Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S. malayensis at three different temperatures: 10, 15 and 20 °C. Results showed significant increases of polyps at 15 and 20 °C, and a minimum at 10 °C, corresponding with daily budding rates of 6.61% ± 0.92%, 5.85% ± 2.36% and 0.66% ± 0.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at the ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea.

Current climate changes cause increasing stress to corals, which can disrupt host-symbiont relationships, leading to bleaching and mortality. While stress responses are well-documented at the coral colony and reef scales, less is known about how stress responses affect different compartments within the coral holobiont. Here, we investigated the impact of thermal stress on macro– and microscale compartments, including the endoderm-lined gastrovascular cavity (GVC) and the ectoderm-lined external tissue surface, in two tropical corals, Caulastrea curvata and Galaxea fascicularis . We assessed the coral physiological status via respirometry, variable chlorophyll fluorometry, O ₂ and H ₂ O ₂ microsensor analyses, chlorophyll measurements, and oxidative stress biomarkers during a 14-day thermal stress exposure. Under heat stress, both species showed a reduced O ₂ concentration in the GVC by up to 90% in the light, reaching hypoxic (< 50 µmol O ₂ L ⁻¹ ) to anoxic levels, while the O ₂ concentration in the external surface tissue of C. curvata decreased by 20%. Moreover, no changes in the H ₂ O ₂ dynamics of the coral’s external tissue surface were detected. Lipid peroxidation in the gastrodermis of both species increased significantly by 90–198% indicating oxidative damage, although antioxidant enzyme activity (SOD and CAT), chlorophyll content, and bulk metabolic rates (respiration and photosynthesis) remained stable. Our findings indicated that thermal stress could affect the microenvironment of corals, particularly in the GVC, without visible bleaching or major disruptions in bulk physiology. This suggested the importance of microenvironmental metrics for the early detection of coral physiological stress.

Assuming that cognitive complexity follows a single, centralized trajectory overlooks key gaps: (1) the scarcity of cognitive studies on non-centralized species; (2) the potential of alternative neural architectures to support complex behavior; and (3) the influence of ecological niche pressures. Here we present evidence of curiosity-like behavior in a jellyfish, challenging the assumed link between centralized brains and complex cognition.

Sponges are now requested for their commercial, industrial and pharmaceutical importance. This led to an increase in demand in the global markets with uncontrolled and excessive harvesting pressure that, together with diseases outbreaks, put wild populations at risk, with several habitats completely looted. Aquaculture of sponge fragments poses an alternative to wild collection since fragment regeneration is easy, cheap and efficient. We chose as subject of our study Spongia anclotea, common to the tropical Western Atlantic, due to its high request on the market for cosmetics, body care and pharmaceutical applications. We set a low-cost sponge farm made of cheap materials, thus affordable for local communities, which did not require significant maintenance. The growth and survival rate of 384 out of 2304 randomly chosen sponges have been investigated over a 4-year period. At the end of the study, sponges increased by an average rate of 380% ± 275% of their initial volume (with a maximum of 1480%) and 87.5% of sponges survived (death and detach during the whole period were considered as mortality). Farmed sponges from our structure resulted characterized by superior quality and shape compared to collected wild individuals from the area and, after six years of cultivation (4 years of the present study + 2 years of forecasted growth based on our findings), this improved quality could yield higher profits (618 USD vs. 547 USD, respectively, for a standard stock size). This experimental setup can be considered a good alternative to sponge harvesting and a good economic opportunity for developing countries.

Historically, research on jellyfish anatomy has been viewed as secondary in importance and has not benefited from technical advances that could improve the quality of the results when compared to other disciplines. The most notable example is the anatomical research on jellyfish, which has been done using conventional methods for many years. Thus far, recent studies have shown that X-ray microtomography (µCT) and resin endocasts can yield outputs with remarkably high detail quality. The application of a similar protocol to Cotylorhiza tuberculata has allowed us to redescribe the anatomy of this species’ gastrovascular system, providing numerous additional details, among them the double constricted canal structure present in the oral arms, which was absent in previous descriptions. Additionally, functional anatomy experiments have revealed a double circulation system within these canals, featuring specialized oral arms’ openings for intake and outflow, as previously observed in Rhizostoma pulmo . These findings challenge the theory of a simple digestive system in scyphozoans featuring openings that acts both as mouths and anuses. Given the genetic distance between Cotylorhiza tuberculata and Rhizostoma pulmo , which belong to different suborders (Kolpophorae and Dactyliophorae, respectively), we propose that this complex gastrovascular circulation pattern may be more widespread among the Rhizostomeae.

Conservation management, aimed at mitigating the ongoing biodiversity loss, critically relies on ecosystem monitoring to enable accurate estimates of species distributions and population sizes. Environmental DNA (eDNA) analysis has become increasingly popular for non-invasive and high-throughput species assessment, including fish species diversity. Beyond the established sample collection protocols, natural samplers of eDNA (nsDNA) – organisms that trap environmental genetic material in their tissues – show considerable promise, with recent work especially demonstrating the remarkable effectiveness of sea sponges. Here, the potential of jellyfish (phylum Cnidaria) to serve as motile, marine, pelagic natural samplers of eDNA was investigated through DNA metabarcoding using fish specific primers. Jellyfish are opportunistic marine predators known to consume fish eggs and larvae and their presence has been associated with certain fish species, making them potentially useful for open water fish assessment. Four species, the many-ribbed jellyfish ( Aequorea forskalea , Class Hydrozoa), the moon jelly ( Aurelia solida , Class Scyphozoa, Order Semaeostomeae), the barrel jellyfish ( Rhizostoma pulmo Class Scyphozoa, Order Rhizostomeae) and the fried-egg jellyfish Cotylorhiza tuberculata (Class Scyphozoa, Order Rhizostomeae) were collected from the Italian waters of the Gulf of Trieste (northern Adriatic Sea) and nsDNA isolated, sequenced and analysed. Across all species, 28 fish Molecular Operational Taxonomic Units (MOTUs) were detected including pelagic species, benthic species likely spawning at the time of sampling, and species known to associate with the presence of jellyfish. We highlight the potential of jellyfish as tools for enhancing biodiversity monitoring, particularly in remote and inaccessible areas where conventional surveys may be difficult to employ.