Bats are not blind


The more I learn about bats, the more I am impressed at the abilities of these mammals. I had taken the phrase ‘blind as a bat’ literally and thought that bats depended entirely on echolocation to navigate. Christie Wilcox sets me straight and says that bats use both vision and echolocation to get around, using each for specific purposes.

Many bats are active at night and use a sonar-like sense (echolocation) to find their prey, which is probably where the myth that they are blind came from. But all 1,100 bat species can see just fine, and in many cases, their vision is quite good.

Rather than rely entirely on their hearing, a fascinating study published in Frontiers in Physiology in 2013 showed that even nocturnal microbats likely use a combination of vision and echolocation to “see.” The scientists from Tel Aviv University studied two bat species which, like many bats, awaken and begin to hunt just after the sun goes down. By glueing special recorders to bats, they were able to determine that the bats use echolocation regardless of light levels, dismissing the notion that they switch to sound as darkness sets in. Instead, they use it all the time, because it’s better at detecting small, moving objects. “Imagine driving down the highway: Everything is clear in the distance, but objects are a blur when you pass them,” lead author Arjan Boonman told Popular Science. “Echolocation gives bats the unique ability to home in on small objects–mostly insects–while flying at high speeds.” Their eyes, on the other hand, are key for general orientation. “We find that echolocation is better than vision for detecting small insects even in intermediate light levels,” write the authors, “while vision is advantageous for monitoring far-away landscape elements in both species.”

But in addition to setting the record straight on bat navigation systems, Wilcox also takes Neil deGrasse Tyson to task for glibly tweeting stuff about biology in general and bat vision in particular that is wrong, saying that this is not the first time that the popularizer of science has gone astray.

Many know Neil deGrasse Tyson for his pithy, humorous science tweets, which are a part of his greater science communication strategy. As of late, though, scientists have become quite vexed with NDT’s 140-character stylings, as he’s been foraying outside his planetary expertise and into biological phenomena, getting the facts wrong every time. First, there was his mistaken evaluation of evolutionary drivers and how sex works, excellently torn apart by Emily Willingham (a Ph.D. scientist whom Tyson then condescendingly called “a woman who has a blog”, prompting some to suggest he be referred to as just a “man with a twitter”). Then came his misunderstanding of genetics and deleterious alleles, which was ripped apart by Jeremy Yoder (another Ph.D. scientist).

When scientists step outside their area of expertise, they should exercise caution, especially if a lot of people listen to them. Tyson should take heed.

Comments

  1. Rob Grigjanis says

    “man with a twitter”; Twit will do.

    He also gets physics wrong, as when he tweeted one Christmas that Santa chose his lead reindeer well, since red light penetrates fog better than other wavelengths. And he repeated this nonsense in an NPR interview. Embarrassing.

  2. StevoR says

    Wilcox also takes Neil deGrasse Tyson to task for glibly tweeting stuff about biology in general and bat vision in particular that is wrong, saying that this is not the first time that the popularizer of science has gone astray.

    Neil deGrasse Tyson certainly got it wrong on Pluto too in the eyes of a lot of astronomers and others myself included and his obnoxious, snide, deliberately mean and bullying attacks on children (and adults) writing to argue against him shows that he’s really quite a douchebag at times.

    The latest findings from New Horizons on Pluto really show its an incredible active, diverse, complex and amazing little planet.

  3. Rob Grigjanis says

    StevoR @3: Don’t think you can blame Tyson for Pluto. It was the International Astronomical Union that decided that. And ‘wrong’ is rather subjective on this matter. The “clearing the neighbourhood”* dynamical parameter (whichever of the major ones you choose) makes a clear distinction between the eight planets and the dwarf planets.

    *A misnomer, some would argue, but a sound parameter anyway, IMO.

  4. StevoR says

    @ ^ Rob Grigjanis : Oh I don;t blame him for everything Pluto~wise but he’s still very wrong here and also behaved very badly and meanly and unhelpfully for astronomy.

    The orbital clearance BS criteria is BS for a lot of reasons including the fact that even Earth couldn’t clear its orbit at Pluto’s distance and conversely Pluto at Earth’s distance could. Plus if a “dwarf star” – which – includes our Sun among 90% or so of others is still a counted as star sure;y a “dwarf planet” should likewise count as a proper planet. (We don’t say dwarf trees or dogs or rabbits or people aren’t still what they are do we?) Then when you look at Pluto and see it has more moons than the entire inner solar system put together and complex atmosphere with weather and snow precipitation and erstwhile lakes and current glaciers and mountains plus so much more. Really.

    Yeah.Pluto is indeed a proper planet. And a remarkable, wonderful little one at that. And yes, NdG Tyson and the IAU got it horribly wrong and the sooner they fix their error here the better for them.

  5. Rob Grigjanis says

    StevoR @5:

    even Earth couldn’t clear its orbit at Pluto’s distance and conversely Pluto at Earth’s distance could

    From Soter’s 2006 paper (PDF);

    A prominent objection to any definition of this kind is the contention that natural objects should be defined only by their intrinsic properties (mass, shape, composition, etc.) and not by their dynamical context. But why is dynamical
    context any less relevant? We refer to objects that orbit planets as “moons”,
    although two of them are larger than the planet Mercury, and most of them (called
    irregular satellites) appear to be captured asteroids and comets. We distinguish
    meteoroids orbiting the Sun from meteorites lying on the ground. The definition
    proposed here distinguishes planets, which dynamically dominate a well-defined
    volume of orbital space, from asteroids, KBOs and ejected planetary embryos,
    which do not.

    Your objection seems to be largely sentimental.

  6. Silentbob says

    @ 5 StevoR

    … NdG Tyson and the IAU got it horribly wrong and the sooner they fix their error here the better for them.

    Yes, do people not realise what’s at stake here! We’re talking nomenclature, for God’s sake! Nomenclature!



  7. StevoR says

    @6. Rob Grigjanis : As you might expect, I strongly disagree here.

    I’m going to note that :

    1) We know of exoplanets like HD 45364.which are analogous to the Pluto-Neptune orbital system – yet much more massive :

    The inner planet has at least 3.5 times the mass of Neptune but on average is about as far from its star as Venus is from the Sun. The outer planet is more massive – it has at least 2.2 times the mass of Saturn -and is slightly closer to its star than the Earth is to the Sun.

    Source : http://kencroswell.com/HD45364.html

    Are we going to say these aren’t planets then even though their orbits clearly aren’t clear?

    2) What about the situation with Earth and Theia – the roughly Mars sized object that collided with it early on to create our Moon. Was Earth a planet pre-collision course, suddenly a non-planet when Theia was about to hit it then a planet again post impact? Does that really make sense? What about in a future solar system where Earth might face a collision with Mercury or Venus or Mars?

    Source : http://www.space.com/6824-long-shot-planet-hit-earth-distant-future.html

    Would Earth and the other planet in collision stop being planets simply because they were on collision courses or had unclear orbits? Course not – shows how ridiculous the clear orbit criterion is!

    3) Dwarf planets and dwarf stars -most stars including our sun are dwarfs, why shouldn’t we accept that most planets are also dwarf planets – but that doesn’t stop them from actually being and counting as planets no matter how small just as it doesn’t with stars. Does X (plant,animal, person) stop being a plant,animal or person just because its of the dwarf variety? Terminology should be consistent and so logically either we stop classifying our sun and 90% of all stars which are mostly core hydrogen fusing main-sequence stars as proper stars – including even “dwarf” O type behemoths such as Mintaka A (Delta Orionis A) which has twenty times our daytime stars mass and is 90,000 times as bright* – or we admit that dwarf planets also fully count as planets too.

    Oh & I’d be interested to see if you get these questions Ken Croswell asks here :

    http://kencroswell.com/PlutoQuestion2.html

    (Link to the first one from there.)

    Food for thought and examples of why the case for Pluto and the ice dwarf is actually a logically compelling one.

    * Source : Kaler’s Stars website – Mintaka page.

  8. Rob Grigjanis says

    StevoR @8:

    (1) & (2): You’re being pedantic. Margot, 2015:

    What the IAU intended is not the impossible standard of impeccable orbit clearing; rather the standard is analogous to what Soter (2006, 2008) described as a dynamical-dominance criterion.

    The criterion is the ability of the body to scatter much smaller bodies, either to very large distances, or at least some distance beyond its Hill radius (region of its gravitational dominance), over the main sequence lifetime of the host star. The resulting parameter (discriminant) clearly distinguishes between the eight planets and other known bodies. With value greater than one identifying a body which could clear its orbit of small bodies in the sun’s lifetime*, the smallest (Margot) value among the eight is Mars’ 54 (Jupiter is 40,000, Earth is 810). The values for Ceres and Pluto are 0.04 and 0.028 respectively.

    (3) That’s just silly. The use of the word ‘dwarf’ is completely unrelated in the cases of stars and planets. Apples and oranges.

    *It shouldn’t be necessary to point out that this does not include small objects around the L4 and L5 Lagrange points, since these orbit with the planet.

  9. Rob Grigjanis says

    Oh & I’d be interested to see if you get these questions Ken Croswell asks here

    Yeah, I got them right, but WTF does that have to do with the topic? Pluto ‘defenders’ really are a silly bunch, kinda like Creationists with their puerile attempts at ‘gotcha’ questions. Surely you can love the little guy no matter what his designation!

  10. StevoR says

    @ ^ Rob Grigjanis : I think those questions add some interesting perspective on how planetary Pluto really is and note that you haven’t actually addressed the other points I raised above showing why the orbital clearance criterion is illogical and a very bad one to use in defining what counts as a planet. I’ll admit I’m surprised you got them right, I don’t think that most people would do so!

    I’ll also add that there are thought to be “rogue” planets which wander the galaxy – or even intergalactic space – unattached to any star – how then do we determine if their orbits are “clear” or not?

    See :

    http://www.space.com/11699-rogue-alien-planets-milky-common.html

    among other places.

  11. StevoR says

    @9. Rob Grigjanis : D’oh just seen your up thread comment, above your later one. Okay,sorry, you did attempt to address the points raised in my #8.

    (1) & (2): You’re being pedantic. Margot, 2015:
    What the IAU intended is not the impossible standard of impeccable orbit clearing; rather the standard is analogous to what Soter (2006, 2008) described as a dynamical-dominance criterion.

    Oh I think its a lot more than mere pedantry. I also think Soter’s dynamical dominance thing is a metaphorical epicycle and an ad hoc later and I’d say failed attempt to salvage the unsalvagable issues I noted in points 1 & 2 there. How exactly does it refute either the exoplanetary Neptune-Pluto analogue(s) or situation with colliding planets? I don’t believe it does actually address either case.

    (3) That’s just silly. The use of the word ‘dwarf’ is completely unrelated in the cases of stars and planets. Apples and oranges.

    Are both counted as fruit. So are cherries, blackberries and grapes despite them being much smaller.

    I don’t think it is unrelated when we are talking about types of astronomical objects and I don’t think its “silly” at all to point out the inconsistency here – quite the reverse it would be silly to say one category of dwarf isn’t a real X whilst the other is a real X.

  12. Rob Grigjanis says

    StevoR @11:

    how planetary Pluto really is

    You’re assuming what ‘planetary’ means. Naughty. Is Eris a planet? How about Makemake? If so, why? Give your unambiguous definition of ‘planet’.

    you haven’t actually addressed the other points I raised above showing why the orbital clearance criterion is illogical

    Yes I did, quite clearly I thought. Maybe you didn’t understand, or you just didn’t read. The point of the definition is not that orbits have been cleared. The point is that the dynamic properties (mass, mass of star, orbit radius) give the bodies the ability to clear their neighbourhoods of much smaller objects. Have you looked at any of the papers I linked to? What specifically do you think is illogical about them?

    I’m surprised you got them right

    I’ve been an astronomy buff since age seven. All you need is a rough idea of the distances, sizes and albedos of the various bodies. And my physics training since then gives me an appreciation of the arguments I’ve linked to.

    there are thought to be “rogue” planets which wander the galaxy

    You haven’t even looked at the work of Soter, Margot, etc, have you? They consider bodies in orbit around stars. Rogues’ only ‘orbit’ would be around the galactic core, I guess. And the designation ‘rogue planet’ distinguishes them from ‘planet’ and ‘dwarf planet’.

  13. Rob Grigjanis says

    I also think Soter’s dynamical dominance thing is a metaphorical epicycle and an ad hoc later and I’d say failed attempt to salvage the unsalvagable issues I noted in points 1 & 2 there.

    Nonsense. Do you think the astronomers who drafted the criteria were drunk, or had otherwise somehow forgotten that not all orbits are, or always have been, actually clear? The only mistake they made was using wording that could be abused by nitpickers. Another way of putting it is “planets have elbows”, and the theory behind that is sound.

  14. StevoR says

    @ ^ Rob Grigjanis : Planets have elbows?!

    No they don’t.

    You’re assuming what ‘planetary’ means. (1) Naughty. Is Eris a planet? How about Makemake? (2) If so, why? Give your unambiguous definition of ‘planet’. (3)

    Bracketed numbers added for ease of reference.

    My personal preferred definition of planet? Well its an astronomical body that :

    I) is never capable of being self-luminous via core nuclear fusion thus not a star or brown dwarf or stellar remnant.

    II) Is gravitationally rounded or elliptical in the case of rapid enough spin by its own mass and thus not a comet or asteroid.

    III) Does not directly orbit another planet and therefore is not a moon.

    I think that’s a pretty clear, simple and easily determined definition which works pretty well – certainly much better than the erroneous IAU one which violates Occam’s razor and the Copernican principle (did you know that specifies that “planets” must only orbit our daytime star out of all the ___________ns of stars in our cosmos?) as well as failing the reductio ad absurdum test as pointed out in the first few points of my #8 .

    2) Yes in both cases and also yes for many others. Ceres is also a planet I think as are Sedna, Quaoar, Varuna and many more. Oh & no, I don’t expect schoolkids to memorise every one of those ice dwarfs but knowing that they are out there and also count as planets – yeah.

    1) Er, disputing and claiming an alternative definition more than “assuming”. that’s kinda the whole topic of debate here. You OTOH seem to assume the IAU got it right which would be an incorrect assumption on your part here.

  15. Rob Grigjanis says

    StevoR: Well, you’ve established that you haven’t actually read the papers I linked to.

    You OTOH seem to assume the IAU got it right which would be an incorrect assumption on your part here.

    No, it’s not ‘right’ or ‘wrong’. It’s a theoretically sound criterion for classifying certain objects. What’s ‘wrong’ is your emotional response to that classification, and your misuse of ‘Occam’s razor’, and ‘reductio ad absurdum‘. What would really be absurd would be continuing this exchange.

  16. StevoR says

    @ ^ Rob Grigjanis : Misuse how exactly?

    And no, the IAU definition ain’t sound and seems you can’t defend it and are choosing to run away instead.

    @#15 :“II) Is gravitationally rounded or elliptical in the case of rapid enough spin by its own mass and thus not a comet or asteroid”

    Yeah I’m thinking Haumea among others* here :

    http://apod.nasa.gov/apod/ap080923.html

    Egg shaped /elliptical , same diff just as with stars.***

    Yegods it’d be awesome to send a spacecraft to see Haumea up close – as well as Eris and Sedna and others. If only controlled NASA’s budget or were POTUS .. Sigh. Y’know how much serendipity and exploration rocks right? Well, maybe you don’t I guess. But it sure flippin’ does. We can learn so much if we go out and actually look. But, as I grok it, less than 1/2 of 1% is all NASA gets. Far too little. Priorities – they’d be all fouled up.

    * Y’know Jove and Saturn aren’t exactly round right? Nor even is Earth although our pale blue dot is a lot closer to it.

    *** Like Achernar, Regulus & Altair among others – again see Ken Croswell’s website archives among other places.

  17. Rob Grigjanis says

    StevoR: Once more unto the breach…

    Misuse how exactly?

    For a start, your reductio ad absurdum is actually a non sequitur. Your examples are irrelevant.

    And no, the IAU definition ain’t sound and seems you can’t defend it and are choosing to run away instead.

    I’ve said all that needs to be said, but you don’t seem to understand, as you keep repeating the nonsense I’ve already answered. Maybe if you learned a little celestial mechanics…

    Y’know Jove and Saturn aren’t exactly round right? Nor even is Earth although our pale blue dot is a lot closer to it [nor even is Mars].

    Yeah, since I was about ten. Mind you, it wasn’t until a decade or so later (so about 40 years ago) that I came across notions like reference ellipsoids and geoids.

  18. Rob Grigjanis says

    StevoR: Since it was irrelevant to the topic at hand, I’d ignored it, but I just looked at your link to Croswell’s article on HD 45364. It’s embarrassing;

    Indeed, it was Pluto’s failure to clear its orbital zone of other material–for example, of Neptune…

    Croswell doesn’t seem to understand that the Solar System, like us, lives in 3D space, not 2D. Pluto has an inclination to the ecliptic of 17 degrees. Just because Pluto can be closer to the Sun than Neptune doesn’t mean that they get anywhere close to each other. In fact, when Pluto is at the same distance to the Sun as Neptune, it is about 8 astronomical units away from Neptune. That’s about 10 times the radius of Neptune’s Hill sphere! They are not anywhere near each others orbital zones.

  19. Rob Grigjanis says

    #20:

    when Pluto is at the same distance to the Sun as Neptune, it is about 8 astronomical units away from Neptune.

    Correction: That’s the closest approach to Neptune’s orbit. The closest it gets to Neptune is about 18 AU.

  20. Silentbob says

    @ Rob Grigjanis

    StevoR has been making this exact same argument — and I mean this exact same argument — since at least 2008. Every time people make the same rational points as you’re making, every time he loses the argument spectacularly, and then he just makes the same arguments next time as though nothing ever happened.

    It’s the same as his obsession with Israel. You’ve noticed that right? He makes the same special pleading, sentimental arguments for Israeli exceptionalism every single time, gets shot down every single time, and then starts over again with the same arguments from scratch next time.

    I tell you from experience, you’re arguing with a broken record.

  21. StevoR says

    @ ^ Silentbob : Well, yes, these are arguments I’ve been making consistently for some time however I’d strongly dispute that I’ve actually lost any of the arguments here – quite the reverse in reality. You disagree with me consistently but that’s your subjective – and incorrect opinion.

    @ 19,20, 21, Rob Grigjanis :

    For a start, your reductio ad absurdum is actually a non sequitur. Your examples are irrelevant.

    That’s your erroneous asertion which has no logic or supporting evidence to support it. How is it a non-sequiteur precisely? When the definition of “planet” depends on having a clear orbit and there are circumstances such as those listed in #8 & #11 where planets clearly won’t have clear orbits but are nonetheless planets and it would be ridiculous to say otherwise -which it is – then its very relevant and applicable and the IAU definition fails the reductio ad absurdum logical test in leading to clearly ridiculous results.

    I’ve said all that needs to be said, but you don’t seem to understand, as you keep repeating the nonsense I’ve already answered. Maybe if you learned a little celestial mechanics…

    I have and what I’ve said isn’t “nonsense” at all as I’ve shown and supported with, y’know, all that evidence, reasoning and cites as opposed to mere assertions.

    I just looked at your link to Croswell’s article on HD 45364. It’s embarrassing; Croswell doesn’t seem to understand that the Solar System, like us, lives in 3D space, not 2D. Pluto has an inclination to the ecliptic of 17 degrees. Just because Pluto can be closer to the Sun than Neptune doesn’t mean that they get anywhere close to each other. In fact, when Pluto is at the same distance to the Sun as Neptune, it is about 8 astronomical units away from Neptune. That’s about 10 times the radius of Neptune’s Hill sphere! They are not anywhere near each others orbital zones.

    Yet their orbits cross and therefore aren’t clear – as well as things like trojans etc ..and the same applies – at least in terms of crossing orbits to the exoplanets of HD 45364, HD 82943 and HD 128311. When orbits areoverlapping and intersecting as they are in all these cases, you cannot say that they are really “clear”- a term which as noted requires extra clarification and thus fails Occam’s Razor by raising unnecessary complications. Saying “oh we mean “clear” by this particular arguable and dubious definition of “clear” with this special pleading that things are in resonance or needing Hill spheres, or objects of X mass don’t really count for special pleading reasons, etc ..is just adding needless metaphorical “epicycles” to a definition that has failed the test of logic.

    Incidentally, the IAU definition also fails the test of the Copernican principle and even common usage in ruling that all planets must only orbit our star – yes I kid you not there – which again, is clearly absurd and good reason for the IAU definition to be scrapped and a superior alternative adopted instead.

  22. Rob Grigjanis says

    StevoR @23:

    Yet their orbits cross and therefore aren’t clear

    Their orbits are 8 AU apart when they are equidistant from the sun. How is this ‘crossing’? And because they are in a 3:2 orbital resonance, they can never come closer to each other than about 18 AU. Therefore their respective orbital zones never intersect.

    Of the eight IAU planets, Neptune has the most cluttered orbital zone, yet Neptune accounts for 99.996% of the mass in it zone. Pluto accounts for only 8% of the mass in its zone, Ceres a whopping 33%! You see the distinction? Like it or not, there are two different classes of bodies here. What you choose to call them, I don’t really care, but refusing to recognize the clear physical difference, and the necessity of some sort of nomenclature change, is just blinkered ignorance. Occam’s razor does not mean “ignore differences to make life simpler”.

    When the definition of “planet” depends on having a clear orbit…

    This is what I mean by pedantry. You seriously think that the drafters of the criteria forgot about near-Earth objects, or Jupiter’s trojans?

    Saying “oh we mean “clear” by this particular arguable and dubious definition of “clear” with this special pleading that things are in resonance or needing Hill spheres, or objects of X mass don’t really count for special pleading reasons, etc ..is just adding needless metaphorical “epicycles” to a definition that has failed the test of logic.

    No, it means clarifying short sentences drafted for public consumption. By the way, “special pleading that things are in resonance or needing Hill spheres” is fucking hilarious. Yeah, who needs to understand orbital dynamics when talking about, er, things that are orbiting? Not you, certainly.

    Incidentally, the IAU definition also fails the test of the Copernican principle and even common usage in ruling that all planets must only orbit our star

    Yes, and changing “is in orbit around the Sun” to “is in orbit around one or more stars or stellar remnants” is just another metaphorical epicycle! Definitions must never be modified!

    Your latest blast of obtuseness has taken me well past my recommended monthly intake, so I will now ‘run away’ from your laser-like logic. It’s been a slice.

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