Recent research shows that jellyfish share surprising similarities with humans, including a sleep pattern of approximately eight hours a day, complemented by short naps. Understanding the sleep behaviors of these marine creatures can shed light on the evolutionary significance of sleep.
“Interestingly, like humans, jellyfish spend about a third of their time sleeping,” states Lior Appelbaum from Bar-Ilan University in Israel.
In animals with brains, such as mammals, sleep is crucial for memory consolidation and the elimination of metabolic waste. However, it remains unclear why sleep evolved in jellyfish, which belong to the brainless cnidarian group and possess neurons arranged in simple networks.
Appelbaum and his team utilized high-resolution cameras to observe Cassiopeia Andromeda, an upside-down jellyfish, in a controlled aquarium environment. The jellyfish were subjected to cycles of light and darkness to replicate natural conditions.
During the simulated daytime, the jellyfish exhibited an average pulse rate of over 37 times per minute, demonstrating responsiveness to sudden stimuli. In contrast, their pulse rate decreased at night, and they became less reactive, indicating a sleep state. These pulsations are vital for nutrient distribution and oxygen supply within the jellyfish’s body, as explained by Appelbaum.
Overall, jellyfish typically sleep for about eight hours each night, interspersed with brief naps lasting one to two hours. Prior studies had confirmed nocturnal sleep in C. Andromeda, but the intricacies of their sleep cycles were previously unknown.
In another experiment, researchers simulated sleep disruption by pulsating water against the jellyfish, which led to even better sleep the following day. “It mirrors human behavior: when sleep-deprived at night, we tend to feel more fatigued during the day,” notes Appelbaum.
Crucially, further examination indicated that sleep in C. Andromeda is associated with reduced DNA damage. Sleep likely protects neurons from deterioration that might occur during wakefulness, as corroborated by the observation that exposing jellyfish to ultraviolet light—thereby increasing DNA damage—resulted in improved sleep patterns.
Future studies are required to determine whether similar sleep benefits apply to other jellyfish species or even mammals. The researchers also found comparable results with starlet sea anemones (Nematostella vectensis), marking a significant step in confirming sleep in these organisms, according to Appelbaum.
Far from the shore, in the immense stretches of the open ocean, resides an uncommon assembly of creatures known as “Neustons.”
This environment is a vast, two-dimensional layer of the ocean that bridges the atmosphere with the sea.
Among this group, one of the most fascinating beings is the blue dragon, a kind of sea slug, or naujibrance, more widely recognized as the blue dragon, the sea swallow, or Glaucus atlanticus.
Blue dragons float on the surface, buoyed by the air bubbles they have ingested. To evade predators, they employ a unique biological strategy called countershading.
The underside of their body, positioned upside down, exhibits a bright blue hue that camouflages it against the ocean below, concealing it from aerial hunters above.
Conversely, the side that hangs from the surface boasts silver stripes that mimic the shimmering ocean surface, aiding swimming predators in their upward gaze.
Overall, the blue dragon appears peculiar owing to its sea slug nature. The main body, measuring about 3cm (0.4 inches), seems somewhat sluggish, but it features elongated appendages resembling fingers of varying lengths.
These appendages are not used for waving or swimming; they are anatomical structures called ceratha, essentially serving as a secondary gill by extending the intestines and respiratory system to facilitate breathing.
Like many sea slug species, the Blue Dragon utilizes its ceratha as a weapon. They are notorious hunters, primarily targeting other blue-hued Neustons, including Portuguese man o’ war (Physalia physalis) and jellyfish-like creatures like blue buttons (Porpita porpita) and by-the-wind sailors (Velella velella).
Blue dragons can inject venom into these organisms without fear of being stung.
‘They are vicious hunters, and their main prey is the other members of Neuston’ – Photo credit: Matty Smith Photo
Remarkably, these sea slugs can recycle their prey’s toxins, maintaining them intact and incorporating them into their ceratha.
When threatened by predators, they can launch these toxins as a potent defense mechanism.
Modern challenges pose threats to Blue Dragons and their fellow Neuston inhabitants. A study conducted between Hawaii and California reveals that they inhabit the same remote regions of the infamous Pacific Ocean, including the Great Pacific Garbage Patch, where floating plastic debris accumulates due to swirling ocean currents.
One approach to combat this plastic pollution involves placing a net between two vessels to retrieve debris from the surface. However, this method could inadvertently capture a significant number of Neustons.
The complete ecological consequences of this method remain unclear, but it may have significant repercussions on the marine food web. These creatures serve as crucial food sources for a variety of marine species, such as sea turtles and seabirds.
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These stunning and eerie visuals showcase creatures born in Europe’s largest jellyfish breeding facility.
Photographer Heidi and Hans Jurgen Koch utilized a macro lens and studio lighting to create these images, though I was particularly intrigued by the jellyfish’s location, which cannot be photographed as it sinks to the bottom of a typical aquarium. The animals require “jellyfish” Kraisel or gyroscopes to generate necessary water movements; without them, swimming and feeding is impossible.
Moon jellyfish (Aurelia aurita)
Heidi and Hans Jurgen Koch
As jellyfish populations grow, they are increasingly seen as both an environmental challenge and a source of sustainable solutions, Koch asserts. With ocean temperatures rising, and issues like pollution and overfishing becoming more pressing, jellyfish numbers are surging, posing serious risks to ecosystems and economies.
Mangrove Jellyfish (Cassiopea xamachana)
Heidi and Hans Jurgen Koch
Nevertheless, jellyfish also offer significant potential, including uses as animal feed, fertilizers, and even superfoods for humans, thanks to their anti-inflammatory and immunologically beneficial compounds. Their mucus can also serve as biofilters to keep plastics out of the oceans.
Pacific Compass Jellyfish (Chrysaora fuscescens) is featured in the main image. These jellyfish will be sent to zoos, aquariums, and research facilities. Below, the gyroscope simulates ocean currents for the Moon Jellyfish (Aurelia aurita). The pipette in the photograph shows Mangrove Jellyfish (Cassiopea xamachana).
Heidi and Hans Jurgen Koch
As they mature, jellyfish reside on the seafloor, orienting their tentacles toward sunlight, where they have a symbiotic relationship with single-celled algae that assist with photosynthesis. The image above depicts jellyfish specimens being evaluated prior to shipment.
A shimmering sea creature known as a comb jelly exhibits incredible abilities. Despite being injured, two comb jellies can fuse into one body without experiencing tissue rejection, unlike other animals. Moreover, their nervous systems merge, and their digestive tracts combine to share food.
This discovery could assist researchers in understanding how the immune system evolved to differentiate an organism’s own tissues from those of another organism, as well as shed light on the evolution of the nervous system.
Although commonly referred to as comb jellies or ctenophores, they are distinct from jellyfish due to their unique body structures. These creatures are the most ancient beings to have branched off from the common ancestor of all animals, making them a captivating subject for scientists studying early animal evolution. Their nervous system, composed of interconnected neurons forming a continuous network, sets them apart from other animals.
While studying the vibrant combs of ctenophores, specifically Mnemiopsis leidii, at the University of Exeter in the UK, researcher Kei Shirokura noticed a unique specimen with two posterior ends and apical organs. This prompted further investigation.
Through experimentation involving cutting out pieces from unrelated individuals and pairing them together, Shirokura discovered that in most cases, the two bodies seamlessly merged into one within hours. The absence of tissue rejection suggested a lack of xenorecognition, indicating an inability to distinguish between self and non-self.
When prodded, the fused body responded collectively, demonstrating complete integration of the nervous systems. Additionally, the digestive tracts fused, allowing shared food consumption through a single entry point.
This groundbreaking discovery raises questions about when animals developed heterogeneous cognition and the mechanisms behind neural network formation and information processing. Similarly, ctenophores possess the ability to revert from adulthood to a larval-like stage under certain conditions, hinting at a common ancestral characteristic shared among animals.
The potential applications of ctenophores in understanding biological processes like tissue rejection, regeneration, and aging, which are relevant to human health, make them a valuable model for future research.
Astronomers ESO’s Very Low Tilt Survey Telescope The Chilean VST satellite has captured a stunning image of the distorted spiral galaxy NGC 3312.
This VST image shows the spiral galaxy NGC 3312. Image courtesy of ESO / INAF / M. Spavone / E. Iodice.
NGC 3312 It is located in the constellation Hydra and is more than 160 million light years away from Earth.
Also known as ESO 501-43, IC 629, IRAS 10346-2718, LEDA 31513, Found It was discovered on March 26, 1835 by British astronomer John Herschel.
NGC 3312 is Hydra I Cluster (Abell 1060) is a galaxy cluster containing over 150 luminous galaxies.
As galaxies move through the hotter gas in the cluster, they lose cooler gas.
It is likely distorted by the cluster’s main elliptical galaxies, NGC 3309 and NGC 3311.
“The spiral galaxy in the centre of this VST image appears fuzzy across the entire screen, seemingly leaking its contents into the surrounding space,” ESO astronomers said in a statement.
“This is NGC 3312, the victim of an astrophysical robbery: ram-pressure stripping.”
“This occurs when galaxies move through a dense fluid, such as the hot gas suspended between galaxies in a cluster,” the researchers explained.
“This hot gas is pulled by the cooler gas in the outer shell of the galaxy, causing it to be pulled out of the galaxy and leak out into space.”
“This cold gas is the raw material for star formation, which means that galaxies that are losing gas in this way are at risk of losing a decrease in their stellar population.”
“Affected galaxies, typically those that fall into the center of a cluster, tend to eventually form long trailing tendrils of gas behind them, which is where their nickname ‘jellyfish galaxies’ comes from.”
“This is just one of the many astronomical processes that make our cosmic pictures so diverse and fascinating.”
A jellyfish-shaped robot made from magnetic fluid can be controlled with light through an underwater obstacle course, and swarms of these soft robots could be useful for delivering chemicals throughout liquid mixtures or moving fluids through a lab-on-a-chip.
Ferrofluid droplets are made of magnetic nanoparticles suspended in oil, and can move across a flat surface and change shape when guided in different directions by a magnet. When these droplets are immersed in water and exposed to light, Sun Meng Meng, a researcher from the Max Planck Institute for Intelligent Systems in Germany, and his colleagues have succeeded in creating an object that defies gravity.
When ferrofluid absorbs light (and it’s particularly good at that, because it’s black), it heats up, causing tiny bubbles inside it to expand. This makes the droplets below the surface lighter and more buoyant, allowing them to float upwards, Sun says.
He and his colleagues built a soft robot with droplets of magnetic fluid encased in a jellyfish-shaped hydrogel shell, and then tested it. The researchers devised an obstacle course at the bottom of a tank of water that included a variety of platforms of different heights. They guided the robot through the course and had it navigate over the platforms.
In one experiment, they lined up three robotic jellyfish on the bottom of a tank and heated them with a laser, causing them to move upward one after the other. Sunlight focused by a magnifying glass had a similar effect, causing the jellyfish to float vertically.
Hamid Marvi, the Arizona State University researcher, says controlling an entire swarm of droplets simultaneously could one day be useful for delivering medicines or performing other functions in the human body. By encasing them in hydrogel, he says, light could be used to guide the ferrofluid droplets and move the hydrogel itself, enabling complex movements.
But Mulvey says many details need to be worked out before the ferrofluid can be used for medical purposes, such as whether it’s safe to ingest it. Sun and his colleagues hope to answer some of those open questions. For example, they hope to find a way to use optical fibers that can be inserted into the body to guide the robot, rather than lasers or sunlight.
New research reveals how cladoceran jellyfish can regenerate tentacles in just a few days, highlighting the role of unique stem-like proliferating cells in this rapid regeneration process. This breakthrough provides insight into similar regeneration processes in other species. Credit: SciTechDaily.com
Japanese scientists have discovered that the cladoceran jellyfish uses stem-like proliferating cells to regenerate its tentacles, providing new insights into the process of blastogenesis and its evolutionary similarities in other organisms. . seed Like a salamander.
A type of jellyfish about the size of a little fingernail cladonema Amputated tentacles can regrow in a few days, but how do they regrow? Functional tissue regeneration across species such as salamanders and insects repairs damage and grows into missing appendages It relies on its ability to form blastocytes, which are masses of undifferentiated cells. Jellyfish, like other cnidarians such as corals and sea anemones, exhibit high regenerative abilities, but how their vital blastema cells are formed has remained a mystery until now.
Japanese research team reveals that stem-like proliferating cells (actively growing and dividing but not yet differentiated into specific cell types) appear at injury sites and help form blastomas. I made it.
The results of this study were published in the journal Science on December 21st. PLOS Biology.
The jellyfish Cladonema pacificum exhibits branched tentacles that can strongly regenerate after amputation.Credit: Sou Fujita, University of Tokyo
“Importantly, these stem-like proliferating cells in the blastema are different from the resident stem cells localized in the tentacles,” said corresponding author Yuichiro Nakajima, a lecturer at the University of Tokyo’s Graduate School of Pharmaceutical Sciences. “Repair-specific proliferating cells primarily contribute to the newly formed tentacle epithelium (thin outer layer).”
According to Nakajima, the resident stem cells present in and near the tentacles are responsible for generating all cell lineages during homeostasis and regeneration, and maintain all the cells needed throughout the jellyfish’s life. means to repair. Repair-specific proliferating cells appear only upon injury.
“The combination of resident stem cells and repair-specific proliferating cells enables the rapid regeneration of functional tentacles within a few days,” Professor Nakajima said, adding that jellyfish use their tentacles to hunt and feed. he pointed out.
Resident stem cells (green) and repair-specific proliferating cells (red) contribute to the regeneration of Cladonema tentacles.Credit: Sou Fujita, University of Tokyo
According to lead author Sosuke Fujita, a postdoctoral researcher in the same laboratory as Nakajima at the Graduate School of Pharmaceutical Sciences, the discovery will help researchers understand how blastoma formation differs between different animal groups. It shows that you understand.
“In this study, our aim was to use the tentacles of the cnidarian jellyfish to address the mechanisms of blastogenesis. cladonema “As a regeneration model for non-bilateral animals, or animals that do not form bilaterally symmetrically during embryonic development,” Professor Fujita said, explaining that this study could provide insights from an evolutionary perspective.
For example, salamanders are bilaterally symmetrical animals that can regenerate limbs. Their limbs contain stem cells that are restricted to the needs of specific cell types, and this process is thought to function similarly to the repair-specific proliferating cells observed in jellyfish.
“Given that repair-specific proliferating cells are similar to restricted stem cells in the limbs of bilateral salamanders, the formation of blastema by repair-specific proliferating cells has been linked to complex organs and appendages during animal evolution. We can infer that this is a common feature that was acquired independently for organ regeneration,” said Fujita. Said.
After 72 hours of amputation, Cladonema’s regenerating tentacles are fully functional.Credit: Sou Fujita, University of Tokyo
However, the cellular origin of the repair-specific proliferating cells observed in blastema cells remains unclear, and researchers believe that the tools currently available to investigate their origin are too limited. They say they are unable to elucidate or identify other distinct stem-like cells. cell.
“It is essential to introduce genetic tools that allow tracing and intracellular manipulation of specific cell lineages. cladonema‘ said Nakajima. “Ultimately, understanding the mechanisms of blastoma formation in regenerating animals, including jellyfish, may help us identify cellular and molecular components that improve our own regenerative abilities.”
Reference: “Distinct stem-like cell populations promote functional regeneration of Cladonema medusa tentacles” by Sosuke Fujita, Mako Takahashi, Manabu Kumano, Erina Kuranaga, Masayuki Miura, and Yuichiro Nakajima, December 21, 2023. PLOS Biology. DOI: 10.1371/journal.pbio.3002435
This research was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science, the Japan Science and Technology Agency, the Japan Agency for Medical Research and Development, and a grant from the National Institute for Basic Biology Joint Research Project.
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