Do all animals sleep? Sleep has been observed in many vertebrates, and there is a growing body of evidence for sleep-like states in arthropods and nematodes 1–5. Here we show that sleep is also ...present in Cnidaria 6–8, an earlier-branching metazoan lineage. Cnidaria and Ctenophora are the first metazoan phyla to evolve tissue-level organization and differentiated cell types, such as neurons and muscle 9–15. In Cnidaria, neurons are organized into a non-centralized radially symmetric nerve net 11, 13, 15–17 that nevertheless shares fundamental properties with the vertebrate nervous system: action potentials, synaptic transmission, neuropeptides, and neurotransmitters 15–20. It was reported that cnidarian soft corals 21 and box jellyfish 22, 23 exhibit periods of quiescence, a pre-requisite for sleep-like states, prompting us to ask whether sleep is present in Cnidaria. Within Cnidaria, the upside-down jellyfish Cassiopea spp. displays a quantifiable pulsing behavior, allowing us to perform long-term behavioral tracking. Monitoring of Cassiopea pulsing activity for consecutive days and nights revealed behavioral quiescence at night that is rapidly reversible, as well as a delayed response to stimulation in the quiescent state. When deprived of nighttime quiescence, Cassiopea exhibited decreased activity and reduced responsiveness to a sensory stimulus during the subsequent day, consistent with homeostatic regulation of the quiescent state. Together, these results indicate that Cassiopea has a sleep-like state, supporting the hypothesis that sleep arose early in the metazoan lineage, prior to the emergence of a centralized nervous system.
•Cassiopea jellyfish exhibit reversible behavioral quiescence during the night•Cassiopea show reduced responsiveness to stimuli during their quiescent state•The nighttime quiescence is regulated by both homeostatic and circadian systems•Pharmacological studies show evidence of molecular conservation of sleep regulation
Understanding the phylogenetic roots of behaviors sheds light on the evolutionary forces that shape them. Sleep has been observed in worms, flies, zebrafish, and mice. Nath et al. discover that jellyfish have a sleep-like state. This shifts the known root of sleep in the phylogenetic tree prior to the emergence of a centralized nervous system.
Due to their high-water content and low nutritional value, jellyfish have long been considered ‘dead ends’ in marine food webs. However, it was revealed that silver pomfret (Pampus argenteus) ...preferentially hunts jellyfish, and consuming jellyfish alters intestine histology. To better understand the physiological responses of midgut tissues after consuming jellyfish, we compared the transcriptomes and proteomes of jellyfish-fed and jellyfish-unfed groups, and identified 1167 differentially expressed genes (DEGs) and 471 differentially expressed proteins (DEPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that unsaturated fatty acid metabolism pathways, especially cholesterol metabolism, were the most enriched biological pathways. Apolipoprotein E was downregulated at both transcriptome and proteome levels, and it was found to negatively regulate jellyfish consumption. These results provide deep insight into the molecular mechanisms regulating jellyfish consumption in Pampus argenteus.
•Eating jellyfish has a dramatic impact on the gut histology of silver pomfret.•Only 29 DEGs and DEPs overlapped.•Cholesterol metabolism plays a central role after consuming jellyfish.•ApoE negatively regulates jellyfish consumption.
Western Baltic spring spawning herring (Clupea harengus, L.) is a commercially important fish stock currently suffering a strong decline. Larval survival is essential for stock recruitment and can be ...substantially decreased by predation. The comb jelly Mnemiopsis leidyi A. Agassiz, 1865, is a lobate ctenophore which is invasive to the Baltic Sea and a known ichthyoplankton predator. However, predation on herring larvae in the Baltic Sea by M. leidyi has not been studied since its initial establishment in 2006. To address this knowledge gap, we conducted feeding experiments to investigate (1) the predation capability of M. leidyi on herring yolk-sac larvae, and (2) the influence of larval age, (3) predator size and (4) the presence of alternative prey on the clearance rate of M. leidyi on herring yolk-sac larvae. Our results showed that M. leidyi exhibited the ability to capture and digest herring larvae. The clearance rates of M. leidyi on herring larvae decreased with larval age and increased with predator size, while the presence of alternative prey had no effect on clearance rates. This finding suggests that M. leidyi can efficiently consume herring yolk-sac larvae under laboratory conditions. However, further investigations using mesocosm or field studies are necessary to evaluate the potential impact of M. leidyi on the mortality and recruitment of herring yolk-sac larvae under Baltic Sea field conditions.
•Mnemiopsis leidyi is capable of catching and digesting herring yolk-sac larvae.•Predation on herring larvae is decreasing with prey age and increasing with predator size.•Predation of M. leidyi on herring larvae is not affected by the presence of alternative natural prey represented by the copepod Acartia tonsa.•Substantial predation of M. leidyi on yolk-sac herring larvae may occur in the field, when both overlap spatially and temporarily.
Exploring the world beneath the ocean has been a difficult task, especially in depths that are unsafe for humans. Studying underwater creatures can be very sensitive due to disturbances resulting ...from typical remotely operated vehicles (ROVs) currently used. Soft robots consist of elastomeric materials, compliant actuators, sensors and other supporting structures, which enable them to be used for numerous applications due to their flexibility, light weight, low noise, and many degrees of freedom. Mechanical actuators, such as pneumatic actuators and servomotors, introduce design constraints related to their size, weight, and cost. Moreover, vibration and noise are undesired attributes that preclude the use of robots developed with such technologies and might disturb the test environment. This paper presents a robust design of a jellyfish-like robot with eight bell segments, named KryptoJelly. The presented robot can perform multidirectional swimming by NiTi shape memory alloys (SMA) actuators confined in a conduit and activated by electrical current stimulation. KryptoJelly is constructed from a 3D printed rigid structure and a soft silicone bell that closely mimics the biological locomotion and appearance of a jellyfish found in nature; the Chrysaora colorata species. Four 127 μm diameter SMA wires (of mass 14 mg each) were used per channel to deform the silicone bell margin. The robot can operate up to 1608 cycles continuously for 1.5 h underwater at high power input (3 times higher than the standard) and sustain its own total body mass of 650 g (∼6000 times the weight of the actuators used). KryptoJelly is able to maneuver in both vertical and horizontal directions during bell contraction-expansion cycles. A study on the effect of multistage-power-time input sequence of NiTi SMA actuators and bell design, which results in swimming, is presented. This work has shown the great potential of employing smart materials in biomimetic soft robots, that can be deployed for eco-friendly underwater exploration or other applications.
Soft actuators that exhibit large deformation and can move at a fast speed in response to external stimuli have been in high demand for biomimetic applications. In this paper, we propose a convenient ...approach to fabricate a reversible and thermal-responsive composite hydrogel. Under the irradiation of visible light, the striped hydrogel can bend at a speed of up to 65.72°/s with carbon nanotubes loaded at a concentration of 3 mg/mL. A jellyfish-like miniature soft robot is made using this hydrogel. When driven by visible light, the robot can move at a maximum speed of 3.37 mm/s. Besides swimming, other motion modes, including walking and jumping, are also achieved by the robot. In addition, the robot can perform directional transportation of tiny objects. As a new actuation approach for the research of jellyfish-like miniature soft robots, this work is of great significance to the development of flexible bionic robots. Moreover, this work also offers some important insights into the research of biomimetic robots driven by visible light.
•A homogenous polysaccharide (JSP-11) was isolated from jellyfish.•The structural features of JSP-11 were characterized.•The activation of macrophages by JSP-11 and the related mechanism were ...studied.
A new polysaccharide (JSP-11) with a molecular weight of 1.25×106Da was extracted and purified from jellyfish. Monosaccharide analysis showed that JSP-11 was composed of mannose, galactose and glucuronic acid with a molar ratio of 2.18:1.00:1.94. According to the analysis of fourier transform-infrared spectroscopy, methylation analysis, and NMR spectroscopy, JSP-11 was determined to contain a linear backbone which consisted of (1→3,6)-linked β-d-Manp and (1→6)-linked β-d-Galp. The branch of (1→)-linked α-d-GlcpA was attached to the C-3 position of (1→3,6)-linked β-d-Manp in the backbone. The immunomodulatory assay exhibited that JSP-11 could significantly enhance the viability of RAW 264.7 macrophage cells, and promote the release of NO, TNF-α, and IL-1β via activating NF-κB, MAPKs and PI3K/Akt signal pathways.
Radiation (e.g., nuclear leakage) is a common harmful factor in the ocean that potentially affects the microbial community in nearby benthic hosts such as jellyfish polyps, which is essential for the ...maintenance of jellyfish populations and high-quality medusae. After comparison with the microbial community of medusae, the effect of 60Co-γ on the microbial community in Aurelia coerulea polyps was dynamically tested using 16S rRNA gene sequencing. Our results suggested that Proteobacteria (76.19 ± 3.24%), Tenericutes (12.93 ± 3.20%) and Firmicutes (8.33 ± 1.06%) are most abundant in medusae, while Proteobacteria (29.49 ± 2.29%), Firmicutes (46.25 ± 5.59%), and Bacteroidetes (20.16 ± 2.65%) are the top three phyla in polyps. After 60Co-γ radiation, the proportion of Proteobacteria increased from 29.49 ± 2.29% to 59.40 ± 3.09% over 5 days, while that of Firmicutes decreased from 46.25 ± 5.59% to 13.58 ± 3.74%. At the class level, Gammaproteobacteria continually increased during the 5 days after radiation exposure, whereas Bacilli declined, followed by partial recovery, and Alphaproteobacteria and Flavobacteriia remained almost unchanged. Intriguingly, Staphylococcus from Firmicutes and three other genera, Rhodobacter, Vibrio, and Methylophaga, from Proteobacteria greatly overlapped according to their KEGG functions. It is concluded that the microbial community in A. coerulea polyps is distinct from that in the medusae and is greatly affected by 60Co-γ exposure, with a growth (0–3 d) period and a redistribution (3–5 d) period. The dynamic change in the microbial community is probably an important self-defense process in response to external interference that is regulated by the host's physiological characteristics and the intense interspecific competition among symbiotic microbes with similar functions and functional redundancies.
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•The microbial community in Aurelia coerulea polyps is distinct from that in medusae.•The impacts of radiation on the bacterial community of Aurelia coerulea polyps were clarified.•There was a significant negative correlation between Bacilli and Gammaproteobacteria after radiation.•The self-defense of hosts to external interference may drive the dynamic change of the microbial community after radiation.
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•Bioinspired jellyfish-like carbon/manganese nanomotor is developed.•Near-infrared light and H2O2 dual-propulsion is achieved.•Cooperation of dual-propulsion and •OH catalytic ...activity actively enhances tumor chemodynamic therapy.
Chemodynamic therapy (CDT), which catalyzes the production of highly toxic reactive oxygen species (ROS), has been widely used in tumor therapy in the past five years. However, most of the current nanomaterials for CDT are difficult to penetrate into the tumor effectively due to the lack of motility, resulting in an unsatisfactory CDT effect. Herein, bioinspired jellyfish-like carbon/manganese nanomotors (JCMNs) are designed to achieve hydrogen peroxide (H2O2) and NIR light dual-propulsion for the enhanced CDT therapy. Based on the jellyfish-like asymmetric structure, the manganese component can catalyze H2O2 to generate chemical concentration gradient, propelling JCMNs to dynamically generate ROS in cells by self-diffusiophoresis. In addition, the carbon component of JCMNs can absorb near-infrared (NIR) light to produce a temperature gradient, driving JCMNs to enhance tumor penetration by self-thermophoresis. The combination of chemical and NIR light propulsions significantly improves the efficiency of tumor CDT, revealing that it should be a reasonable strategy to promote the development of nanobiomedicine by endowing nanosystems with propulsion capacity.
Jellyfish, with their tetraradial symmetry, offer a novel paradigm for addressing patterning mechanisms during regeneration. Here we show that an interplay between mechanical forces, cell migration ...and proliferation allows jellyfish fragments to regain shape and functionality rapidly, notably by efficient restoration of the central feeding organ (manubrium). Fragmentation first triggers actomyosin-powered remodeling that restores body umbrella shape, causing radial smooth muscle fibers to converge around 'hubs' which serve as positional landmarks. Stabilization of these hubs, and associated expression of
, depends on the configuration of the adjoining muscle fiber 'spokes'. Stabilized hubs presage the site of the manubrium blastema, whose growth is Wnt/β-catenin dependent and fueled by both cell proliferation and long-range cell recruitment. Manubrium morphogenesis is modulated by its connections with the gastrovascular canal system. We conclude that body patterning in regenerating jellyfish emerges mainly from local interactions, triggered and directed by the remodeling process.
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