The number that anchors everything is about 600 volts. That is the peak discharge an electric eel can deliver, several times the roughly 120 volts of a North American wall socket. The figure is stranger than it looks: no single part of the eel produces anything close to that. The voltage is assembled, cell by cell, out of thousands of much smaller contributions.

Despite its name, the electric eel is a type of  knifefish, and as much as four-fifths of its roughly two-metre body is given over to one job: making electricity. 

Each of the specialised cells, called electrocytes, produces only a tiny voltage on its own. A single electrocyte fires at around 150 millivolts, about a seventh of a volt. Stack thousands of them in series and fire them at once, and the small jolts sum the way cells in a battery do. The cells are linked in series to build voltage and in parallel to build current, channelling the combined output toward a target.

The comparison to a battery is more than loose metaphor. The arrangement has long been likened to Alessandro Volta’s voltaic pile of 1799, the first synthetic battery, which stacked metal discs to do what the eel does with living tissue.

Researchers have since built the principle back the other way. A team at the University of Fribourg, working with stacked ion-selective hydrogels to mimic the eel’s total of up to 600 volts, assembled an artificial version that generated 110 volts when thousands of its cells were triggered together.

For most of the time we have known about the eel, the assumption was that it shocked prey underwater and left it at that. Then Kenneth Catania filmed something different.

The Vanderbilt biologist documented and filmed eels rising out of the water to press their chin against a partially submerged threat. The contact point matters: the current exits through the chin into the target and returns to the eel’s tail, completing the circuit through the animal it is attacking rather than dissipating into the surrounding water.

The measurements showed both voltage and current to the target rising the higher the eel climbed. Catania read the behaviour as a defensive move, a way to drive a shock home with maximum effect. This, he wrote, lets the eels deliver shocks “with a maximum amount of power to partially submerged land animals that invade their territory”. He also proposed that the manoeuvre could have arisen in steps, with “each stage” providing “a successive advantage, suggesting how it may have evolved.”

The discovery did more than describe new behaviour — it rehabilitated an old story. 

In 1800, the naturalist Alexander von Humboldt described eels in a South American pool attacking horses, with two horses stunned and drowned in the first five minutes of the skirmish. For roughly two centuries afterward, no scientific reports of any such leaping attack appeared, and the tale was treated with skepticism. Catania felt the same pull of disbelief. “The first time I read von Humboldt’s tale, I thought it was completely bizarre,” he said. “Why would the eels attack the horses instead of swimming away?”

The filmed leaps offered an answer. Catania argued that the behaviour, most likely a dry-season defence when crowded eels are cornered in shrinking pools, fit Humboldt’s description closely enough that “it seems reasonable to suggest” the naturalist had watched a similar eel behaviour on 19 March 1800. The hedge is his own, and it stays a careful inference rather than proof. Other researchers found the work persuasive all the same. In the view of James Albert, a University of Louisiana at Lafayette biologist who studies how electric fish evolved their use of electricity, the results “are literally rewriting the book on what we know about electric behaviors of the electric eel.”

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When researchers at the Australian National University played recordings of superb lyrebird mimicry to grey shrike-thrushes, the shrike-thrushes responded to the fakes much as they would to one of their own. As lead author Anastasia Dalziell put it, “Surprisingly, strike-thrushes approached the speaker broadcasting mimicked songs as well as the shrike-thrushes’ own song.”

The superb lyrebird (Menura novaehollandiae) is a large ground-dwelling songbird of the forests of south-eastern Australia, and most of what it sings is borrowed. The bulk of a male’s song is imitation, drawn overwhelmingly from other forest birds. During the breeding season a male will mimic roughly 20 to 25 species.

Dalziell and Robert Magrath measured how close the copies actually were in a study titled “Fooling the Experts.” The acoustic match for grey shrike-thrush song was tight enough that the model species could not reliably tell the imitation from the real thing. “Grey shrike-thrushes sing a complex and beautiful song, but lyrebirds can accurately mimic them all the same,” Dalziell said.

Two cautions belong here. This was a playback experiment measuring acoustic similarity for one model species, not a blanket finding that every lyrebird copy is indistinguishable. The shrike-thrushes also did better at discriminating when given other contextual cues, so “fooled” sits closer to “often fooled” than to “always fooled.”

The chainsaws and car alarms that made the bird globally famous come with their own footnote. The celebrated imitations of saws and drills trace largely to captive birds, including a male named Chook at Adelaide Zoo who died in 2011. Wild lyrebirds overwhelmingly mimic natural forest sounds. 

Look closely and it get’s more interesting. A male does not simply replay everything he knows at maximum length. In the “Fooling the Experts” analysis, the lyrebirds abridged the songs they copied, trimming repeated notes, which is consistent with a trade-off between showing off accuracy and packing in variety.

Dalziell described it this way: “This mimicry is the accomplishment of years of practice and is probably used to show female lyrebirds the quality of the singer.” Note the “probably.” It is offered as a hypothesis, not a verdict.

A 2021 study added a stranger wrinkle. Dalziell and colleagues found that males create an acoustic illusion of a whole mixed-species mobbing flock at very particular moments. As Dalziell put it, “The male lyrebird recreates that sound when a potential mate tries to leave a displaying male without copulating, or during copulation itself.” The illusion may work as a sensory trap rather than a simple display of extravagance, though the Cornell write-up is careful that it is not clear exactly how males benefit.

The tidy phrase “all in service of winning over a mate” runs into a basic problem: females mimic too. The first systematic study of female superb lyrebird song found they are skilled mimics in their own right, copying at least 19 species. Co-author Justin Welbergen noted that “The females imitated fewer bird calls than males but performed more imitations of hawks.” A trait that existed only to attract a mate would have no obvious reason to appear, in a different form, in the sex that does not display.

The function is plainly more than one thing. Courtship is the best-documented driver, and mimicry does peak in the breeding season. But the same skill turns up in what looks like deception during copulation, and in displays whose structure shifts depending on the moment. Each of these is a working hypothesis backed by an observational or playback study, not a closed case.

What the lyrebird exposes is perhaps a habit of ours, not of the bird’s. The temptation is to attach one clean purpose to a behaviour because one purpose is easy to tell as a story. The animal keeps refusing to cooperate. The most interesting thing about a bird that can imitate almost anything is that we still cannot say, with confidence, exactly why it bothers.

The post The Australian superb lyrebird can imitate almost any sound it has ever heard — chainsaws, camera shutters, car alarms, the calls of more than 20 other species — with enough accuracy that the birds being imitated often can’t tell the difference appeared first on Space Daily.