfish (Bathymicrops sp.) larva specimenA. Nonaka/Smithsonian NMNH

Fishy behavior

In larval specimens, scientists can observe some structures as evidence of behaviors. But undersea observations of wild larval fishes can show what they’re really up to when they are alive. The larva of the barred conger (Ariosoma fasciatum) is super flat, quite unlike the cylindrical adult. Yet a photo shows that it swims like an adult barred conger, by undulating its long body laterally. So, while it’s more svelte as a larva, it’s got some of the adult movements down.

Barred conger (Ariosoma fasciatum) larva in the oceanJ. Milisen

Barred conger (A. fasciatum) larva specimenA. Nonaka/Smithsonian NMNH

Undersea observations can also reveal associations larvae have with other marine animals, including other tiny critters that also ride the currents. For example, a petite Pacific pomfret (Brama japonica) larva was caught on camera riding on a jellyfish. That’s a discovery that the study authors were unwilling to even speculate about. Although larval fishes have been seen taking shelter in the tentacles of jellies, hitching a ride on top of a jellyfish seems like an odd twist on that behavior.

A pacific pomfret (Brama japonica) larva (pictured from three angles) in the ocean, riding a jellyfishJ. Milisen (photos); E. Otwell/Science News (collage)

Pacific pomfret (Brama japonica) larva specimenA. Nonaka/Smithsonian NMNH

Each larval fish that gets identified by scientists sets the stage for conservation. By knowing where larval fishes of particular species live, researchers can better advise on how to manage the ocean ecosystems the fishes depend on for survival.

Conservation planning also requires knowledge of behavior (SN: 12/30/10). So photographing larval fishes and making their specimens available for identification means researchers get a handle on fishes’ behavioral adaptations for survival in the wild.

“I’ve been working with fish larvae for over 40 years,” says Moser. “The chance to see these larvae in their environment was a wonderful advance in our scientific endeavors.” More