Why These Moths Don’t Run Away from Bats

Why These Moths Don’t Run Away from Bats


Thanks to Brilliant for supporting this episode
of SciShow. Go to Brilliant.org/SciShow to learn more
about gifting a Brilliant Premium subscription this month. [♪ INTRO ] Being attacked by a predator can be scary,
but a new study in the journal Frontiers in Ecology and Evolution helps us understand
how some animals can keep cool under even that most extreme pressure. Even weirder, it turns out we can gain insight
into how an animal would behave, even if we can’t watch it doing the thing. Some animals are… yucky. They contain chemicals that make them toxic,
nasty-tasting, or otherwise unpleasant to be around, which is a great defense against
predators. It’s so reliable that many of these animals
are aposematic, meaning they have bright colors or other signals that warn predators to keep
away. They don’t hide, they advertise. Aposematic animals tend to be relatively sluggish
in their day-to-day movements. After all, there’s no need to rush if most
predators won’t mess with you. But being under direct attack from a predator
is a different story. This study aimed to find out if animals with
chemical defenses are able to remain relaxed under predatory pressure. To do so, the researchers tracked the behavior
of 5 different species of tiger moths. These moths have a remarkable ability to detect
the echolocation of predatory bats. If a moth hears a bat coming, it can take
evasive maneuvers by spiraling or diving out of the way. But this comes with a cost: quick, panicky
flight can make it easier to get yourself lost, get stuck on a spider web, or draw the
attention of other predators, not to mention just uses their energy. So if a moth has another line of defense — say,
chemical grossness — it may be best for them to stay relaxed when attacked. To observe the moths’ behavior, the researchers
released a bunch of moths in an outdoor arena where bats were known to hunt. Over three years, they observed more than
300 bat-moth interactions. Each time a moth was caught, the researchers
observed whether the bat ate them or spat them back out. This data let them grade the moths on a spectrum
of palatability, or tastiness. The researchers also observed whether the
moths tried to avoid the bats, or whether they just kept flying pretty normally under
attack. That let them rank the moths according to
nonchalance. They found that the less palatable species
were also cooler under pressure. It seems those chemical defenses allow the
moths to save energy on evasive maneuvers. This is pretty exciting because it means we
might be able to predict animals’ behavior from chemical traits. Researchers could study a bug in a lab, or
even a museum specimen, and based on its chemical makeup, predict how it would act to avoid
predators. This is not only much easier than observing
bugs under attack, but it could be done for rare or even extinct species. And it’s not just tiger moths that do this. Similar bat-avoiding behavior is seen in many
species of beetles, mantises, lacewings, and other moths and butterflies. These findings could open up a whole new way
to study aerial predator-prey interactions. And while those researchers were exploring
ecological dynamics in the air, another group of scientists have presented findings on the
importance of microbial ecosystems beneath the soil. Soil is obviously super important for life. It not only provides a home for lots of living
things, but also contains the nutrients necessary for plants and other organisms to thrive. A new study in the journal PNAS sheds new
light on the ways bacteria are responsible for creating that life-giving soil. Soil is more than mere dirt. It’s a mixture of minerals, water, air,
and organic matter, both alive and dead. Beneath all that life-rich soil is a subsoil
made of crumbly rocks, and beneath that is tough bedrock. Soil contains minerals that life needs — things
like phosphorus and potassium. Those are generally thought to come from down
in the bedrock. But plant roots and wind erosion can only
break down rocks near the surface, and bedrock can be several meters down. So these scientists set out to explore how
microbes deep underground might contribute to the breakdown of bedrock. To do so, they drilled a bunch of core samples
from the soil and bedrock at the Luquillo Critical Zone Observatory in Puerto Rico. They ground up samples of the bedrock, added
soil bacteria to some of the samples, and then let all of the samples sit in the lab
for 864 days. After this extensive waiting period, they
observed that the rocks had experienced some chemical breakdown, but only if the bacteria
were present. What’s more, the bacteria had increased
in abundance. Despite being in a dark room with no organic
food sources, they were thriving. The bacteria in question are chemolithotrophs,
meaning they get their energy through chemical reactions with inorganic materials in their
environment. Basically, they can feed on rocks. Genetic analysis of these soil bacteria found
that they produce special proteins on their cell surface that allow them to swipe electrons
from the iron in certain minerals, using those electrons to power their own metabolism. In the process, they accelerate the chemical
weathering of the rock, breaking it down and releasing all those wonderful nutrients that
become part of the soil. There are still some open questions. For example, we don’t how quickly this bacterial
weathering occurs in nature, or how this microbial action varies at different levels of soil. But one thing is clear: these bacteria are
a major player in the breakdown of rocks, meaning we have them to thank for the abundance
of minerals in soil that help give life to the organisms on the surface. It takes a long time to degrade bedrock into
soil, but the time for holiday shopping is almost up. One quick way to check someone off your list
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100 thoughts on “Why These Moths Don’t Run Away from Bats

  1. But the bible claims "all living things shall be food for you". I guess that claim was wrong as hundreds of living things will kill us deader than dead.

  2. Thanks to Brilliant for supporting this episode of SciShow. Go to Brilliant.org/SciShow to learn more about gifting a Brilliant Premium subscription this month.

  3. These soil studies might prove invaluable for all that space colonization I keep hearing about. If we're going to try creating a sustainable, livable environment either in orbit or on the surface of Mars, having a comprehensive knowledge base about the foundational biology is going to radically improve the chances of success.

  4. Just saying. There was a video that was posted just earlier about evolution and I thought that it was a christmas gift but then they deleted it…

  5. What did you guys do with the video about hyperspeed evolving animals? It says it's private, yet I have it my notifications list.

  6. I walked up to a skunk once, it acted like I wasn’t even there until I got maybe 6ft from it and finally gave me a warning hiss.

  7. Hay scishow, why did I get a notification for "things that rapidly evolve because of us" or something of that nature…to be brought to a screen that said private video…explanation???

  8. This makes me want to make a "Oh, you're approaching me?" meme with the poisonous moth and a bat, but I don't know which to make Dio and which to make Jotaro.

  9. hey, lets toss some bedrock eating microbes on Mars n wait a couple years to plant stuff!👀 Its not like the atmosphere would be much of a survival factor for them underground.

  10. Wow. I didn't know poisonus animals in general were sluggish. That does remind me of skunks. They are notorious for thier defenses. They have a stark black and white pattern as a warning. It is about as vivid as mammal fur can get. Skunks are very sluggish. They just waddle around and take thier sweet time. They don't need to be fast. One time I was taking a walk in the evening. I accindly approached a skunk. When I saw it, I just turned around and ran away. I didn't want to take my chances. Any preditor would do the same, unless they were really stupid. The one exception is the great horned owl, which is immune to skunk. There is something interesting I learned by seeing skunks in person. Skunks actually smell fine most of the time. It is just when they feel threatened they make a stink.

  11. If there are rock eating bacteria, are there also bacteria that can turn the nutrient poor sand or soil of a wasteland into a nutrient rich soil you can actually grow things in?

  12. I like your work, overall. So I feel comfortable to give you some critique: as a researcher it really makes me cringe when you don't name the researchers' names and affiliations and funding sources, but the journal that contributed nothing to the study.
    If you give credit, give it where it's due.

  13. so, being under less evolutionary pressure to evolve evasive behaviour due to previous acquisition of other defense mechanisms results in evolving less evasive bahaviour/loosing such behaviour? how wonderfully surprising, grant money well spent.

  14. The moth on your thumbnail is the wrong kind of moth. Tiger moths are big and fuzzy. What you’ve got are the evil little moths that eat wool and are their own separate clade.

  15. So what I wanna know is….. HOW?!?! How did scientists track all these bat-moth interactions?? Night vision goggles, I can get that far, but how on earth did they manage to track itty tiny things flyin' around all night? I can barely manage to watch a bird in broad daylight! I mean, I'm also not a bird watching professional but still…

    Also, getting a good giggle from all the Minecraft related comments 😀

  16. Donald Trump is aposomatic. the urine yellow neon glow warns predators that he is so disgusting that you will not be able to even take a bite of him without getting nauseous

  17. How would the bat know this particular moth tastes bad before it kills it. What advertises that in the dark?
    Where I am, the "yucky" moths are active only during the day whilst all the bats are roosting

  18. You guys have done videos about sleep/dreaming, any chance we can get a video about sleep paralysis? Because it (moreso the horrifying hallucinations) sucks and not even my therapist knew it existed.

  19. A SciShow on refrigerant from fridges or AC units would be great. Things like that refrigerants are a heavy gas and how to tell if there is a leak

  20. All I could think of is chemolithitrophs desiring to see the world beyond their bedrock oasis. Tiny little rockets being sent up in the dirt to explore the inhospitable wastelands beyond the rock.

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