Sea urchins are renowned for their capacity to shape shallow reef community structure and function, especially when at high densities. However, most quantitative assessments of urchin densities are based on diurnal surveys, despite the nocturnal emergence of urchins being a well-recognised phenomenon. The value of such diurnal density estimates is, therefore, inherently dependent on the extent of nocturnal urchin emergence and the consistency of this diel behaviour under different contexts. Yet, our understanding of nocturnal urchin emergence under different local conditions at broad scales including between tropical and temperate reefs, remains largely unresolved. Here, we evaluate the extent of nocturnal urchin emergence, and assess how this varied with potential predictors, using paired day and night surveys across a total of 42 reef sites spanning tropical (n=23) and temperate (n=19) Australia. Among kelp-dominated temperate rocky reefs, urchin densities and biomass were ∼7-8-fold greater than observed on tropical coral reefs. Regardless of realm, urchin densities and biomass were consistently higher at night, with tropical reefs showing the greatest diel differences (3.5-fold higher density and 3.0-fold higher biomass) compared to temperate reefs (1.4-fold and 1.7-fold, respectively). Gradient Boosted Regression Trees revealed that mean sea surface temperature (SST) was the strongest predictor of the relative extent of nocturnal urchin emergence, with higher relative emergence on reefs with warmer SST, corresponding with strong patterns in nocturnal emergence peaking toward equatorial latitudes. Our findings show that daytime surveys likely greatly underestimate urchin activity, population size, and ecological impacts, particularly on tropical reefs, with important consequences for reef monitoring and management.

Stocking density affects survival and gonad indices of sea urchins during commercial scale roe-enhancement

Ecotoxicological effects of cadmium on Echinometra mathaei: Oxidative stress, genotoxicity, and biochemical responses.

Schools against plastics: Schooling environmentally conscious students and supporting research on marine litter and microplastics.

The eukaryotic cell cycle is one of the most fundamental biological processes, ensuring the accurate duplication and segregation of the genome during mitosis. Decades of research across model systems have shown that this process is orchestrated by a family of protein kinases known as cyclin-dependent kinases (Cdks). Together with their cyclin partners, Cdks act as master regulators of cell division, coordinating DNA replication, chromosome segregation, and cytokinesis with remarkable precision. The discovery of Cdks and cyclins in yeast and sea urchins, celebrated with the Nobel Prize of Hartwell, Hunt, and Nurse (awarded in 2001), established the conceptual framework for understanding how oscillations in kinase activities drive cell cycle progression in a unidirectional and irreversible manner. Over the past thirty years, a central question has been whether cell cycle control relies primarily on the quantitative level of Cdk1 activity or whether distinct qualitative functions of cyclin-Cdk1 complexes ensure the correct ordering of events. Addressing this question required new genetic and biochemical tools capable of controlling Cdk1 activity with high temporal resolution and specificity. A turning point came in 2000 with the development of the analogue-sensitive Cdk1 allele by the Shokat laboratory. This approach replaced classical temperature-sensitive alleles with a version of Cdk1 that can be selectively inhibited by bulky ATP analogues. Beyond specific inhibition, the system was soon adapted to directly label and identify Cdk1 substrates, coupling chemical genetics with the emerging power of mass spectrometry. This review outlines the conceptual frameworks of quantitative and qualitative models of Cdk1 control. It also highlights how these ideas have been experimentally dissected, tracing the development of the Cdk1 Shokat system and advances from synthetic biology and phosphoproteomics in decoding phosphorylation logic, and how these concepts apply to meiosis. These studies draw primarily on budding yeast and fission yeast which have a single Cdk, making them convenient models for studying core principles of cell cycle regulation. Key insights from vertebrates are also integrated to illustrate principles that extend to other eukaryotes.

Sea urchins are interesting creatures that play important ecological roles in the sea and are popular for their culinary and medicinal uses, which belong to phylum of Echinodermata. However, rapid environmental changes create a significant impact on marine species, including sea urchins, causing them severe stress. To address this issue, scientists are attempting to cultivate sea urchins in aquaculture to aid both conservation and commercial efforts. In this study, we aimed to investigate the physiological effects of stressors on sea urchin Arbacia punctulata, using three different stress conditions: increased temperature as a physical stressor, inoculation of lipopolysaccharides (LPS) as a chemical stressor, and a combination of both (increased temperature and LPS). We collected coelomic fluid (CF) from all the experimental groups at day 1, day 3, day 7, and day 10 and observed significant variations in the numbers of total and differential coelomocytes, namely, phagocytic cells, vibratile cells, red spherule cells, and colorless spherule cells in different stress conditions compared to controlled conditions (p < 0.05). The immune cells of sea urchins, especially phagocytic cells and red spherule cells, actively responded with LPS (4 µg/ml of CF/day). Our study also found a significant amount of protein in sea urchin’s cell free coelomic fluid exposed to increased temperature stress (p < 0.05) compared to that of control group. Both physical and chemical stressors impacted the growth and reproduction of sea urchins for long time exposure to stressors. We also observed lower gonadosomatic index (GSI) in the group exposed combined stressors: LPS inoculation (4 µg/ml of CF/day) and increased temperature (1˚C/day) in comparison with the control group (p < 0.05) at day 10.

ABSTRACT A facile green synthesis route using Ocimum sanctum (Tulsi) leaf extract was used to synthesise BaO nanoparticles. The prepared BaO exhibited a hierarchical sea urchin-like nanostructure (NS) and was characterised using various analytical and spectroscopic techniques. XRD data indicated that the nanostructure exhibits a tetragonal phase with an assessed average crystallite size of 107 nm. SEM study unveils needle-like cluster morphology, indicating highly crystalline growth of the nanomaterials. TEM analysis further confirmed the 3D hierarchical sea urchin-like architecture, consisting of a central core from which sharp one-dimensional (1D) nanoneedles radiate outward. UV – Vis spectroscopy showed that the bandgap energy of the nanophase BaO was 3.97 eV, lower than that of bulk BaO (4.4 eV). The synthesised BaO NS were evaluated for the photocatalytic degradation of Fast Blue (FB) and Fast Orange (FO) dyes under UV irradiation. The degradation process was monitored at the characteristic absorption maxima of 617 nm (FB) and 496 nm (FO), achieving maximum degradation efficiencies of 77.52% and 73.75%, respectively, which demonstrates enhanced photocatalytic activity. Furthermore, the BaO NS were investigated for electrochemical sensing of lead and lithium ions, exhibiting a positive shift in peak potential with increasing analyte concentration. Electrochemical impedance spectroscopy analysis using Nyquist plots established a charge transfer resistance (Rct) of precisely 3 Ω.

Experiments using Raman microspectroscopy and polarized light microscopy have provided evidence that cellophane undergoes biodegradation or chemical changes not only in the digestive tracts of sea urchins and periwinkles but also when exposed to the homogenized digestive organs of sea stars and sea urchins. Sea urchins (such as Strongylocentrotus intermedius) and periwinkles (Littorina brevicula) can ingest cellophane films, which are then shredded and modified in their digestive tracts, thereby increasing the content of microplastic particles in the surrounding environment. Raman microspectroscopy has shown the changes that occur in crystallinity and the thinning of plastic as it passes down the echinoderm digestive tract. This process makes the plastic more susceptible to further degradation in the marine environment.

The identification of SiMyD88 confirms the presence of a functional TLR-MyD88-IRAK signaling axis in the sea urchin Strongylocentrotus intermedius.

LC-MS-based non-targeted metabolomics analysis of sea urchin during frozen storage under different packaging methods.

Integrated Multi-Trophic Aquaculture (IMTA) is a sustainable aquaculture approach that recycles nutrients by co-culturing species from different trophic levels. This study assessed the biological feasibility of co -culturing the sea urchin Paracentrotus lividus with the polychaete Hediste diversicolor in a novel low-trophic IMTA configuration, using sea urchin faecal waste as a food source. Three experimental sea urchin diets (D1, D2, D3), varying in marine and plant-based ingredients, were tested over 40 days, including a novel fishmeal- and fish-oil-free diet (D1). Sea urchins showed no significant differences in somatic or gonadal growth between diets. In contrast, polychaetes exhibited substantial growth across all treatments, with the highest performance observed in those fed waste from the energy-rich, animal-based diet (D3). No significant dietary effects were detected on polychaete gametogenesis, although a maturation trend aligned with energy availability. Notably, polychaetes consuming waste from the diet free of fishmeal and fish oil (D1) displayed a significantly improved fatty acid profile, particularly in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. These results highlight both the influence of feed composition and the capacity of H. diversicolor to enhance the nutritional value of waste through differential assimilation and biosynthesis. By converting waste into high-value biomass, this co-culture model improves sustainability, contributes to reducing reliance on fish-oil inputs, and adds economic value to sea urchin aquaculture. • Sea urchins and polychaetes co-cultured in a novel low-trophic aquaculture design. • Polychaetes grew fastest on waste from the energy-rich, animal-based sea urchin diet. • Polychaete EPA and DHA levels differed among experimental diets. • Sea urchin waste ensured survival, nutrient recycling and fatty acid assimilation. • IMTA model supports sustainable, circular and high-value echinoderm aquaculture.

Multi-omics insights into the adaptation of sea urchins (Strongylocentrotus intermedius) to ocean oxygen fluctuations

Comprehensive analysis of metabolomic and transcriptomic provides insights on the phospholipid regulating LC-PUFAs accumulation in the gonads of sea urchin Strongylocentrotus intermedius.

Single-cell transcriptome reveals the regulatory effect of carboxypeptidase in metamorphosis of purple sea urchin Heliocidaris crassispina

Although the use of ultraviolet (UV) filters in personal care products is steadily increasing, their ecological consequences remain poorly characterized despite evidence of persistence and bioaccumulation in marine systems. In parallel, climate change stressors such as rising temperatures and fluctuations in salinity are known to modulate the toxicity of contaminants and the physiological tolerance of marine organisms. The combined action of these factors can intensify biological stress, highlighting the need for studies that evaluate pollutant effects under realistic multi-stressor scenarios. This study investigated the biochemical effects of octinoxate (also known as ethylhexyl methoxycinnamate, EHMC), a widely used organic UV filter, on the sea urchin Paracentrotus lividus under environmentally relevant conditions. A 28-day laboratory exposure was conducted using three EHMC concentrations (50, 500, and 5000ng/L) under control conditions (17°C, salinity 35) and climate change scenarios (21°C, salinity 40). Multiple biomarkers were analysed, including metabolic activity, antioxidant and biotransformation responses, redox balance, cellular damage, and neurotoxicity. Results showed that the biochemical responses of P. lividus were significantly influenced by environmental conditions. Combined exposure to EHMC and elevated temperature (21°C) induced marked oxidative stress, metabolic alterations, and shifts in detoxification responses. These effects were less pronounced under increased salinity, though still detectable. The present findings emphasize the heightened vulnerability of marine invertebrates to chemical pollutants under climate stress. Furthermore, the present study highlights the importance of integrating multiple stressors into ecotoxicological assessments and supports the use of bioindicator species, such as P. lividus, for more realistic environmental risk evaluations. Given that UV filters remain understudied contaminants and that data on their effects in echinoderms are still almost nonexistent, this work provides a timely contribution and highlights a critical knowledge gap that warrants urgent scientific attention.

Cellular solids ubiquitously exist in natural systems and are crucial for living organisms1,2. Their unique smooth branch and node morphologies are often seen as adaptations for enhanced mechanical performance3,4. Exploring alternative evolutionary functions can enrich the understanding of cellular solids, but it is frequently neglected. Here we show that the biomineralized cellular solids in echinoderm stereom (for example, sea urchin spine) have unexpected mechanoelectrical perception with response potential and response time, both of which are one to three orders of magnitude greater than those of echinoderm vision5. This exceptional perception originates from the gradient cellular solids (with varying void- or solid-phase diameters) along the [001] spine axis, generating a differential charge density across the stereom surface during liquid flow. Inspired by this natural wisdom, we create artificial spine-like structures using three-dimensional printing technology that exhibit three-fold higher voltage output and eight-fold greater amplitude differential than gradient-free samples, as well as a nature-inspired metamaterial mechanoreceptor capable of time-resolved self-monitoring information underwater. Our findings advance the understanding of load-sensitive biomimetic cellular solids (such as wood, sponge and trabecular bone), with the potential to develop functional gradient cellular materials towards underwater spatiotemporal sensing and water resource utilization.

China possesses abundant marine fishery resources, which play a vital role in the national economy. Achieving rapid and high-precision classification of underwater targets in complex aquatic environments is of significant importance for enhancing aquaculture intelligence and operational efficiency. To address the challenges of insufficient feature extraction and inefficient classifier parameter optimization in underwater image classification, this study proposes a classification method integrating local binary patterns (LBP), kernel principal component analysis (KPCA), and an improved sparrow search algorithm (SSA). The method first extracts image texture features using LBP and then applies KPCA for nonlinear dimensionality reduction. Subsequently, three optimization strategies—dynamic weighting, boundary contraction, and adaptive mutation—are introduced to enhance SSA, which is then employed to optimize the core parameters of the Support Vector Machine (SVM). Experiments were conducted on an underwater image dataset containing four types of targets: sea urchins, fish, rocks, and scallops. The results demonstrate that, compared with the traditional KPCA-SVM method, the integration of LBP features and the improved SSA increases classification accuracy from 55% to 94.37%, validating the effectiveness of the proposed approach in extracting underwater image features and optimizing classifier parameters. This provides technical support for improving the feasibility of automatic underwater target recognition in aquaculture applications.

The ocean archives massive, stable remote sensing datasets, and leveraging these data to achieve intelligent real-time recognition of marine organisms has become a core task in the field of marine remote sensing. However, in complex seabed environments, marine monitoring equipment is often constrained by limited computing power—this creates an urgent demand among oceanographers for detection algorithms with low computational complexity, which can be widely deployed on low-cost, simple marine remote sensing devices. To address this demand, this study proposes a deep learning-based algorithm for lightweight seabed organism detection efficiently (LSOD). This algorithm integrates Mamba and YOLO principles to enable efficient lightweight benthic organism detection. For LSOD’s neck, the original concatenation modules are improved, which efficiently aggregates feature layer information across backbone stages for cross-scale fusion. To further reduce the computational requirements of LSOD, a new detection head module based on group normalization and shared convolution operations is designed. These improvements maintain a reasonable computational load while enhancing the precision of the object detection network. EUDD tests indicate LSOD’s performance: the detection precision achieves 90.6% (sea cucumbers), 91.6% (sea urchins), and 93.5% (scallops). Comparisons with mainstream models confirm its superiority in detecting benthic organisms. This work is expected to provide new insights and approaches for intelligent remote sensing and analysis in marine ranches.

Sea urchin is always touted as a promising alternative marine source for dietary essential fatty acids. Often overlooked is that their lipid composition can vary significantly depending on the species and their feeding preferences. Understanding that every sea urchin species, together with their feeding behaviour, may offer unique nutritional benefits helps to optimise the utilisation of sea urchin as a reliable source of marine fatty acids. This study aimed to measure the gonad index, lipid content, and composition in the gonads of two sea urchin species live in coral reef and seagrass habitats in Malaysia. The gonad’s lipid was extracted using the Folch extraction method, followed by the esterification process before being analysed using GC-FID. The gonad index was calculated based on the percentage of gonads relative weight as a proportion of total body weight. The gonad indexes of both Diadema setosum (Leske, 1778) 6.74 ± 2.49% and Salmacis sphaeroides (Linnaeus, 1758) 6.68 ± 2.30% were found to be statistically indifferent (p&gt;0.05). Both D. setosum and S. sphaeroides had a negative allometric growth (b &lt; 3). The major saturated fatty acids found in both species were C16:0 and C14:0 while the major unsaturated fatty acids (UFAs) were C16:1 and C18:3. In the gonads of both species, n-6 UFAs were the most abundant, followed by n-9 and n-3 UFAs. In D. setosum, n-6 UFAs comprised 74.77%, n-9 UFAs 21.76%, and n-3 UFAs 3.47%. In contrast, S. sphaeroides had 52.13% n-6, 22.48% n-9, and a notably higher proportion of n-3 UFAs at 25.39%. S. sphaeroides lacked two types of fatty acids that were present in D. setosum, specifically C17:1 (heptadecenoic acid) and C20:1n-9 (gondoic acid). This study reveals the different composition of fatty acids in the gonads of D. setosum collected from coral reef areas and S. sphaeroides collected from seagrass areas of Malaysian water. Recognising these differences is crucial when evaluating sea urchins as a promising alternative source of healthy dietary fats.

Sea urchin is always touted as a promising alternative marine source for dietary essential fatty acids. Often overlooked is that their lipid composition can vary significantly depending on the species and their feeding preferences. Understanding that every sea urchin species, together with their feeding behaviour, may offer unique nutritional benefits helps to optimise the utilisation of sea urchin as a reliable source of marine fatty acids. This study aimed to measure the gonad index, lipid content, and composition in the gonads of two sea urchin species live in coral reef and seagrass habitats in Malaysia. The gonad’s lipid was extracted using the Folch extraction method, followed by the esterification process before being analysed using GC-FID. The gonad index was calculated based on the percentage of gonads relative weight as a proportion of total body weight. The gonad indexes of both Diadema setosum (Leske, 1778) 6.74 ± 2.49% and Salmacis sphaeroides (Linnaeus, 1758) 6.68 ± 2.30% were found to be statistically indifferent (p&gt;0.05). Both D. setosum and S. sphaeroides had a negative allometric growth (b &lt; 3). The major saturated fatty acids found in both species were C16:0 and C14:0 while the major unsaturated fatty acids (UFAs) were C16:1 and C18:3. In the gonads of both species, n-6 UFAs were the most abundant, followed by n-9 and n-3 UFAs. In D. setosum, n-6 UFAs comprised 74.77%, n-9 UFAs 21.76%, and n-3 UFAs 3.47%. In contrast, S. sphaeroides had 52.13% n-6, 22.48% n-9, and a notably higher proportion of n-3 UFAs at 25.39%. S. sphaeroides lacked two types of fatty acids that were present in D. setosum, specifically C17:1 (heptadecenoic acid) and C20:1n-9 (gondoic acid). This study reveals the different composition of fatty acids in the gonads of D. setosum collected from coral reef areas and S. sphaeroides collected from seagrass areas of Malaysian water. Recognising these differences is crucial when evaluating sea urchins as a promising alternative source of healthy dietary fats.