Learn about the record-breaking glowing kitefin shark; cities’ unique microbiomes; and the true origin of the Milky Way. Dive deeper into all your favorite Shark Week shows with Shark Week’s Daily Bite Podcast hosted by Luke Tipple: Listen on Apple Podcasts: https://podcasts.apple.com/us/podcast/shark-weeks-daily-bite/id1527053422 Listen on Spotify: https://open.spotify.com/show/0dfzM1ktSB1mSKD5z4Qujm?si=R8rNBksMRS-JrgMs9JIJ5g&dl_branch=1 Learn more: https://www.discovery.com/shark-week/everything-you-need-to-know-about-the-daily-bite-podcast We just found the largest glowing shark species in the world by Grant Currin Starr, M. (2021). We Just Found The Largest Luminous Glowing Shark Species in The World. ScienceAlert. https://www.sciencealert.com/three-new-luminous-glowing-sharks-have-been-found-living-in-the-ocean-s-dark-depths Mallefet, J., Stevens, D. W., & Duchatelet, L. (2021). Bioluminescence of the Largest Luminous Vertebrate, the Kitefin Shark, Dalatias licha: First Insights and Comparative Aspects. Frontiers in Marine Science, 8. https://doi.org/10.3389/fmars.2021.633582 Fox, A. (2021, March 5). Nearly Six-Foot-Long Glowing Shark Discovered in Deep Sea Off New Zealand. Smithsonian Magazine; Smithsonian Magazine. https://www.smithsonianmag.com/smart-news/nearly-six-foot-glowing-shark-discovered-deep-sea-new-zealand-180977163/ Largest Glowing Shark Species Discovered Near New Zealand. (2021). The New York Times. https://www.nytimes.com/2021/03/05/science/biggest-glowing-shark.html Different cities have different microbial fingerprints by Grant Currin Danko, D., Bezdan, D., Afshin, E. E., Ahsanuddin, S., Bhattacharya, C., Butler, D. J., Chng, K. R., Donnellan, D., Hecht, J., Jackson, K., Kuchin, K., Karasikov, M., Lyons, A., Mak, L., Meleshko, D., Mustafa, H., Mutai, B., Neches, R. Y., Ng, A., & Nikolayeva, O. (2021). A global metagenomic map of urban microbiomes and antimicrobial resistance. Cell. https://doi.org/10.1016/j.cell.2021.05.002 Coxworth, B. (2021, May 28). Study determines that each city has its own microbial signature. New Atlas. https://newatlas.com/science/cities-microbiome-signature/ Yarlagadda, T. (2021, May 27). Scientists reveal a global map that could help us track the next deadly pathogen. Inverse; Inverse. https://www.inverse.com/science/city-microbial-census See which microbe species were found in your area: http://metasub.org/map/ See which antibiotic-resistant bacteria were found in your area: https://resistanceopen.org/ The Milky Way probably didn't form from a collision like we thought by Briana Brownell Milky Way not unusual, astronomers find. (2021). EurekAlert! https://www.eurekalert.org/pub_releases/2021-05/acoe-mwn052021.php Scott, N., van de Sande, J., Sharma, S., Bland-Hawthorn, J., Freeman, K., Gerhard, O., Hayden, M. R., & McDermid, R. (2021). Identification of an [α/Fe]—Enhanced Thick Disk Component in an Edge-on Milky Way Analog. The Astrophysical Journal Letters, 913(1), L11. https://doi.org/10.3847/2041-8213/abfc57 https://www.ctvnews.ca/sci-tech/everything-we-thought-we-knew-about-our-galaxy-s-origin-might-be-wrong-1.5443661 Follow Curiosity Daily on your favorite podcast app to learn something new every day withCody Gough andAshley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Learn about the record-breaking glowing kitefin shark; cities’ unique microbiomes; and the true origin of the Milky Way.
Dive deeper into all your favorite Shark Week shows with Shark Week’s Daily Bite Podcast hosted by Luke Tipple:
We just found the largest glowing shark species in the world by Grant Currin
Different cities have different microbial fingerprints by Grant Currin
The Milky Way probably didn't form from a collision like we thought by Briana Brownell
Follow Curiosity Daily on your favorite podcast app to learn something new every day with Cody Gough and Ashley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/glowing-sharks-cities-unique-microbes-milky-way-mistake
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about how we just found the largest glowing shark species in the world; new research showing that cities have their own unique microbiomes; and why the Milky Way probably didn’t form from a collision like we thought.
CODY: Let’s satisfy some curiosity.
Researchers trawling the twilight zone off the coast of New Zealand recently pulled some surprises out of the deep blue sea. Among their finds: three species of shark that, surprisingly, were glowing. One of them is the largest bioluminescent vertebrate known to science!
The researchers were tagging along with another team as it conducted an annual survey of hoki, a whitefish that ends up as filet-o-fish sandwiches and fish fingers. But the researchers weren’t interested in the prey that came up in the nets — they were after the predators caught by accident.
When the hoki researchers pulled up a sample, the shark researchers inspected it for, well, sharks. When they found one, the scientists quickly transferred it to a dark, cold tank before taking its pictures and then, sadly, euthanizing it before collecting tissue samples.
The researchers didn’t discover any new species of sharks. Instead, they learned more about sharks that were already known to science. Three species — the kitefin shark, the blackbelly lanternshark, and the southern lanternshark — glowed with a soft, beautiful blue light.
Bioluminescence isn’t all that unusual in living things, or even in sharks specifically. But until that moment, these particular sharks had never been confirmed to glow. Even cooler, sharks use a completely different method for bioluminescence. The nervous system controls the epidermal lightshow in most animals, but sharks use hormones to pull the strings. Chemical tests on the tissue samples revealed that in these species, it’s melatonin that activates bioluminescence. If that sounds familiar, it’s because the human body uses the same hormone to fall asleep. The researchers say other hormones turn off the glow and still others likely regulate other aspects of the biological process. They’re not sure what controls the hormones themselves, though.
They’re also not quite sure why the sharks glow at all. One theory is that it helps the deep-sea creatures blend into their environment — when seen from below. The sharks found in the survey have more bioluminescent organs on their bellies. That might make them cast less of a dark silhouette against the bright background of the water’s surface. The extra light might also help them find food by illuminating the sea below them. And the nice lighting might help them reproduce by drawing attention to their private parts, too.
The researchers’ biggest find was the kitefin shark. They can grow as long as a fully grown human. That makes these residents of the twilight zone the largest bioluminescent vertebrate ever discovered, on land or in the sea.
Researchers have just revealed the findings of a humongous study of microbes in 60 cities across the world. They found more than 10,000 types of viruses and bacteria, and most of them were unique to particular regions or even specific cities. It turns out that just like people, cities have their own unique microbiomes. And knowing more about them can help scientists keep everyone healthy.
The project was a truly global endeavor. It got its start back in 2013 when a team of researchers in New York took to the subway, swabs in hand, to take a census of the microbes that were living down there. The study got microbe scientists across the world so excited that they started sending in carefully collected samples from their own cities.
Over the course of three years, researchers on six continents collected nearly 5,000 samples in public transit systems and hospitals. They found that nearly all the samples contained the same core set of 31 species of microbes. But those 31 bugs are just a tiny slice of the microbial diversity revealed in the analysis. What kind of diversity are we talking? Well, one of the researchers said he could analyze a shoe and say which city its owner had come from — with 90 percent accuracy!
In their study, the researchers found more than 4,000 species of virus and bacteria that had already been discovered. But they also found more than 700 species of bacteria and 11,000 viruses that were previously unknown to science!
Is that... bad? It’s sort of a good news-bad news situation. Sure, germs have a bad rap, but most microbes are harmless. So the numbers themselves aren’t necessarily a bad sign. Unfortunately, the study did find unnerving levels of antibiotic-resistant bacteria that could be a problem. It’s not a huge surprise given that the samples came from public transit and hospitals, but it’s indicative of a major problem. You can actually see which microbes were found in your area — both the full microbiome and the antibiotic-resistant bugs — using the interactive maps provided by the project. Check the show notes for some links!
Gross as it may be, research like this is important because it may lead to surveillance programs that would let researchers keep tabs on dangerous microbes. That might help us manage future pandemics, which we all can agree would be worthwhile.
Everybody likes to think they’re special — and that extends to the galaxy we live in. Scientists have long believed that the Milky Way formed out of a giant collision. Hardcore! Not like those other boring galaxies! Well, I’ve got some news. New research from a team of Australian astronomers suggests that the formation of our galaxy is a lot less dramatic than we thought.
Our Milky Way is a spiral galaxy, and it has a few peculiar characteristics. It’s composed of two discs. The thick disk contains older stars and the thin disc, much younger stars. Because of those age differences, scientists thought each disc might have once been a separate galaxy — and that sometime in the distant past, they smashed into each other.
But that theory is being put into question, thanks to a special twin to our Milky Way galaxy 320 million light years away that has very similar characteristics. Scientists call it UGC 10738. Okay, not exactly a catchy name.
Anyhow, this twin galaxy has a special aspect: its orientation. The galaxy is exactly lined up so we can see it edge-on. That meant that the scientists could treat it like a cross-section and take measurements of the thin, younger disc and the thick, older disc to see what elements they contained.
The important parts of the measurements are the concentrations of metals. Younger, thin disc stars, like our sun, have more metal than the older, thick disc stars. By looking at the spectrum of each disc, scientists could figure out how much metal they contained. Turns out, they’re just like our galaxy.
If our galaxy was formed in a rare and special way — like a violent collision — we wouldn’t expect to see other nearby galaxies that had the same characteristics. But we found one right in our neck of the woods.
So, instead of a violent collision between two smaller galaxies, the findings suggest that our galaxy formed by a much more gradual process: clouds of stars in space eventually colliding and methodically growing until after many millions of years, they formed the galaxy we find ourselves in now.
It might seem like a let down from the exciting origin story we previously thought. But actually, when it comes to galaxies, boring is a blessing. If our galaxy’s characteristics are commonplace, that means we can use it as an example of what’s typical — and make astronomical observations much closer to home that can be generalized to galaxies far, far away.
Let’s do a quick recap of what we learned today
[ad lib optional]
ASHLEY: Today’s writers were Grant Currin and Briana Brownell.
CODY: Our managing editor is Ashley Hamer.
ASHLEY: Our producer and audio editor is Cody Gough.
CODY: You can be like a kitefin shark by leaving us a GLOWING 5-star review on Apple Podcasts! And you can be UNLIKE the Milky Way by colliding with us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!