Every sense you have is free-riding. Vision works because the sun is running an enormous fusion reactor and throwing photons at everything for no charge. Hearing works because objects in the world make noise whether or not you are listening. Smell works because molecules evaporate. In every case the energy carrying the information was put there by something other than you, and your job is limited to catching it.
Echolocation does not get that deal. An echolocating animal has to manufacture the signal, project it, wait, and interpret whatever fraction returns, and it pays for the whole transaction out of its own metabolism. That single structural difference generates almost every interesting property of the sense, including the ones that look like paradoxes.
Consider one. A bat’s echolocation call is among the loudest sounds produced by any animal, reaching intensities above one hundred and thirty decibels measured close to the mouth, comparable to standing near a jet engine. And a bat can echolocate for hours while flying, which is already the most metabolically expensive form of locomotion in the animal kingdom, without the sonar adding much to the bill. The reason is that the muscles driving the call are coupled to the muscles driving the wingbeat, so the bat gets the sound nearly free by piggybacking on something it was doing anyway. Active sensing is expensive in principle, and the animals that use it have spent millions of years finding ways not to pay.
What active sensing actually is
The distinction worth holding is between passive and active sensing, and it is not a distinction about sophistication. It is about who supplies the energy.
Passive senses detect energy already present. Active senses generate a probe, emit it, and analyze what comes back. The costs are obvious: you pay metabolically, you advertise your position to anything that can detect your probe, and your range is bounded by how much power you can afford. The advantages are equally clear and less appreciated. You control the timing of every measurement, which means you know exactly when the signal left and can compute delay directly. You control the waveform, which means you can shape the probe to the question. You control the direction. And you work in the dark, in mud, in turbid water, and in any other condition where passive sensing collapses.
Echolocation is the acoustic version. Electrolocation, in the weakly electric fish, is the same principle with an electric field as the probe. Active touch is a version of it too, since a rat sweeping its whiskers across a surface at a controlled frequency is generating a probe signal and analyzing its distortion. Even human vision has an active component, since eye movements are self-generated and the visual system knows about them. So does the whisking of a rat, the sniffing of a dog, and the tongue-flicking of a snake sampling air for its vomeronasal organ, all of which are rhythmic self-generated sampling behaviors under motor control rather than passive intake. The dogs whose working performance depends on sniff rate and pattern are running active sensing in the chemical domain, and the sniff is the probe.
Two structural facts follow immediately. First, active sensing is closed-loop by nature: the animal chooses the probe, gets a result, and adjusts the next probe based on it, which makes perception a motor problem rather than a receptive one. Second, an active sense produces distance for free. A passive listener hearing a sound has no idea how far away it started. An echolocating animal knows precisely when it emitted the call, so the delay between emission and echo is range, directly, with no inference required.
That second point is the reason echolocation is fundamentally a spatial sense rather than an auditory one, and it is the reason a bat’s world is measured in milliseconds.
There is a third structural consequence that gets less attention and matters more than it should. An active sensor has to solve the problem of not deafening itself. The outgoing call is many orders of magnitude louder than the returning echo, and the two are separated by only a few milliseconds, which means the receiver has to survive the transmission and recover in time to detect something almost inaudible. Bats handle it with middle ear muscles that contract just before each call and relax immediately after, attenuating their own emission by roughly twenty decibels and releasing in time for the echo. That contraction and release cycle runs at up to two hundred times per second during the terminal buzz. The animal is winking its own ears shut and open, faster than a hummingbird beats its wings, for every single measurement it takes.
The bat’s problem, in numbers
Sound travels at roughly three hundred and forty meters per second in air, which means an echo from a target one meter away returns in about six milliseconds. Bats detect and act on targets at ranges from a few meters down to a few centimeters, so the entire perceptual loop runs in single-digit milliseconds.
The temporal resolution required is extraordinary. Big brown bats can discriminate arrival time differences on the order of a microsecond or less, which corresponds to distance differences under a millimeter. That is a nervous system resolving timing at a scale finer than the duration of an action potential, achieved through populations of neurons rather than any individual cell.
The call design reflects the task, and the two main strategies are worth distinguishing because they solve different problems. Frequency-modulated calls sweep rapidly downward through a range of frequencies in a few milliseconds, which gives excellent range resolution because a broadband sweep can be correlated precisely against its echo. Constant-frequency calls hold a narrow band for much longer, which gives poor range resolution and superb velocity resolution, because a moving target shifts the echo frequency by a measurable amount.
The horseshoe bats built an entire perceptual system around that second strategy, and it is one of the more elegant pieces of biological engineering on record. Their cochlea has an acoustic fovea, an over-represented region tuned with extreme precision to a narrow frequency band. The bat then adjusts its outgoing call frequency downward to compensate for its own flight speed, so that the returning echo lands exactly in the fovea regardless of how fast the bat is going. This is called Doppler shift compensation, and it means the animal is actively tuning its transmitter to keep its receiver in the sweet spot. Within that band, the bat can detect the tiny frequency and amplitude flutter produced by an insect’s beating wings, which lets it find a moth against a background of dense foliage that would otherwise swamp the echo.
Then there is the terminal buzz. As a bat closes on prey, call rate climbs from around ten per second during search to something near two hundred per second at capture, which requires laryngeal muscles capable of contracting faster than almost any other vertebrate muscle. The information rate goes up precisely when the target is about to escape.
Beam control belongs alongside call design as an active variable. Bats adjust the width of their sonar beam according to task, broadening it during search to cover more space and narrowing it during approach to concentrate energy on the target, and they steer it independently of head direction in some species. Egyptian fruit bats have been shown to point the maximum-slope edges of the beam at a target rather than the center, which sounds counterintuitive until you consider that the steepest part of a gradient carries the most localization information per unit of signal. The animal is not aiming its flashlight at the object. It is aiming the edge of the beam, where a small angular error produces a large intensity change, because that is where the precision lives.
Echolocation underwater, and the organ in the forehead
Water changes the physics enough that the marine solution looks nothing like the aerial one, despite solving the same problem.
Sound travels roughly four and a half times faster in seawater than in air and attenuates far less, which extends the useful range enormously. Sperm whales generate the loudest sounds any animal makes, with source levels reported above two hundred decibels in water. The tradeoff is that water is acoustically much closer to flesh than air is, which makes it harder to get sound out of a body and into the medium efficiently, and harder to keep a beam from spreading.
Toothed whales solved it with dedicated hardware that has no terrestrial equivalent. Sound is generated not in the larynx but at the phonic lips, structures in the nasal passages below the blowhole, which are driven by pressurized air. That sound then passes through the melon, a fatty structure in the forehead with a graded composition: lipids at the center have a different sound speed than lipids at the periphery, which makes the melon an acoustic lens that focuses the beam forward. Different species produce beams of different widths, and animals can adjust beam shape and direction by changing melon geometry with facial musculature.
Reception is stranger still. Toothed whales have no functional external ear canal. Sound enters through the lower jaw, where a fatty channel in the mandible conducts vibration back to the middle ear, which is itself acoustically isolated from the skull by air sinuses so the two ears can be independently addressed. The jaw is the ear.
The depth problem adds a constraint no bat faces. A sperm whale hunting at a thousand meters is operating under roughly a hundred atmospheres, which collapses air spaces, and the entire sound production system runs on air that has to be recycled rather than exhaled. The animal circulates a fixed volume between nasal sacs, clicking continuously through dives lasting the better part of an hour, on air it cannot replenish until it surfaces. The deep-diving species whose foraging behavior is hardest to observe directly are doing all of their sensing on a closed pneumatic loop.
The sperm whale takes it furthest. Its head is roughly a third of its body length and contains the spermaceti organ, a mass of waxy oil through which sound is bounced between an anterior air sac and a posterior air sac before being emitted, producing the multi-pulse click structure that lets researchers estimate an individual whale’s body length from the interval between pulses. The Eastern Caribbean populations under the closest long-term acoustic observation are studied largely through those clicks, which do double duty as sonar and as social signal.
That dual function is the recent story. Analysis of coda structure in sperm whales has identified systematic variation in rhythm, tempo, and ornamentation that is sensitive to conversational context, which the researchers described as a combinatorial coding system. The dual-use arrangement also produces a specific hazard. A sensing system that broadcasts at two hundred decibels is audible to anything with ears for many kilometers, which is how whalers found sperm whales acoustically long before anyone understood what the clicks were for. An echolocating animal cannot hunt quietly, and the ones that need to hunt quietly, like the orca populations that specialize on marine mammal prey, tend to go acoustically silent and hunt by passive listening instead. The same organ that finds squid at depth is producing structured signals to other whales, and the dialect systems documented in other cetacean populations suggest that acoustic identity and acoustic sensing have been intertwined in this group for a long time. The bottlenose dolphins whose signature whistles function as individual labels run the two channels in parallel, whistles for social work and clicks for sensing, and the beluga that spent years working a Norwegian coastline within earshot of boat traffic demonstrated how quickly an animal operating on sound adjusts to an acoustic environment nobody designed for it.
The cocktail party nightmare, and why it is not solved by jamming avoidance
Here is a problem that looks fatal on paper. Hundreds of thousands of bats leave a cave within minutes, all emitting loud calls in overlapping frequency bands, all listening for echoes thousands of times fainter than the calls around them. The signal-to-noise arithmetic says none of them should be able to perceive anything.
The textbook answer for years was jamming avoidance: bats shift their call frequencies away from those of neighbors to carve out private channels. It is a satisfying explanation and the evidence for it in wild bats is weaker than its popularity suggests. On-board recordings from bats flying in dense groups found no jamming avoidance response, and other work found that bats aggregate to improve prey search but may be impaired when density gets too high, which is the opposite of a solved problem.
A 2025 study tracked tens of bats simultaneously while recording echolocation from individuals with onboard microphones, and combined that with a sensorimotor model. What it found is that the bats deal with the problem largely by spreading out in space rapidly on emergence, and by adjusting their sensorimotor behavior to reduce acoustic masking, rather than by clever frequency partitioning. The solution is geometric and behavioral rather than signal-theoretic.
That is worth sitting with as a general lesson about how biological systems handle interference. The engineer’s instinct is a coding solution. The bats’ solution is to get away from each other, accept degraded sensing during the worst of it, and rely on the fact that a collision at low relative velocity is survivable. Robustness rather than optimality, which is the recurring answer whenever a biological system faces a problem that looks unsolvable.
There is a related finding about eavesdropping that inverts the framing entirely. Because echolocation broadcasts, a bat can hear the terminal buzz of a neighbor and infer that the neighbor found food, which turns the conspecific interference problem into an information source. Bats do exploit this, converging on individuals whose call patterns indicate a capture, which means the same acoustic clutter that degrades individual sensing supports a form of collective foraging. Whether interference is a cost or a benefit depends on density, and the crossover point is where the collective behavior of the group becomes the relevant unit rather than the individual sensor.
The 2024 result that changed what echolocation is for
The standing assumption about echolocation was that it is a short-range sense. A bat’s calls are directional and attenuate quickly, useful within meters, which meant navigation over kilometers had to be handled by something else: vision, magnetic sense, olfaction, or landmark memory built from those.
That assumption collapsed in 2024. Researchers translocated wild Kuhl’s pipistrelle bats several kilometers from their colony and tracked their homing using a reverse-GPS system, while systematically manipulating vision, magnetic sense, and olfaction to isolate what the animals were actually using. The demonstration of acoustic cognitive map-based navigation in echolocating bats showed that bats can identify their location after translocation and perform kilometer-scale map-based navigation using echolocation alone, with navigation improving further when vision was also available.
The supporting work was a large-scale acoustic model of the environment showing how the spatial distribution of echo-generating features supplies enough information to localize. The bat is not seeing a landmark at three kilometers. It is sampling the local acoustic scene, recognizing the pattern of returns from nearby structure, and matching it against a stored representation of an area much larger than any single call can reach.
That reframes echolocation from a proximity sensor into an instrument capable of supporting a genuine cognitive map built entirely from self-generated sound. The comparison worth making is to someone finding their way across a city at night with a flashlight: the beam reaches a few meters, but the accumulated pattern of what the beam has revealed, matched against memory, is enough to know where you are.
A companion result on how the map gets built is equally interesting. Young bats extend their exploratory range outward from the roost over months, in progressively longer excursions, which means the acoustic map is learned rather than inherited and requires a developmental period of accumulating coverage. That has a conservation implication nobody planned for: an animal whose navigation depends on a learned acoustic model of specific terrain is vulnerable to that terrain changing, in a way an animal navigating by magnetic field or star compass is not. Development, in this system, is map-building. The elephant matriarchs whose knowledge of water sources is accumulated over decades and dies with them are running the same vulnerability on a longer timescale, and the populations studied under different ecological pressures show how much of a spatial repertoire turns out to be individual experience rather than species instinct.
Electric fish, and the sense with no delay to measure
Weakly electric fish run active sensing on a completely different physical channel, and the differences are as informative as the similarities.
The electric organ, derived from modified muscle or nerve tissue, generates a discharge that establishes a field around the body. Objects with conductivity different from the surrounding water distort that field, and thousands of electroreceptors in the skin read the resulting pattern as an electrical image projected onto the body surface. Conductive objects, like other animals, focus current and brighten the image. Non-conductive objects, like rocks, produce shadows.
Two strategies exist. Wave-type fish produce a continuous quasi-sinusoidal discharge at a fixed individual frequency. Pulse-type fish produce discrete pulses with variable intervals.
The critical physical difference from echolocation is that there is no travel time. The electric field is established essentially instantaneously, which means the fish gets no range information from delay. Distance has to be inferred from the shape of the distortion, specifically from how blurred and spread out the electrical image is, since nearby objects produce sharp compact images and distant ones produce diffuse faint ones. That is a fundamentally harder inference problem than reading a clock, and the range is correspondingly short, on the order of a body length.
Interference produced one of the classic results in neuroethology. When two wave-type fish with similar discharge frequencies meet, the beat between their signals corrupts both their electrical images. The jamming avoidance response is the behavior that resolves it: each fish shifts its frequency away from the other, one going up and one going down. What makes it a landmark is that the neural computation was worked out completely, from receptor to behavior, in one of the first full sensorimotor circuits ever traced. It is also a computation the fish cannot do with information available at any single point on its body, since determining whether a neighbor’s frequency is higher or lower requires comparing how amplitude and phase modulations covary across separated skin regions, which means the answer exists only in the population and not in any receptor. The fish must determine whether the neighbor’s frequency is above or below its own, which requires comparing amplitude and phase modulations across body regions, and the circuitry doing it has been mapped.
Recent work has complicated the tidy picture. Studies of mormyrid electric fish have raised the question of whether interactive electrical behavior between individuals reflects jamming avoidance at all, or whether the echo responses observed are social signaling that happens to affect timing. Same observation, two interpretations, and the field has not settled it.
The electric fish case also demonstrates something echolocation obscures, which is that active sensing and active signaling are frequently the same apparatus. An electric organ discharge is simultaneously a probe of the environment and a broadcast of species, sex, and individual identity, because the waveform carries all of it. Any fish reading its own field distortions is also being read by every electroreceptive animal nearby, including catfish and electric eels that hunt by passive electroreception and have no organ of their own. The sensor is a beacon, and there is no setting on it that is not.
The arms race, and what prey did about it
An active sense broadcasts. That is the fundamental vulnerability, and moths exploited it.
Several moth lineages independently evolved ultrasonic hearing, in some cases with ears containing as few as one to four auditory receptor cells, tuned to bat call frequencies. A quiet call means a distant bat and triggers evasive turning. A loud call means an attacking bat and triggers an erratic dive. That is a two-cell threat assessment system, and it outperforms most of what gets built with a thousand times the hardware. The insects whose entire behavioral repertoire runs on a few hundred thousand neurons are a standing argument that neuron count predicts far less about capability than intuition suggests.
Tiger moths went further and started transmitting. They produce ultrasonic clicks from tymbal organs, and these serve at least three functions depending on the species. Some are aposematic, honestly advertising toxicity, and bats learn the association. Some are acoustic mimics, imitating the signals of toxic species without the chemistry. And some genuinely jam, with click trains dense and precisely timed enough to interfere with the bat’s ranging during the terminal buzz, causing measurable increases in miss distance.
The response from bats came in the form of stealth. Some species evolved allotonic frequencies outside the hearing range of local moths. Barbastelle bats reduced call intensity by a factor of ten to one hundred relative to typical aerial hawkers, becoming acoustically quiet enough to approach eared moths undetected, and accepting a shorter detection range as the cost. Other species gave up echolocating during the final approach entirely and listen passively for prey-generated sounds instead, which is an active sensor deliberately going dark.
The escalation continues into materials. Moth wing scales and thoracic fur have been shown to function as acoustic metamaterials, absorbing ultrasound at bat call frequencies and reducing echo strength substantially, which is stealth coating evolved by an insect. Some deaf moths carry it as pure passive defense with no detection system at all.
The timeline of this arms race is worth stating because it predates most of what people assume. Bat echolocation is on the order of fifty million years old, and moth ultrasonic hearing has evolved independently on the order of a dozen times or more across different lineages, which is a rate of convergence that only happens when the selection pressure is severe and the solution is anatomically cheap. An ear with two receptor cells is a small evolutionary purchase against a predator that announces its approach.
The insects running these countermeasures on a few hundred thousand neurons are worth keeping in mind whenever the sophistication of the bat system is being admired. Both sides of this arms race are impressive, and only one of them gets documentaries.
The countermeasures also reveal something about the limits of the bat system that the bat’s own performance obscures. A sensor that can be jammed by a moth clicking is a sensor with a narrow dynamic range at the moment it matters most, during the terminal buzz when the animal is committed to an intercept and sampling fastest. Peak performance and peak vulnerability arrive together, which is a design property rather than an accident, and it holds for engineered radar as much as for any biological system operating near its physical limits.
Who else does it, and how badly
Echolocation has evolved multiple times and the poor implementations are as informative as the good ones.
Oilbirds in South America and several swiftlet species in Asia echolocate with audible clicks in the low kilohertz range rather than ultrasound, which gives them wavelengths far too long for fine resolution. They can navigate caves in complete darkness and avoid walls. They cannot detect insects acoustically and forage visually. That is exactly what the physics predicts: resolution scales with frequency, and a bird clicking at a few kilohertz has a wavelength of centimeters, which sets a hard floor on the size of detectable objects.
The birds are the useful case precisely because they are bad at it. They demonstrate that echolocation is not a threshold capability an animal either has or lacks, but a continuum bounded by physics at one end and by hardware investment at the other. A bird that clicks audibly gets cave navigation and nothing more, because getting insect detection would require ultrasonic production, ultrasonic hearing, microsecond timing, and neural machinery to match, and no intermediate step on that path pays for itself unless something is already selecting for it. The long-distance migrants who navigate continentally without any of this are a reminder that most birds solved their spatial problems entirely differently.
Some shrews and tenrecs produce ultrasonic clicks used for short-range orientation, a rudimentary version that appears to help with immediate obstacle detection and little else.
Certain fruit bats in the genus Rousettus echolocate by clicking with the tongue rather than the larynx, an independent origin within bats themselves. And non-echolocating fruit bats have been found to produce faint clicks with their wings, which is a candidate for how the whole system might have started: a byproduct sound that turned out to carry information.
Human echolocation, and a visual cortex with no vision
People do it too, and the neural findings are the most interesting part of the whole subject.
Expert human echolocators, typically blind and typically using sharp tongue clicks, can determine object size, distance, shape, and material, discriminate two-dimensional shapes, detect a silent object across a room, and navigate unfamiliar environments. The skill is trainable rather than innate, sighted people can acquire useful competence in weeks, and performance improves with practice in the ordinary way any perceptual skill does.
The imaging work is what makes it consequential. In one study, researchers recorded clicks and their faint echoes using microphones placed in the ears of blind echolocation experts standing outdoors identifying objects, then replayed those recordings during functional imaging. The neural correlates of natural human echolocation in early and late blind experts showed activation in calcarine cortex, the primary visual area, in response to the echoes, with no corresponding difference in auditory cortex. In the early-blind participant, that calcarine activity was greater for echoes reflected from surfaces contralateral to the recording side, which is the spatial organization the visual system normally uses for light.
Blind non-echolocators do not show it. Sighted controls do not show it. Subsequent work has reported the same retinotopic-like organization in expert echolocators, along with recruitment of parahippocampal cortex for material properties, which is the same region that handles surface and texture processing for vision.
The implication is about what cortical tissue is actually for. Primary visual cortex is not a light-processing region that happens to be wired to the eyes. It is a spatial-representation engine, and given echoes instead of photons it will build spatial representations out of echoes, preserving the same contralateral organization. The modality is an input. The computation is the tissue.
What the popular account gets wrong
An audit, because this subject accumulates errors that sound authoritative.
Bats are blind is the durable one and it is simply false. No bat species is blind, most see reasonably well, some fruit bats have excellent vision, and the 2024 navigation work found bats do better with vision and echolocation together than with either alone. Echolocation supplements vision at night rather than replacing it.
Dolphins can stun prey with sound is a persistent claim with no supporting evidence. It has been tested and the acoustic energy involved is far below what would be required.
Echolocation gives a picture of the world, in the sense of a visual image, oversimplifies badly. The information available is genuinely different: excellent on range and texture and material, poor on anything a wavelength cannot resolve, and organized around a beam the animal points rather than a field of view it takes in. It is a different sense, not a substitute one.
Bats always avoid jamming by shifting frequency is the finding that has not held up in the wild, as the on-board recording work showed.
Whale strandings are caused by sonar deafening the animals conflates several things. There is real evidence linking certain naval sonar exercises to beaked whale strandings, and the leading mechanism involves behavioral disruption of diving patterns leading to decompression-related injury rather than acoustic damage to the hearing organ. The distinction matters for mitigation.
Echolocation is a supersense that would be great to have understates its costs. It is metabolically expensive, it broadcasts your position to everything that can hear it, it is useless beyond tens of meters in air, and it degrades badly in acoustically cluttered environments. Every animal using it also uses something else.
Only bats and dolphins echolocate is the taxonomic version and it undercounts substantially. Toothed whales as a group, several bird lineages, some shrews and tenrecs, at least one independent origin inside bats using tongue clicks rather than the larynx, and humans with training all do some version of it. Whether a given case counts depends on where the line is drawn between navigation-grade and prey-detection-grade, which is a continuum rather than a category. The same boundary trouble shows up wherever a capacity is treated as binary, including in the birds whose acoustic signals encode individual identity and regional origin.
Bats get tangled in your hair belongs here for completeness, since an animal that can resolve millimeter differences in target range at two hundred measurements per second is the least likely creature in the world to fly into something by accident.
The general principle underneath
Step back from bats and whales and fish and the thing worth extracting is a claim about perception generally.
Active sensing makes perception a motor act. The animal decides what to emit, when, in what direction, and with what waveform, and each decision is based on the result of the previous one. A bat approaching prey shortens its calls, raises its rate, narrows its beam, and adjusts frequency, continuously, in a closed loop running on a millisecond timescale. There is no clean separation between sensing and acting, because the sensing is acting.
The engineering consequence is that an active sensor is a controller, and controllers have stability requirements. Every parameter a bat adjusts, call rate, duration, bandwidth, intensity, beam width, is being set on the basis of the previous echo, which means the whole system is a feedback loop with a delay in it. Loops with delays oscillate if they are tuned wrong. That the bat can raise its sampling rate by a factor of twenty during the final two hundred milliseconds of an intercept, while continuously updating a range estimate, without the loop destabilizing, is a control-theory achievement that gets almost no attention next to the acoustics.
That framing turns out to apply well beyond the animals that obviously echolocate. Whisking rats, sniffing dogs, and the eye movements underlying human vision are all instances of the same architecture: generate a probe, evaluate the return, adjust the next probe. The architecture of sensory worlds looks different once you stop treating perception as reception.
It also explains why active senses keep evolving independently. Bats and toothed whales developed echolocation separately, and the convergence went all the way down to the molecular level, with the same amino acid substitutions in the prestin gene, which encodes the motor protein of cochlear outer hair cells, appearing in both lineages. Two mammal groups with no common echolocating ancestor arrived at the same mutations in the same gene to solve the same high-frequency hearing problem. That is convergence at a resolution that rarely gets demonstrated, and it belongs alongside the independent construction of camera eyes in cephalopods and vertebrates as evidence about which solutions are forced by physics. The corvid and parrot lineages that built comparable cognition from non-homologous forebrain tissue are the same argument in a different organ, and the primate and cetacean societies that arrived at cultural transmission separately are the same argument at the level of behavior, as is the macaque troop whose innovation spread without any object technology at all.
The parrots whose visual systems carry a fourth cone type and ultraviolet sensitivity and the meerkats running distributed vigilance across a group rather than inside one head are working the same tradeoff space from different corners. What varies is the probe, the medium, and the price. What stays constant is the arithmetic: information costs energy, energy is scarce, and any animal that has to buy its own photons will be ruthless about how it spends them.
That ruthlessness is visible in every parameter. Bats do not echolocate when they do not have to, going quiet in familiar roosts and relying on spatial memory. Beam width contracts when precision matters and expands when coverage does. Call rate tracks urgency. Some species abandon the sense entirely during the final approach and listen. None of that reads as a supersense being exercised. It reads as an expensive instrument being switched on for the minimum interval required, by an animal keeping careful track of the bill.
The 24-lecture Neurozoology course runs the tree of life on that accounting throughout, alongside the study of how knowledge moves between animals, the working animals whose capacities were discovered by people who needed them, and the dolphins whose sonar was put to work by navies that could not build anything comparable. The long-distance migrants whose routes depend on sensory systems nobody has fully characterized and the fish whose populations moved in ways that only made sense acoustically are the same story from different angles.
A bat pays for every millisecond of its own perception, out of pocket, in a currency it also needs for flying. Then it uses that flashlight to build a map of an area three kilometers across. The remarkable thing was never the sonar. It was the accounting.