microcosmos
The Double Life of a Fake Jellyfish
YouTube: | https://youtube.com/watch?v=w-pV078mYw0 |
Previous: | The Complicated Relationships of the Microcosmos |
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View count: | 145,258 |
Likes: | 7,686 |
Comments: | 221 |
Duration: | 10:42 |
Uploaded: | 2022-01-17 |
Last sync: | 2024-12-07 06:15 |
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Journey to the Microcosmos is a Complexly production.
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SOURCES:
https://animaldiversity.org/accounts/Hydrozoa/
https://researchwith.montclair.edu/en/publications/whos-lurking-in-your-lagoon-first-occurrence-of-the-invasive-hydr
https://www.researchgate.net/publication/226364079_Effects_of_temperature_salinity_and_predators_on_mortality_of_and_colonization_by_the_invasive_hydrozoan_Moerisia_lyonsi
https://invasions.si.edu/nemesis/species_summary/50786
https://www.researchgate.net/publication/227283396_Prey_feeding_rates_and_asexual_reproduction_rates_of_the_introduced_oligohaline_hydrozoan_Moerisia_lyonsi
Follow Journey to the Microcosmos:
Twitter: https://twitter.com/journeytomicro
Facebook: https://www.facebook.com/JourneyToMicro
Support the Microcosmos:
http://www.patreon.com/journeytomicro
More from Jam’s Germs:
Instagram: https://www.instagram.com/jam_and_germs
YouTube: https://www.youtube.com/channel/UCn4UedbiTeN96izf-CxEPbg
Hosted by Hank Green:
Twitter: https://twitter.com/hankgreen
YouTube: https://www.youtube.com/vlogbrothers
Music by Andrew Huang:
https://www.youtube.com/andrewhuang
Journey to the Microcosmos is a Complexly production.
Find out more at https://www.complexly.com
Stock video from:
https://www.videoblocks.com
SOURCES:
https://animaldiversity.org/accounts/Hydrozoa/
https://researchwith.montclair.edu/en/publications/whos-lurking-in-your-lagoon-first-occurrence-of-the-invasive-hydr
https://www.researchgate.net/publication/226364079_Effects_of_temperature_salinity_and_predators_on_mortality_of_and_colonization_by_the_invasive_hydrozoan_Moerisia_lyonsi
https://invasions.si.edu/nemesis/species_summary/50786
https://www.researchgate.net/publication/227283396_Prey_feeding_rates_and_asexual_reproduction_rates_of_the_introduced_oligohaline_hydrozoan_Moerisia_lyonsi
Thank you to Truebill for sponsoring today’s video. Truebill helps you reach your financial goals by canceling unwanted subscriptions, negotiating bills on your behalf, and budgeting.
Download Truebill for free by heading to Truebill.com/microcosmos or by clicking the link in the video description. Our master of microscopes, James, doesn’t live particularly close to the sea. But as we’ve seen in some previous episodes, that distance has not stopped him from finding ways to explore marine life.
If he can’t easily get to the sea, well, the sea can be brought to him in monthly deliveries of sand and sea water. So among all the other microbe collections in his home, James has fish tanks with no fish—just archives of those marine deliveries. And some of those tanks have been around for a while, so you might think that he’d found everything there was to find in them. But the sea is always delivering new surprises, even when it’s been firmly encased in a fish tank for more than a year. Recently, one of these old tanks turned up some surprising tentacled creatures. At first glance, James thought they might be a Journey to the Microcosmos favorite, the hydra…except hydra don’t particularly care for saltwater.
They are freshwater creatures. So naturally, James decided to take a closer look, studying his miniature creatures under the microscope. He could see rows of tentacles attached to a pod. So with this in mind, James began digging through his books on Cnidaria—the phylum that hydras belong to—and he narrowed in on a possible species: the Moerisia. That name may not mean anything to you right now. But when James saw it, it made him realize something else: somewhere in his tank, there must be a jellyfish. Now to understand why James had this realization, you need to first hear a little bit more about how the moerisia actually lives. An important part of that is that the moerisia actually has two lives. Moerisia are a type of hydrozoan, a group of cnidarians that includes about 3700 species. While they’re not as well-studied as other famous hydrozoans like the hydra or the Portuguese man-o-war, we do know that several Moerisia species likely originated in the Black Sea but have since spread widely—even found in estuaries in the United States. Their spread has probably been helped by the fact that they’re able to withstand a wide range of temperatures and salinities, making it easy for them to navigate new waters. They survive on zooplankton like our favorite crustacean, the copepod. And as we said earlier, the Moerisia has two lives.
One, as we’ve been observing, is the polyp form. And the other, is this…the medusa. Or as James named it: Squishy the Jellyfish. The double life is a common hydrozoan trait, though we should note that Hydras are a notable exception, living strictly in a polyp form. But for hydrozoans like the moerisia, things are a little more complex.
When they hatch, they emerge from an egg as a larva called a planula, which settles onto the ground and develops into a single polyp, radially symmetric and usually attached to objects like plants, shells, or rocks. And from there, the polyps begin to bud, forming more and more polyps until there’s a whole colony of them attached to each other. Within this colony, polyps can take on different forms to serve different functions. Some might take on spiny tentacles that allow them to defend the colony, while others have mouths dedicated to eating.
Still others might be dedicated strictly to reproductive function. The polyp stage is clearly distinct from the medusa stage. One looks more like a diffuse tree, while the other looks more like a bag with strings dangling off of it. But the real crux of their difference is not in their appearance, but in their reproduction. Because hydrozoans can reproduce in both stages, just very differently.
As a polyp, it reproduces asexually, budding off to form new polyps and eventually to form the medusa. You can see the polyp actually budding off to create this next stage of life, that little nub eventually expanding and releasing to create what will end up resembling an inverted polyp…or an umbrella. And unlike the sessile, anchored polyp, medusas are free-swimming. Inside its opening is an inner ring of tissue called the velum, which helps the medusa move around by tensing up and relaxing. For this Moerisia species, the medusa are phototaxic, meaning they like swimming toward light.
That’s actually how James found them in his tank. After identifying the possible species and reading that they like to swim toward light, he decided to check the side of the tank that received all the morning sunshine. When he did, he found his tiny jellies. But the main function of this form is less about light and more about sex. In Moerisia that have been raised in the lab, the medusa takes about 8 days to develop gonads. And when they do, they will proceed to their next step: sex. The exact details of how hydrozoans have sex varies with different species, and we haven’t been able to find an answer to exactly how the Moerisia do it in the literature. But we want to briefly state that one of the hydrozoan possibilities is that the male releases sperm into the water, and the female releases eggs that chemically attract the sperm to them. The fertilization is entirely external, just happening in the water, and eventually that fertilized egg will develop into a new organism. Here’s an important question though, why the double life? Why two different stages that can each reproduce in completely different ways?
Well, because asexual and sexual reproduction are both pretty nifty talents to have on hand. Asexual reproduction is fast, and it helps polyps build their local populations quickly. The downside is that an asexual polyp means limiting both the scenery and the gene pool.
With that comes the risk that the environment will shift suddenly and both the polyp and the entire population will be unable to adapt fast enough to survive. But by leading a second sexually reproductive life as a medusa, the hydrozoan gets to disperse both physically and genetically. But there is a cost—after all, sexual reproduction takes time and special organs and the hope that sperm will meet an egg. But that is why the hydrozoan doesn’t strictly rely on sexual reproduction either.
This combined strategy is part of why the Moerisia has been so successful at traveling beyond its origins. It gets the best of both worlds, as an organism that is at times static and dividing, and at other times swimming and mixing. Each generation produces a large local population that can eventually expand and spread. We should, here at the end however, admit one thing.
Technically, our Squishy the Jellyfish is not a “true” jellyfish. To be considered a true jellyfish, an animal has to be a member of the class Scyphozoa. And Scyphozoa—like the hydrozoa—are part of the Cnidarian phylum.
So while Moerisia and their fellow medusa hydrozoa do bear a strong resemblance and relationship to their true jelly relatives, they also have their own unique structures that make them distinct (and, alas, not true jellyfish). But in our tank of sea water, Squishy the Jellyfish will keep his title. He has worked and traveled a long way to earn it. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Truebill for sponsoring this video.
Still searching for a New Year’s resolution that you can actually keep? How about getting rid of a few of the streaming services that you barely remember signing up for and very often forget you even have? Or maybe just try feeling more in control of your finances in the New Year.
Either way, Truebill is there to help you out. Truebill is the all-in-one personal finance app that helps you to take control of your financial life—helping you save more and spend less. With Truebill, you securely connect your financial accounts, and they’ll take care of the rest. This personal finance manager tracks all your subscriptions in one place, cancels unwanted ones with just a tap by safely and securely identifying recurring charges.
It can even negotiate your bills for you, while also monitoring your credit score and automating your savings. And you can do all of this with just this one app. Download Truebill for free today by heading to Truebill.com/microcosmos or by clicking the link in the description There’s a bunch of names coming up on the screen right now.
They are the people who make this channel possible. They are our patrons on Patreon. They are people who saw chill, weird, interesting microscopy videos on YouTube and they were like, “I want to watch more of those.” And then they watched a few more and decided to go to Patreon.com/journeytomicro.
So, if you’re looking for someone to thank, those are the people. If you want to see more from our Master of Microscopes, James Weiss, check out Jam & Germs on Instagram or TikTok or pick up his book, The Hidden Beauty of the Microscopic World. And if you want to see more from us, there’s always a subscribe button somewhere nearby.
Download Truebill for free by heading to Truebill.com/microcosmos or by clicking the link in the video description. Our master of microscopes, James, doesn’t live particularly close to the sea. But as we’ve seen in some previous episodes, that distance has not stopped him from finding ways to explore marine life.
If he can’t easily get to the sea, well, the sea can be brought to him in monthly deliveries of sand and sea water. So among all the other microbe collections in his home, James has fish tanks with no fish—just archives of those marine deliveries. And some of those tanks have been around for a while, so you might think that he’d found everything there was to find in them. But the sea is always delivering new surprises, even when it’s been firmly encased in a fish tank for more than a year. Recently, one of these old tanks turned up some surprising tentacled creatures. At first glance, James thought they might be a Journey to the Microcosmos favorite, the hydra…except hydra don’t particularly care for saltwater.
They are freshwater creatures. So naturally, James decided to take a closer look, studying his miniature creatures under the microscope. He could see rows of tentacles attached to a pod. So with this in mind, James began digging through his books on Cnidaria—the phylum that hydras belong to—and he narrowed in on a possible species: the Moerisia. That name may not mean anything to you right now. But when James saw it, it made him realize something else: somewhere in his tank, there must be a jellyfish. Now to understand why James had this realization, you need to first hear a little bit more about how the moerisia actually lives. An important part of that is that the moerisia actually has two lives. Moerisia are a type of hydrozoan, a group of cnidarians that includes about 3700 species. While they’re not as well-studied as other famous hydrozoans like the hydra or the Portuguese man-o-war, we do know that several Moerisia species likely originated in the Black Sea but have since spread widely—even found in estuaries in the United States. Their spread has probably been helped by the fact that they’re able to withstand a wide range of temperatures and salinities, making it easy for them to navigate new waters. They survive on zooplankton like our favorite crustacean, the copepod. And as we said earlier, the Moerisia has two lives.
One, as we’ve been observing, is the polyp form. And the other, is this…the medusa. Or as James named it: Squishy the Jellyfish. The double life is a common hydrozoan trait, though we should note that Hydras are a notable exception, living strictly in a polyp form. But for hydrozoans like the moerisia, things are a little more complex.
When they hatch, they emerge from an egg as a larva called a planula, which settles onto the ground and develops into a single polyp, radially symmetric and usually attached to objects like plants, shells, or rocks. And from there, the polyps begin to bud, forming more and more polyps until there’s a whole colony of them attached to each other. Within this colony, polyps can take on different forms to serve different functions. Some might take on spiny tentacles that allow them to defend the colony, while others have mouths dedicated to eating.
Still others might be dedicated strictly to reproductive function. The polyp stage is clearly distinct from the medusa stage. One looks more like a diffuse tree, while the other looks more like a bag with strings dangling off of it. But the real crux of their difference is not in their appearance, but in their reproduction. Because hydrozoans can reproduce in both stages, just very differently.
As a polyp, it reproduces asexually, budding off to form new polyps and eventually to form the medusa. You can see the polyp actually budding off to create this next stage of life, that little nub eventually expanding and releasing to create what will end up resembling an inverted polyp…or an umbrella. And unlike the sessile, anchored polyp, medusas are free-swimming. Inside its opening is an inner ring of tissue called the velum, which helps the medusa move around by tensing up and relaxing. For this Moerisia species, the medusa are phototaxic, meaning they like swimming toward light.
That’s actually how James found them in his tank. After identifying the possible species and reading that they like to swim toward light, he decided to check the side of the tank that received all the morning sunshine. When he did, he found his tiny jellies. But the main function of this form is less about light and more about sex. In Moerisia that have been raised in the lab, the medusa takes about 8 days to develop gonads. And when they do, they will proceed to their next step: sex. The exact details of how hydrozoans have sex varies with different species, and we haven’t been able to find an answer to exactly how the Moerisia do it in the literature. But we want to briefly state that one of the hydrozoan possibilities is that the male releases sperm into the water, and the female releases eggs that chemically attract the sperm to them. The fertilization is entirely external, just happening in the water, and eventually that fertilized egg will develop into a new organism. Here’s an important question though, why the double life? Why two different stages that can each reproduce in completely different ways?
Well, because asexual and sexual reproduction are both pretty nifty talents to have on hand. Asexual reproduction is fast, and it helps polyps build their local populations quickly. The downside is that an asexual polyp means limiting both the scenery and the gene pool.
With that comes the risk that the environment will shift suddenly and both the polyp and the entire population will be unable to adapt fast enough to survive. But by leading a second sexually reproductive life as a medusa, the hydrozoan gets to disperse both physically and genetically. But there is a cost—after all, sexual reproduction takes time and special organs and the hope that sperm will meet an egg. But that is why the hydrozoan doesn’t strictly rely on sexual reproduction either.
This combined strategy is part of why the Moerisia has been so successful at traveling beyond its origins. It gets the best of both worlds, as an organism that is at times static and dividing, and at other times swimming and mixing. Each generation produces a large local population that can eventually expand and spread. We should, here at the end however, admit one thing.
Technically, our Squishy the Jellyfish is not a “true” jellyfish. To be considered a true jellyfish, an animal has to be a member of the class Scyphozoa. And Scyphozoa—like the hydrozoa—are part of the Cnidarian phylum.
So while Moerisia and their fellow medusa hydrozoa do bear a strong resemblance and relationship to their true jelly relatives, they also have their own unique structures that make them distinct (and, alas, not true jellyfish). But in our tank of sea water, Squishy the Jellyfish will keep his title. He has worked and traveled a long way to earn it. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Truebill for sponsoring this video.
Still searching for a New Year’s resolution that you can actually keep? How about getting rid of a few of the streaming services that you barely remember signing up for and very often forget you even have? Or maybe just try feeling more in control of your finances in the New Year.
Either way, Truebill is there to help you out. Truebill is the all-in-one personal finance app that helps you to take control of your financial life—helping you save more and spend less. With Truebill, you securely connect your financial accounts, and they’ll take care of the rest. This personal finance manager tracks all your subscriptions in one place, cancels unwanted ones with just a tap by safely and securely identifying recurring charges.
It can even negotiate your bills for you, while also monitoring your credit score and automating your savings. And you can do all of this with just this one app. Download Truebill for free today by heading to Truebill.com/microcosmos or by clicking the link in the description There’s a bunch of names coming up on the screen right now.
They are the people who make this channel possible. They are our patrons on Patreon. They are people who saw chill, weird, interesting microscopy videos on YouTube and they were like, “I want to watch more of those.” And then they watched a few more and decided to go to Patreon.com/journeytomicro.
So, if you’re looking for someone to thank, those are the people. If you want to see more from our Master of Microscopes, James Weiss, check out Jam & Germs on Instagram or TikTok or pick up his book, The Hidden Beauty of the Microscopic World. And if you want to see more from us, there’s always a subscribe button somewhere nearby.