Effect of harvesting season and location on the microbial quality and community composition of the edible sea urchin (Echinus esculentus) gonads.

Despite the crucial role of microbial community composition in the quality and stability of seafood, little emphasis has been given to the microbiota profile of sea urchin gonads. This study investigates the microbial quality and community composition of sea urchin gonads (Echinus esculentus) as a function of harvesting season (autumn, winter, spring, and summer) and location (one site proximal to urban activity areas while the other is located in open water close to the coastline). Significant season-dependent variations were found in psychrotrophic and aerobic plate counts, with higher counts in summer, followed by autumn, spring, and winter. H2S-producing bacteria and Pseudomonas spp. counts were unaffected by harvesting season or location. Sea urchin gonad microbial composition proved resilient and dynamic, primarily shaped by seasonal variations, and minimally influenced by location. Winter and spring samples exhibited higher diversity than autumn and summer. Key genera like Pseudomonas, Psychromonas, Vibrio, Chryseobacterium, Shewanella, and Photobacterium varied seasonally. Pseudomonas, Vibrio, and Photobacterium are crucial in assessing microbial quality and safety due to their roles as specific spoilage organisms (SSOs) and, in some cases, human pathogens. Though relative abundances differed slightly between locations, harvesting location did not notably impact microbial community shaping in gonads. However, the results suggest that harvesting locations near areas with urban activity may lead to contamination with specific bacterial species, possibly due to water quality variations. These findings emphasize the importance of considering seasonality when evaluating sea urchin gonad microbial quality. Identifying key genera enhances insights into potential SSOs and human pathogens, enhancing food safety considerations in the consumption of raw or lightly processed sea urchin gonads and guiding the development of preservation methods to extend shelf life.

Detection of TALEN-mediated genome cleavage during the early embryonic stage of the starfish Patiria pectinifera.

BACKGROUND: Echinoderms have long been utilized as experimental materials to study the genetic control of developmental processes and their evolution. Among echinoderms, the molecular study of starfish embryos has received considerable attention across research topics such as gene regulatory network evolution and larval regeneration. Recently, experimental techniques to manipulate gene functions have been gradually established in starfish as the feasibility of genome editing methods was reported. However, it is still unclear when these techniques cause genome cleavage during the development of starfish, which is critical to understand the timeframe and applicability of the experiment during early development of starfish. RESULTS: We herein reported that gene functions can be analyzed by the genome editing method TALEN in early embryos, such as the blastula of the starfish Patiria pectinifera. We injected the mRNA of TALEN targeting rar, which was previously constructed, into eggs of P. pectinifera and examined the efficiency of genome cleavage through developmental stages from 6 to 48 hours post fertilization. CONCLUSION: The results will be key knowledge not only when designing TALEN-based experiments but also when assessing the results.

A Devonian crinoid with a diamond microlattice.

Owing to their remarkable physical properties, cellular structures, such as triply periodic minimal surfaces (TPMS), have multidisciplinary and multifunctional applications. Although these structures are observed in nature, examples of TPMS with large length scales in living organisms are exceedingly rare. Recently, microstructure reminiscent of the diamond-type TPMS was documented in the skeleton of the modern knobby starfish Protoreaster nodosus. Here we report a similar microlattice in a 385 Myr old crinoid Haplocrinites, which pushes back the origins of this highly ordered microstructure in echinoderms into the Devonian. Despite the low Mg2+/Ca2+ ratio of the 'calcite' Devonian sea, the skeleton of these crinoids has high-Mg content, which indicates strong biological control over biomineralogy. We suggest that such an optimization of trabecular arrangement additionally enriched in magnesium, which enhances the mechanical properties, might have evolved in these crinoids in response to increased predation pressure during the Middle Palaeozoic Marine Revolution. This discovery illustrates the remarkable ability of echinoderms, through the process of evolutionary optimization, to form a lightweight, stiff and damage-tolerant skeleton, which serves as an inspiration for biomimetic materials.

Evidence of introgression, ecological divergence and adaptation in Asterias sea stars.

Hybrid zones are important windows into the evolutionary dynamics of populations, revealing how processes like introgression and adaptation structure population genomic variation. Importantly, they are useful for understanding speciation and how species respond to their environments. Here, we investigate two closely related sea star species, Asterias rubens and A. forbesi, distributed along rocky European and North American coastlines of the North Atlantic, and use genome-wide molecular markers to infer the distribution of genomic variation within and between species in this group. Using genomic data and environmental niche modelling, we document hybridization occurring between northern New England and the southern Canadian Maritimes. We investigate the factors that maintain this hybrid zone, as well as the environmental variables that putatively drive selection within and between species. We find that the two species differ in their environmental niche breadth; Asterias forbesi displays a relatively narrow environmental niche while conversely, A. rubens has a wider niche breadth. Species distribution models accurately predict hybrids to occur within environmental niche overlap, thereby suggesting environmental selection plays an important role in the maintenance of the hybrid zone. Our results imply that the distribution of genomic variation in North Atlantic sea stars is influenced by the environment, which will be crucial to consider as the climate changes.

Genomic insights of evolutionary divergence and life history innovations in Antarctic brittle stars.

Understanding the drivers of evolutionary innovation provides a crucial perspective of how evolutionary processes unfold across taxa and ecological systems. It has been hypothesised that the Southern Ocean provided ecological opportunities for novelty in the past. However, the drivers of innovation are challenging to pinpoint as the evolutionary genetics of Southern Ocean fauna are influenced by Quaternary glacial-interglacial cycles, oceanic currents and species ecology. Here we examined the genome-wide single nucleotide polymorphisms of the Southern Ocean brittle stars Ophionotus victoriae (five arms, broadcaster) and O. hexactis (six arms, brooder). We found that O. victoriae and O. hexactis are closely-related species with interspecific gene flow. During the late Pleistocene, O. victoriae likely persisted in a connected deep water refugium and in situ refugia on the Antarctic continental shelf and around Antarctic islands; O. hexactis persisted exclusively within in situ island refugia. Within O. victoriae, contemporary gene flow linking to the Antarctic Circumpolar Current, regional gyres and other local oceanographic regimes was observed. Gene flow connecting West and East Antarctic islands near the Polar Front was also detected in O. hexactis. A strong association was detected between outlier loci and salinity in O. hexactis. Both O. victoriae and O. hexactis are associated with genome-wide increase in alleles at intermediate-frequencies; the alleles associated with this peak appear to be species specific, and these intermediate-frequency variants are far more excessive in O. hexactis. We hypothesise that the peak in alleles at intermediate frequencies could be related to adaptation in the recent past, linked to evolutionary innovations of increase in arm number and a switch to brooding from broadcasting, in O. hexactis.

Conservation and contrast in cell states of echinoderm ovaries.

Echinoderms produce functional gametes throughout their lifespan, in some cases exceeding 200 years. The histology and ultrastructure of echinoderm ovaries has been described but how these ovaries function and maintain the production of high-quality gametes remains a mystery. Here, we present the first single cell RNA sequencing data sets of mature ovaries from two sea urchin species (Strongylocentrotus purpuratus [Sp] and Lytechinus variegatus [Lv]), and one sea star species (Patiria miniata [Pm]). We find 14 cell states in the Sp ovary, 16 cell states in the Lv ovary and 13 cell states in the ovary of the sea star. This resource is essential to understand the structure and functional biology of the ovary in echinoderms, and better informs decisions in the utilization of in situ RNA hybridization probes selective for various cell types. We link key genes with cell clusters in validation of this approach. This resource also aids in the identification of the stem cells for prolonged and continuous gamete production, is a foundation for testing changes in the annual reproductive cycle, and is essential for understanding the evolution of reproduction of this important phylum.

Hyposalinity reduces coordination and adhesion of sea urchin tube feet.

Climate change will increase the frequency and intensity of low-salinity (hyposalinity) events in coastal marine habitats. Sea urchins are dominant herbivores in these habitats and are generally intolerant of salinity fluctuations. Their adhesive tube feet are essential for survival, effecting secure attachment and locomotion in high wave energy habitats, yet little is known about how hyposalinity impacts their function. We exposed green sea urchins (Strongylocentrotus droebachiensis) to salinities ranging from ambient (32‰) to severe (14‰) and assessed tube feet coordination (righting response, locomotion) and adhesion [disc tenacity (force per unit area)]. Righting response, locomotion and disc tenacity decreased in response to hyposalinity. Severe reductions in coordinated tube foot activities occurred at higher salinities than those that affected adhesion. The results of this study suggest moderate hyposalinities (24-28‰) have little effect on S. droebachiensis dislodgement risk and survival post-dislodgment, while severe hyposalinity (below 24‰) likely reduces movement and prevents recovery from dislodgment.

Extracellular Matrix of Echinoderms.

This review considers available data on the composition of the extracellular matrix (ECM) in echinoderms. The connective tissue in these animals has a rather complex organization. It includes a wide range of structural ECM proteins, as well as various proteases and their inhibitors. Members of almost all major groups of collagens, various glycoproteins, and proteoglycans have been found in echinoderms. There are enzymes for the synthesis of structural proteins and their modification by polysaccharides. However, the ECM of echinoderms substantially differs from that of vertebrates by the lack of elastin, fibronectins, tenascins, and some other glycoproteins and proteoglycans. Echinoderms have a wide variety of proteinases, with serine, cysteine, aspartic, and metal peptidases identified among them. Their active centers have a typical structure and can break down various ECM molecules. Echinoderms are also distinguished by a wide range of proteinase inhibitors. The complex ECM structure and the variety of intermolecular interactions evidently explain the complexity of the mechanisms responsible for variations in the mechanical properties of connective tissue in echinoderms. These mechanisms probably depend not only on the number of cross-links between the molecules, but also on the composition of ECM and the properties of its proteins.

Antitumor Properties of Matrikines of Different Origins: Prospects and Problems of Their Application.

Matrikines (MKs) can be a rich source of functional nutrition components and additional therapy, thereby contributing to human health care and reducing the risk of developing serious diseases, including cancer. Currently, functionally active MKs as products of enzymatic transformation by matrix metalloproteinases (MMPs) are used for various biomedical purposes. Due to the absence of toxic side effects, low species specificity, relatively small size, and presence of various targets at the cell membranes, MKs often exhibit antitumor properties and, therefore, are promising agents for antitumor combination therapy. This review summarizes and analyzes the current data on the antitumor activity of MKs of different origins, discusses the problems and prospects for their therapeutic use, and evaluates the experimental results of studying the antitumor properties of MKs from different echinoderm species generated with the help of a complex of proteolytic enzymes from red king crab Paralithodes camtschatica. Special attention is paid to the analysis of possible mechanisms of the antitumor action of various functionally active MKs, products of the enzymatic activity of various MMPs, and the existing problems for their use in antitumor therapy.

Analysis of the DNA-binding properties of Alx1, an evolutionarily conserved regulator of skeletogenesis in echinoderms.

Alx1, a homeodomain-containing transcription factor, is a highly conserved regulator of skeletogenesis in echinoderms. In sea urchins, Alx1 plays a central role in the differentiation of embryonic primary mesenchyme cells (PMCs) and positively regulates the transcription of most biomineralization genes expressed by these cells. The alx1 gene arose via duplication and acquired a skeletogenic function distinct from its paralog (alx4) through the exonization of a 41-amino acid motif (the D2 domain). Alx1 and Alx4 contain glutamine-50 paired-type homeodomains, which interact preferentially with palindromic binding sites in vitro. Chromatin immunoprecipitation sequencing (ChIP-seq) studies have shown, however, that Alx1 binds both to palindromic and half sites in vivo. To address this apparent discrepancy and explore the function of the D2 domain, we used an endogenous cis-regulatory module associated with Sp-mtmmpb, a gene that encodes a PMC-specific metalloprotease, to analyze the DNA-binding properties of Alx1. We find that Alx1 forms dimeric complexes on TAAT-containing half sites by a mechanism distinct from the well-known mechanism of dimerization on palindromic sites. We used transgenic reporter assays to analyze the functional roles of half sites in vivo and demonstrate that two sites with partially redundant functions are essential for the PMC-specific activity of the Sp-mtmmpb cis-regulatory module. Finally, we show that the D2 domain influences the DNA-binding properties of Alx1 in vitro, suggesting that the exonization of this motif may have facilitated the acquisition of new transcriptional targets and consequently a novel developmental function.

Cambrian edrioasteroid reveals new mechanism for secondary reduction of the skeleton in echinoderms.

Echinoderms are characterized by a distinctive high-magnesium calcite endoskeleton as adults, but elements of this have been drastically reduced in some groups. Herein, we describe a new pentaradial echinoderm, Yorkicystis haefneri n. gen. n. sp., which provides, to our knowledge, the oldest evidence of secondary non-mineralization of the echinoderm skeleton. This material was collected from the Cambrian Kinzers Formation in York (Pennsylvania, USA) and is dated as ca 510 Ma. Detailed morphological observations demonstrate that the ambulacra (i.e. axial region) are composed of flooring and cover plates, but the rest of the body (i.e. extraxial region) is preserved as a dark film and lacks any evidence of skeletal plating. Moreover, X-ray fluorescence analysis reveals that the axial region is elevated in iron. Based on our morphological and chemical data and on taphonomic comparisons with other fossils from the Kinzers Formation, we infer that the axial region was originally calcified, while the extraxial region was non-mineralized. Phylogenetic analyses recover Yorkicystis as an edrioasteroid, indicating that this partial absence of skeleton resulted from a secondary reduction. We hypothesize that skeletal reduction resulted from lack of expression of the skeletogenic gene regulatory network in the extraxial body wall during development. Secondary reduction of the skeleton in Yorkicystis might have allowed for greater flexibility of the body wall.

More than a simple epithelial layer: multifunctional role of echinoderm coelomic epithelium.

In echinoderms, the coelomic epithelium (CE) is reportedly the source of new circulating cells (coelomocytes) as well as the provider of molecular factors such as immunity-related molecules. However, its overall functions have been scarcely studied in detail. In this work, we used an integrated approach based on both microscopy (light and electron) and proteomic analyses to investigate the arm CE in the starfish Marthasterias glacialis during different physiological conditions (i.e., non-regenerating and/or regenerating). Our results show that CE cells share both ultrastructural and proteomic features with circulating coelomocytes (echinoderm immune cells). Additionally, microscopy and proteomic analyses indicate that CE cells are actively involved in protein synthesis and processing, and membrane trafficking processes such as phagocytosis (particularly of myocytes) and massive secretion phenomena. The latter might provide molecules (e.g., immune factors) and fluids for proper arm growth/regrowth. No stem cell marker was identified and no pre-existing stem cell was observed within the CE. Rather, during regeneration, CE cells undergo dedifferentiation and epithelial-mesenchymal transition to deliver progenitor cells for tissue replacement. Overall, our work underlines that echinoderm CE is not a "simple epithelial lining" and that instead it plays multiple functions which span from immunity-related roles as well as being a source of regeneration-competent cells for arm growth/regrowth.

The Link between Autotomy and CNS Regeneration: Echinoderms as Non-Model Species for Regenerative Biology.

Achieving regeneration of the central nervous system (CNS) is a major challenge for regenerative medicine. The inability of mammals to regrow a severed CNS contrasts with the amazing regenerative powers of their deuterostome kin, the echinoderms. Rapid CNS regeneration from a specialized autotomy plane in echinoderms presents a highly tractable and suitable non-model system for regenerative biology and evolution. Starfish arm autotomy triggers mass cell migration and local proliferation, facilitating rapid CNS regeneration. Many regeneration events in nature are preceded by autotomy and there are striking parallels between autotomy and regeneration in starfish and lizards. Comparison of these systems holds promise to provide insight into regeneration deficiency in higher vertebrates and to uncover evolutionarily conserved deuterostome-chordate regenerative processes. This will help identify mechanisms that may be present but inactive in higher vertebrates to address the problem of their poor regenerative capacities and the challenge to achieve CNS repair and regrowth.

Ciliary photoreceptors in sea urchin larvae indicate pan-deuterostome cell type conservation.

BACKGROUND: The evolutionary history of cell types provides insights into how morphological and functional complexity arose during animal evolution. Photoreceptor cell types are particularly broadly distributed throughout Bilateria; however, their evolutionary relationship is so far unresolved. Previous studies indicate that ciliary photoreceptors are homologous at least within chordates, and here, we present evidence that a related form of this cell type is also present in echinoderm larvae. RESULTS: Larvae of the purple sea urchin Strongylocentrotus purpuratus have photoreceptors that are positioned bilaterally in the oral/anterior apical neurogenic ectoderm. Here, we show that these photoreceptors express the transcription factor Rx, which is commonly expressed in ciliary photoreceptors, together with an atypical opsin of the GO family, opsin3.2, which localizes in particular to the cilia on the cell surface of photoreceptors. We show that these ciliary photoreceptors express the neuronal marker synaptotagmin and are located in proximity to pigment cells. Furthermore, we systematically identified additional transcription factors expressed in these larval photoreceptors and found that a majority are orthologous to transcription factors expressed in vertebrate ciliary photoreceptors, including Otx, Six3, Tbx2/3, and Rx. Based on the developmental expression of rx, these photoreceptors derive from the anterior apical neurogenic ectoderm. However, genes typically involved in eye development in bilateria, including pax6, six1/2, eya, and dac, are not expressed in sea urchin larval photoreceptors but are instead co-expressed in the hydropore canal. CONCLUSIONS: Based on transcription factor expression, location, and developmental origin, we conclude that the sea urchin larval photoreceptors constitute a cell type that is likely homologous to the ciliary photoreceptors present in chordates.

Glycosylation at an evolutionary nexus: the brittle star Ophiactis savignyi expresses both vertebrate and invertebrate N-glycomic features.

Echinoderms are among the most primitive deuterostomes and have been used as model organisms to understand chordate biology because of their close evolutionary relationship to this phylogenetic group. However, there are almost no data available regarding the N-glycomic capacity of echinoderms, which are otherwise known to produce a diverse set of species-specific glycoconjugates, including ones heavily modified by fucose, sulfate, and sialic acid residues. To increase the knowledge of diversity of carbohydrate structures within this phylum, here we conducted an in-depth analysis of N-glycans from a brittle star (Ophiactis savignyi) as an example member of the class Ophiuroidea. To this end, we performed a multi-step N-glycan analysis by HPLC and various exoglyosidase and chemical treatments in combination with MALDI-TOF MS and MS/MS. Using this approach, we found a wealth of hybrid and complex oligosaccharide structures reminiscent of those in higher vertebrates as well as some classical invertebrate glycan structures. 70% of these N-glycans were anionic, carrying either sialic acid, sulfate, or phosphate residues. In terms of glycophylogeny, our data position the brittle star between invertebrates and vertebrates and confirm the high diversity of N-glycosylation in lower organisms.

Conserved regulatory state expression controlled by divergent developmental gene regulatory networks in echinoids.

Evolution of the animal body plan is driven by changes in developmental gene regulatory networks (GRNs), but how networks change to control novel developmental phenotypes remains, in most cases, unresolved. Here, we address GRN evolution by comparing the endomesoderm GRN in two echinoid sea urchins, Strongylocentrotus purpuratus and Eucidaris tribuloides, with at least 268 million years of independent evolution. We first analyzed the expression of twelve transcription factors and signaling molecules of the S. purpuratus GRN in E. tribuloides embryos, showing that orthologous regulatory genes are expressed in corresponding endomesodermal cell fates in the two species. However, perturbation of regulatory genes revealed that important regulatory circuits of the S. purpuratus GRN are significantly different in E. tribuloides For example, mesodermal Delta/Notch signaling controls exclusion of alternative cell fates in E. tribuloides but controls mesoderm induction and activation of a positive feedback circuit in S. purpuratus These results indicate that the architecture of the sea urchin endomesoderm GRN evolved by extensive gain and loss of regulatory interactions between a conserved set of regulatory factors that control endomesodermal cell fate specification.

Coelomocyte replenishment in adult Asterias rubens: the possible ways.

The origin of cells involved in regeneration in echinoderms remains an open question. Replenishment of circulatory coelomocytes-cells of the coelomic cavity in starfish-is an example of physiological regeneration. The coelomic epithelium is considered to be the main source of coelomocytes, but many details of this process remain unclear. This study examined the role of coelomocytes outside circulation, named marginal coelomocytes and small undifferentiated cells of the coelomic epithelium in coelomocyte replenishment in Asterias rubens. A qualitative and quantitative comparison of circulatory and marginal coelomocytes, as well as changes of circulatory coelomocyte concentrations in response to injury at different physiological statuses, was analysed. The presence of cells morphologically similar to coelomocytes in the context of coelomic epithelium was evaluated by electron microscopy. The irregular distribution of small cells on the surface and within the coelomic epithelium was demonstrated and the origin of small undifferentiated cells and large agranulocytes from the coelomic epithelium was suggested. Two events have been proposed to mediate the replenishment of coelomocytes in the coelom: migration of mature coelomocytes of the marginal cell pool and migration of small undifferentiated cells of the coelomic epithelium. The proteomic analysis of circulatory coelomocytes, coelomic epithelial cells and a subpopulation of coelomic epithelial cells, enriched in small undifferentiated cells, revealed proteins that were common and specific for each cell pool. Among these molecules were regulatory proteins, potential participants of regenerative processes.

A new subfamily of ionotropic glutamate receptors unique to the echinoderms with putative sensory role.

Chemosensation is a critical signalling process in animals and especially important in sea cucumbers, a group of ecologically and economically important marine echinoderms (class Holothuroidea), which lack audio and visual organs and rely on chemical sensing for survival, feeding and reproduction. The ionotropic receptors are a recently identified family of chemosensory receptors in insects and other protostomes, related to the ionotropic glutamate receptor family (iGluR), a large family of membrane receptors in metazoan. Here we characterize the echinoderm iGluR subunits and consider their possible role in chemical communication in sea cucumbers. Sequence similarity searches revealed that sea cucumbers have in general a higher number of iGluR subunits when compared to other echinoderms. Phylogenetic analysis and sequence comparisons revealed GluH as a specific iGluR subfamily present in all echinoderms. Homologues of the vertebrate GluA (aka α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA), GluK (aka kainate) and GluD (aka delta) were also identified. The GluN (aka N-methyl-d-aspartate, NMDA) as well as the invertebrate deuterostome subfamily GluF (aka phi) are absent in echinoderms. The echinoderm GluH subfamily shares conserved structural protein organization with vertebrate iGluRs and the ligand binding domain (LBD) is the most conserved region; genome analysis indicates evolution via lineage and species-specific tandem gene duplications. GluH genes (named Grih) are the most highly expressed iGluRs subunit genes in tissues in the sea cucumber Holothuria arguinesis, with Griha1, Griha2 and Griha5 exclusively expressed in tentacles, making them candidates to have a chemosensory role in this species. The multiple GluH subunits may provide alternative receptor assembly combinations, thus expanding the functional possibilities and widening the range of compounds detected during aggregation and spawning in echinoderms.

Run and hide: visual performance in a brittle star.

Spatial vision was recently reported in a brittle star, Ophiomastix wendtii, which lacks discrete eyes, but little is known about its visual ecology. Our aim was to better characterize the vision and visual ecology of this unusual visual system. We tested animal orientation relative to vertical bar stimuli at a range of angular widths and contrasts, to identify limits of angular and contrast detection. We also presented dynamic shadow stimuli, either looming towards or passing the animal overhead, to test for potential defensive responses. Finally, we presented animals lacking a single arm with a vertical bar stimulus known to elicit a response in intact animals. We found that O. wendtii orients to large (≥50 deg), high-contrast vertical bar stimuli, consistent with a shelter-seeking role and with photoreceptor acceptance angles estimated from morphology. We calculate poor optical sensitivity for individual photoreceptors, and predict dramatic oversampling for photoreceptor arrays. We also report responses to dark stimuli moving against a bright background - this is the first report of responses to moving stimuli in brittle stars and suggests additional defensive uses for vision in echinoderms. Finally, we found that animals missing a single arm orient less well to static stimuli, which requires further investigation.

Current Progress in Lipidomics of Marine Invertebrates.

Marine invertebrates are a paraphyletic group that comprises more than 90% of all marine animal species. Lipids form the structural basis of cell membranes, are utilized as an energy reserve by all marine invertebrates, and are, therefore, considered important indicators of their ecology and biochemistry. The nutritional value of commercial invertebrates directly depends on their lipid composition. The lipid classes and fatty acids of marine invertebrates have been studied in detail, but data on their lipidomes (the profiles of all lipid molecules) remain very limited. To date, lipidomes or their parts are known only for a few species of mollusks, coral polyps, ascidians, jellyfish, sea anemones, sponges, sea stars, sea urchins, sea cucumbers, crabs, copepods, shrimp, and squid. This paper reviews various features of the lipid molecular species of these animals. The results of the application of the lipidomic approach in ecology, embryology, physiology, lipid biosynthesis, and in studies on the nutritional value of marine invertebrates are also discussed. The possible applications of lipidomics in the study of marine invertebrates are considered.