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During scientific technical dives in a marine animal forest (MAF) environment, the nudibranch Dondice trainitoi Furfaro & Mariottini 2020 was recorded on a rocky bottom at 50 m depth in the Salento Peninsula, Southern Italy, Eastern Mediterranean Sea. Further in situ explorations and broad bibliographic research within both the scientific and grey literature revealed that D. trainitoi is widely distributed across the Mediterranean Sea, despite what was previously known. Herein are the first records for the Adriatic Sea and the Apulia region of Italy, together with the deepest record of this species. An analysis of collected samples and both in situ and laboratory photographs of the hydrozoan colonies associated with D. trainitoi revealed its ecology and trophic behaviour; we conclude that the hydrozoan Obelia bidentata Clark, 1875 is its preferred prey, but that it also feeds on the athecate hydroid Eudendrium glomeratum Picard, 1952. These findings shed some light on the little-known ecology and distribution, on both a geographical and a bathymetric scale, of this species, which are fundamental to increasing knowledge on Mediterranean biodiversity and its ecosystem functions. [ABSTRACT FROM AUTHOR]

The organization of DNA into nucleosomes is a ubiquitous and ancestral feature that was once thought to be exclusive to the eukaryotic domain of life. Intriguingly, several representatives of the Nucleocytoplasmic Large DNA Viruses (NCLDV) encode histone-like proteins that in Melbournevirus were shown to form nucleosome-like particles. Medusavirus medusae (MM), a distantly related giant virus, encodes all four core histone proteins and, unique amongst most giant viruses, a putative acidic protein with two domains resembling eukaryotic linker histone H1. Here, we report the structure of nucleosomes assembled with MM histones and highlight similarities and differences with eukaryotic and Melbournevirus nucleosomes. Our structure provides insight into how variations in histone tail and loop lengths are accommodated within the context of the nucleosome. We show that MM-histones assemble into tri-nucleosome arrays, and that the putative linker histone H1 does not function in chromatin compaction. These findings expand our limited understanding of chromatin organization by virus-encoded histones. Some large DNA viruses encode histone-like proteins similar to those in eukaryotes, which organize DNA into nucleosome-like particles. Here the authors find that Medusavirus histones form nucleosomes and arrays, but its unique linker histone H1 does not interact with chromatin. This reveals insights into how viruses organize their genetic material. [ABSTRACT FROM AUTHOR]

This article discusses the association between argonauts, a group of octopods, and various substrates in the ocean. The study used images shared by recreational divers on social media to quantify the diversity of substrates used by argonauts for movement. The images showed that argonauts were attached to plastic waste, vegetal debris, and pelagic animals, with gelatinous plankton being the most abundant substrate. The study also observed accompanying fauna sharing the same substrate with the argonauts. The findings highlight the value of citizen science and the use of high-quality images obtained during blackwater dives for studying the behavior and interactions of oceanic pelagic organisms. [Extracted from the article]

Introduction: Upside-down jellyfish (Cassiopea sp.) are highly tolerant to multiple abiotic stressors, including fluctuating temperatures associated with shallow marine habitats. This resilience may underlie the ability of Cassiopea sp. to inhabit a wide variety of tropical habitats across the globe. Additionally, Cassiopea sp. are marked by a conspicuous array of appendage coloration; individual medusae vary in the hue and number of oral appendages, which are often strikingly blue. The function of this coloration is not understood. We aimed to understand how extrinsic (temperature, location) and intrinsic (host color) factors may shape thermal tolerance. Methods: Adult Cassiopea xamachana were collected from two sites that vary in daily temperature range within the Florida Keys and were subjected to acute lethal heat stress. To quantify a whole-organism response to heat, we measured changes in bell pulsation, which likely plays a role in feeding, oxygen exchange, and symbiont uptake. Finally, color morphs were acclimated at either ambient (26°C) or elevated (33°C) temperatures. Results: C. xamachana from two locations that vary in thermal range do not exhibit different responses to heat, suggesting that temperature fluctuations do not prime individuals for higher thermal tolerance. Additionally, C. xamachana with blue appendages survived significantly higher temperatures and exhibited less change in bell pulsation rates compared to non-blue individuals. We found that acclimation at 33°C, as well as appendage color in each treatment, led to higher survival under acute heat stress. Discussion: These findings highlight the importance of temperature and coloration in Cassiopea xamachana resilience during heat stress. [ABSTRACT FROM AUTHOR]

The sporophytes of moss plants are dependent on the gametophytes for both photosynthesis and water, which makes conducting cells (hydroids and leptoids) an important part of the sporophyte anatomy. A previous study found that Physcomitrium pyriforme, which has shorter sporophytes, had higher rates of water transport than Funaria hygrometrica, which has taller sporophytes. The aim of this study is to test for differences in the conducting cell anatomy between these two moss species, which could be responsible for differences in water transport rates. We used histology methods to fix, embed, and section sporophyte seta and then quantified the numbers and sizes of the conducting cells. The results revealed that leptoids comprise a higher proportion of the conducting cell area in P. pyriforme, while hydroids comprise more of the conducting cell area in F. hygrometrica. These results point toward the leptoids playing a role in water transport in the moss sporophyte. [ABSTRACT FROM AUTHOR]

The family Eirenidae is one of the major taxa of the order Leptothecata, comprising approximately 80 species from ten genera. In this study, taxonomic investigations, including morphological observations and molecular 16S phylogenetic analyses, were conducted on unknown Eirenidae specimens collected off the coast of Iwaki, Fukushima Prefecture, eastern Japan, in June 2022. The specimens had the following morphological characteristics: marginal warts and tentacular bulbs with lateral cirri and without adaxial papillae, a mouth with simple lips, four simple radial canals, and eight statocysts common to the genus Eutima. However, this species can be distinguished from other species of Eutima by the number of tentacles, number and shape of marginal warts, position of the gonads, and gastric peduncle length. Moreover, the monophyly of the species was evident in the 16S rRNA phylogenetic tree (as indicated by the high bootstrap value of 100%), thereby supporting the validity of the new species. Based on these results, we describe it as a new species, Eutima onahamaensis, for taxonomic stabilization. We also made detailed observations of the morphology and molecular phylogenetic analyses of one of the species newly recorded in Japan: Eutima diademata. A comparative table of the primary diagnostic characteristics of Eutima has been provided. This study provided taxonomic keys for identifying species in the genus Eutima. [ABSTRACT FROM AUTHOR]

Southern Ocean zooplankton provide globally significant ecosystem services through their role in carbon sequestration, nutrient cycling and food webs. However, the remote and extreme nature of the Southern Ocean creates significant logistical difficulties for studying zooplankton all year round. Here, for the first time in the Southern Ocean, we present the seasonal occurrence of the zooplankton assemblage in the Northeast Scotia Sea using a sediment trap deployed throughout 2018 (P3 observation site, 52.80˚ S, 40.14˚ W). Results show that copepods and pteropods dominated trap abundance, representing 25.0–68.3% and 13.4–72.5% respectively, followed by amphipods (1.0–7.2%) and hydrozoa (0.2–15.6%). The dominant signal in copepods was consistent with previous observations using traditional (net) sampling methods while the relative contribution of pteropods, amphipods and hydrozoa was increased in our trap. Further, zooplankton showed taxon-specific seasonal signals, with a relatively high number of individuals throughout winter, including an increase in hydrozoa occurrences. This observation highlights the importance of zooplankton as source of nutrition for the benthic community in the winter. Our data reiterate the utility of sediment traps for observing zooplankton in remote locations and sampling specific taxa that might be otherwise understudied. [ABSTRACT FROM AUTHOR]

The introduction of non-indigenous species (NIS) to exotic habitats can have tremendous impacts on native biodiversity, food webs, and ecosystem services. One globally distributed aquatic NIS is the hydrozoan Craspedacusta sowerbii Lankester, 1880. The species' northern distribution boundary in North America is situated in British Columbia (BC), Canada. It is thus of paramount interest to understand its ecology in this warming invaded habitat, allowing for insights into other regions. Specimens of the genus Craspedacusta have been reported in 34 freshwater systems since August 1990. These reported locations are generally shallow (<10 m), most often of natural origin, and have a small surface area (<0.1 km2). We observed an exponential trend of medusa observations from 1990 till the end of the 2020s. The first seasonal records are in July and the latest in October, with peak sightings reported in August and September. After 2012, regional temperature anomalies during July and August were mostly positive, which overlaps with the period of the majority of reported C. sowerbii sightings. Until this day, all examined medusae are males. [ABSTRACT FROM AUTHOR]

The red macroalga Gracilaria parvispora is an introduced species in the Mexican Pacific. To date, there are no published studies on its sessile epibionts, including the hydrozoans and bryozoans, which are the dominant epibionts on macrophytes and of significant biological and economic interest.This study provides insight into the faunal diversity of hydroids growing on G. parvispora. A total of 185 thalli from both herbarium specimens and field samples collected from five sites in La Paz Bay were revised. Each thallus size and the presence of hydroid epibionts in each thallus region were registered. Eight different hydrozoan taxa were growing on the red macroalgae, including the first recorded observation of Obelia oxydentata in the Gulf of California. The sizes of the collected thalli were mostly under 7.0 cm, the maximum number of taxa per thallus was three and the thallus region containing the highest number of epibionts was in the middle. Significant differences were observed amongst the lengths of thalli with and without epibionts. The thalli with epibionts were larger than the thalli without epibionts. Similarly, significant differences were observed amongst the months. The pair-wise test revealed that each month exhibited distinctive epibiont taxa when compared to the others. This study highlights the lack of information on these associations. Further research is needed to understand whether introduced macroalgae can bring non-native epibiont species to an area.

Gelatinous zooplankton constitutes a polyphyletic group with a convergent evolutionary history and poorly known biogeographical patterns. In the Gulf of Mexico, a region with complex geological, hydrological, and biotic histories, the study of this group has been limited to taxonomical and ecological aspects. In this study, we implemented a track analysis to identify distributional patterns of gelatinous zooplankton in the Gulf of Mexico and adjacent waters based on a dataset of 6067 occurrence records corresponding to Hydrozoa, Scyphozoa, Cubozoa, Ctenophora, Chaetognatha, Thaliacea, and Appendicularia. Information was compiled from the Global Biodiversity Facility Information (GBIF) and Ocean Biodiversity Information System (OBIS) databases and peer-reviewed literature. Individual tracks were constructed by joining the minimum distance between the occurrence localities of each taxon using a minimum spanning tree algorithm. We identified generalized tracks using parsimony analysis of endemicity with progressive character elimination (PAE-PCE). The areas where different generalized tracks overlapped were considered to represent panbiogeographical nodes. Seven generalized tracks (two with nested patterns) and six panbiogeographical nodes were recognized, mainly in neritic zones. The distributional patterns of gelatinous zooplankton allowed us to identify four biogeographic areas, supporting previously proposed biogeographic schemes. Gelatinous zooplankton in the Gulf of Mexico showed a convergent spatial distribution that can be explained by vicariant and dispersal events. The historical biogeography of the gelatinous biotas of the Gulf of Mexico has been little studied compared to ecological approaches, and the lack of integrative studies considering historical patterns is evident. This type of research is fundamental to understanding the evolutionary history of natural resources from a spatial perspective, identifying sites of biodiversity and endemism, and establishing a biogeographic baseline of the region for further studies. [ABSTRACT FROM AUTHOR]

Two types of edible jellyfish, namely ‘ball-type’ and ‘white-type’, were reported to be commercially harvested respectively from the southeast and northwest coasts of Sri Lanka, but their taxonomic identity was unknown. Therefore, medusae collected in the ‘Waya-jel-Survey’, together with specimens from museums, were examined, comparing their morphomeristic data with information from the literature. As per results, the ‘ball-type’ and ‘white-type’ jellyfish species were recognized respectively as Crambionella orsini (Vanhöffen 1888) and Lobonemoides gracilis Light 1914 for the first time from Sri Lanka, with a detailed account of morphological features. Among the four valid species of the genus Crambionella, C. orsini is distinguished by the presence of 16 velar lappets per octant, without tubercles. The two congeners of L. gracilis, namely L. robustus Stiasny 1920 and L. sewelli Rao 1931, were synonymized to L. gracilis, making Lobonemoides monospecific, thus L. gracilis is recognized by the presence of papillae on the exumbrella; 1–6 elongated velar lappets between two successive rhopalia; and the window-like openings and long, spindle-shaped appendages on the oral arms. Likewise, the present study re-describes C. orsini and L. gracilis providing a basic component for efficient management of jellyfish fishery resources in Sri Lanka as well as in other Asian countries. [ABSTRACT FROM AUTHOR]

Cilia are widely present in metazoans and have various sensory and motor functions, including collection of particles through feeding currents in suspensivorous animals. Suspended particles occur at low densities and are too small to be captured individually, and therefore must be concentrated. Animals that feed on these particles have developed different mechanisms to encounter and capture their food. These mechanisms occur in three phases: (i) encounter; (ii) capture; and (iii) particle handling, which occurs by means of a cilia‐generated current or the movement of capturing structures (e.g. tentacles) that transport the particle to the mouth. Cilia may be involved in any of these phases. Some cnidarians, as do other suspensivorous animals, utilise cilia in their feeding mechanisms. However, few studies have considered ciliary flow when examining the biomechanics of cnidarian feeding. Anthozoans (sessile cnidarians) are known to possess flow‐promoting cilia, but these are absent in medusae. The traditional view is that jellyfish capture prey only by means of nematocysts (stinging structures) and mucus, and do not possess cilia that collect suspended particles. Herein, we first provide an overview of suspension feeding in invertebrates, and then critically analyse the presence, distribution, and function of cilia in the Cnidaria (mainly Medusozoa), with a focus on particle collection (suspension feeding). We analyse the different mechanisms of suspension feeding and sort them according to our proposed classification framework. We present a scheme for the phases of pelagic jellyfish suspension feeding based on this classification. There is evidence that cilia create currents but act only in phases 1 and 3 of suspension feeding in medusozoans. Research suggests that some scyphomedusae must exploit other nutritional sources besides prey captured by nematocysts and mucus, since the resources provided by this diet alone are insufficient to meet their energy requirements. Therefore, smaller particles and prey may be captured through other phase‐2 mechanisms that could involve ciliary currents. We hypothesise that medusae, besides capturing prey by nematocysts (present in the tentacles and oral arms), also capture small particles with their cilia, therefore expanding their trophic niche and suggesting reinterpretation of the trophic role of medusoid cnidarians as exclusively plankton predators. We suggest further study of particle collection by ciliary action and its influence on the biomechanics of jellyfishes, to expand our understanding of the ecology of this group. [ABSTRACT FROM AUTHOR]

Gelatinous zooplankton are essential components of healthy ecosystems. Given their characteristic life cycle, ecological aspects and adaptability to a variety of oceanic conditions, these organisms are considered indicators of climate change, having particular advantages relative to other taxa. Citizen science initiatives are becoming increasingly frequent, providing data that are otherwise difficult to collect and interesting results for different taxa worldwide, allowing for example the detection of new occurrences. The ongoing citizen science program GelAvista, running since 2016, gathers data reported by observers on jellyfish occurrences in Portuguese waters, in the north-eastern Atlantic. The program has enhanced the knowledge of these organisms, providing data on biodiversity, and the dynamics of their distribution and abundance. Particular sightings of hydromedusae were received through GelAvista for mainland Portugal, close to the Tagus River, in the Lisbon Bay region. The species was morphologically and molecularly identified as Odessia maeotica, comprising its first reported occurrence in the Lisbon Bay. The details on the occurrence of the species are provided and discussed given the current knowledge of the species. [ABSTRACT FROM AUTHOR]

A new species of the amphipod family Stenothoidae found living in association with tubulariid hydroids in British Columbia, Canada is described. Stenula traudlae sp. nov. , which has a rounded naked telson, a rounded posterodistal tooth on Ep3, and a heavily spinose P5, is described morphologically. We also include an updated key to world species of Stenula s.l. Associations of amphipods with tubulariids and other small hosts are discussed. [ABSTRACT FROM AUTHOR]

A crucial first step in managing marine non-indigenous species (NIS) that pose a threat to native species, habitats or ecosystems is for countries to update their NIS lists. In the Mediterranean region, efforts to update these lists vary greatly from country to country. There is a notable disparity between the northern and southern coasts of this basin, which warrants attention to ensure a comprehensive assessment of the management and dissemination of NIS along the Mediterranean coasts. In this context, a rapid assessment survey was carried out along the Tunisian coasts in five marinas: Bizerte, Gammarth, Hammamet, Port El Kantaoui and Cap Monastir. NIS belonging to the five sessile macrozoobenthic groups Ascidiacea, Bryozoa, Porifera, Hydrozoa and Polychaeta in different substrata of these marina habitats were surveyed in May and December 2019. Here we report a total of twenty NIS and cryptogenic species with six new records in Tunisian marinas: Phallusia nigra Savigny, 1816; Clavelina oblonga Herdman, 1880; Ciona robusta Hoshino & Tokioka, 1967; Didemnum cf. vexillum Kott, 2002; Botrylloides cf. niger Herdman, 1886 and Bugula stolonifera (Ryland, 1960). Our findings suggest that it is important to monitor buoys when trying to detect NIS and cryptogenic species. [ABSTRACT FROM AUTHOR]

Abstract Freshwater jellyfish (= limnic medusa‐budding hydrozoans, FWJ) are a small group of cnidarians found on all continents except Antarctica in temperate to tropical latitudes. Members of this group belong primarily to three genera: Astrohydra, Craspedacusta, and Limnocnida. While Astrohydra and Limnocnida are typically restricted to the islands of Japan, Africa, and the Indian subcontinent, one species or potential species complex, Craspedacusta sowerbii, became globally invasive. Despite research going back about one‐and‐a‐half centuries, little is known about their phylogeny and ecology compared to marine jellyfish. Recent species distribution modelling, however, showed that by 2050, C. sowerbii will potentially extend their distribution ranges due to global warming to high‐latitude ecosystems and be present (medusa stage) for an extended time in the seasonal limnic production cycle. An increase in their relative ecological importance with temporal and spatial spreading is hypothesised. Only recently, it has been shown that the trophic roles of polyps and medusae and their prey overlap with other ecosystem members. In addition, medusa behaviour may cause trophic cascades and alter vertical nutrient distributions. However, polyps and other benthic life cycle stages are understudied. In globally, changing freshwater ecosystems that may become more accommodating for FWJ, an improved understanding of their population biology and ecosystem ecology is urgently needed. In this integrative review, we, therefore, explore reasons for the hampered historical research progress, contrast developments with those of marine cnidarians, compile and publish alongside an extensive and unprecedented literature database, and formulate avenues for future directions in FWJ research.

Hydractinia symbiolongicarpus is a pioneering model organism for stem cell biology, being one of only a few animals with adult pluripotent stem cells (known as i-cells). However, the unavailability of a chromosome-level genome assembly has hindered a comprehensive understanding of global gene regulatory mechanisms underlying the function and evolution of i-cells. Here, we report the first chromosome-level genome assembly of H. symbiolongicarpus (HSymV2.0) using PacBio HiFi long-read sequencing and Hi-C scaffolding. The final assembly is 483 Mb in total length with 15 chromosomes representing 99.8% of the assembly. Repetitive sequences were found to account for 296 Mb (61%) of the total genome; we provide evidence for at least two periods of repeat expansion in the past. A total of 25,825 protein-coding genes were predicted in this assembly, which include 93.1% of the metazoan Benchmarking Universal Single-Copy Orthologs (BUSCO) gene set. 92.8% (23,971 genes) of the predicted proteins were functionally annotated. The H. symbiolongicarpus genome showed a high degree of macrosynteny conservation with the Hydra vulgaris genome. This chromosome-level genome assembly of H. symbiolongicarpus will be an invaluable resource for the research community that enhances broad biological studies on this unique model organism.

AbstractThe species Monoserius pennarius (Linnaeus, 1758), is particularly abundant in the tropical Indo-West Pacific east of Sri Lanka, yet very limited genetic information exists for this species. Here, we report the assembled-linear mitochondrial genome of M. pennarius collected from the East China Sea. The 15,197 bp mitogenome contains 13 protein-coding genes (PCGs), two tRNA genes, and two rRNA genes. Notably, the gene order in this mitogenome differs from that of other hydrozoans within the same taxonomic order. Phylogenetic analysis, based on 13 concatenated mitochondrial PCGs, recovered M. pennarius as a sister of Nemalecium lighti (Hargitt, 1924), outside the other Leptothecata hydrozoans, suggesting paraphyly of Leptothecata. The mitogenome of M. pennarius, serving as the first publicly available for the family Aglaopheniidae, holds foreseeable value for investigating Leptothecata evolution.

In the present work, we study the effect of different stimuli (living preys, its homogenate, and reduced glutathione (GSH)) on the discharge of desmonemes in the freshwater cnidarian, Hydra plagiodesmica (Dioni, 1968) (Cnidaria: Hydrozoa). Once confirmed their stimulatory effect, we choose GSH to analyze the relevance of Ca2+, the probable identity of the sensory receptor molecule, and the specific signalling pathway driving the discharge mechanism. Our results show that not only mechanical, but also chemical stimuli by itself may stimulate the discharge of desmonemes. Using calcium chelators, we verify that the discharge mechanism triggered by GSH is dependent on calcium. By mean of drugs that inhibit proteins pertaining to canonical signalling pathways, including GPCRs, we show that GSH causes the influx of Ca2+ via L-type voltage sensitive calcium channel (VGCC), and its release by mean of endoplasmic reticulum calcium channels. Moreover, our results suggest that the putative receptor for GSH is a GPCR coupled to Gq, which produces IP3 and Ca2+ as second messengers. Finally, we show that the genome of Hydra vulgaris (Pallas, 1766) predicts the existence of the different subunits of L-type VGCC, showing a high level of conservation when compared with other groups of Metazoa. [ABSTRACT FROM AUTHOR]

Three previously unknown species of Hydroidomedusa are described from plankton samples collected during oceanographic cruises undertaken along the coast of China. The Anthomedusae Ectopleura dongshanensis Xu, Chen & Chang sp. n. and Ectopleura brevinema Xu, Chen & Wang sp. n. were collected in Dongshan Bay, and the Leptomedusae species Eirene globogonia Xu & Chen sp. n. was found in the shallow waters of Hainan Island. All new species are described and illustrated here. The species Eirene chiaochowensis (Kao, Li , Chang & Li , 1958) stat. rev. is revised to a valid species. Keys to known species of the genera Ectopleura and Eirene are provided. All specimens were deposited at the Third Institute of Oceanography, China. [ABSTRACT FROM AUTHOR]

Some hydrozoan species are known for their high adaptability and dormancy ability, e.g., Cladonema species, which are also promising model organisms. Since salinity affects the development and distribution of hydrozoan species, it is important to get further understanding of salinity tolerance and dormancy ability of Cladonema species. Cladonema digitatum is a cryptic species and is discovered only in artificial environments. In this study, multiple experiments have been conducted to determine how salinity affects the development of C. digitatum polyps and medusae, to describe the dormancy and recovery of the C. digitatum polyps, and to find the possible prevention and disposal protocol for the occurrence of Cladonema in artificial environments. As results, salinity range of 35–40 ppt was optimal for C. digitatum polyps, while C. digitatum medusae lived best in 30–35 ppt; C. digitatum would form menonts at 15, 50–60 ppt, revive and change their survival strategies after salinity upturned to 35 ppt, which could enhance their tolerance and adaptability. Cladonema digitatum medusae also showed different death rates when faced with sharp hypersaline and hyposaline stress. In summary, this research provided ecological information about salinity range and dormancy ability of C. digitatum, which not only facilitated tracing the wild habitats of the C. digitatum, but also provided the theoretical basic of elimination and prevention of Cladonema species intrusion and breeding conservation in the laboratory. [ABSTRACT FROM AUTHOR]

Simple Summary: The genus Craspedacusta comprises invasive freshwater jellyfish species present in all continents except Antarctica. Due to the morphological plasticity of the medusa stage, the number of species in the genus Craspedacusta is still disputed. Here, we shed new light on the distribution of the genetic lineages of these non-native species across the Italian peninsula, Sicily, and Sardinia. Since the first Italian record in 1946 and up to the last available review in 2017, Craspedacusta medusae were reported in 40 Italian water bodies. In the present study, we report 21 new records of Craspedacusta medusae presence since its latest finding in 2017. Furthermore, we present results of the molecular analyses conducted on the collected medusae. Our findings show the presence of two distinctive genetic lineages of Craspedacusta in Italy: (i) a group whose distribution ranges from central to northern Italy; and (ii) a group that comprises three populations from northern Italy and the single Sicilian population known to date. Olindiid freshwater jellyfishes of the genus Craspedacusta Lankester, 1880 are native to eastern Asia; however, some species within the genus have been introduced worldwide and are nowadays present in all continents except Antarctica. To date, there is no consensus regarding the taxonomy within the genus Craspedacusta due to the morphological plasticity of the medusa stages. The species Craspedacusta sowerbii Lankester, 1880 was first recorded in Italy in 1946, and until 2017, sightings of the jellyfish Craspedacusta were reported for 40 water bodies. Here, we shed new light on the presence of the freshwater jellyfishes belonging to the genus Craspedacusta across the Italian peninsula, Sardinia, and Sicily. First, we report 21 new observations of this non-native taxon, of which eighteen refer to medusae sightings, two to environmental DNA sequencing, and one to the finding of polyps. Then, we investigate the molecular diversity of collected Craspedacusta specimens, using a Bayesian analysis of sequences of the mitochondrial gene encoding for Cytochrome c Oxidase Subunit I (mtDNA COI). Our molecular analysis shows the presence of two distinctive genetic lineages: (i) a group that comprises sequences obtained from populations ranging from central to northern Italy; (ii) a group that comprises three populations from northern Italy—i.e., those from the Lake Levico, the Lake Santo of Monte Terlago, and the Lake Endine—and the single known Sicilian population. We also report for the first time a mtDNA COI sequence obtained from a Craspedacusta medusa collected in Spain. [ABSTRACT FROM AUTHOR]

The North Sea (NS) is changing rapidly. Temporal variations in fishing intensity and eutrophic conditions, along with the ongoing impact of climate change, act in synergy resulting in modifications in marine communities. Although zooplankton has been extensively investigated, studies often ignore the large-sized meso- and macro-zooplankton (>500 µm), including holoplankton and meroplankton taxa. Here, we examined changes in abundances and community structure of these organisms between 1975 and 2018, using univariate and multivariate analysis, at different taxonomic levels. Abrupt changes in the abundances of (sub)communities occurred during different time periods and resulted in a significant restructuration of the entire community in 2006. These changes were consistent with the regime shifts reported in the NS and were a consequence of the environmental pressures on the whole community or on specific subcommunities. In the long term, the community shifted from higher abundances of hydrozoans and holoplankton taxa to an increasing abundance of decapods. Furthermore, we reveal the environmental variables that most explain the variability in the community dynamics, highlighting the importance of temperature and top-down processes. Our study underlines the relevance of investigations at different taxonomic levels, which elucidates how distinct responses to environmental changes ultimately shape the entire community structure. [ABSTRACT FROM AUTHOR]

Capitate hydrozoans are a morphologically and ecologically diverse hydrozoan suborder, currently including about 200 species. Being grouped in two clades, Corynida and Zancleida, these hydrozoans still show a number of taxonomic uncertainties at the species, genus and family levels. Many Capitata species established symbiotic relationships with other benthic organisms, including bryozoans, other cnidarians, molluscs and poriferans, as well as with planktonic dinoflagellates for mixotrophic relationships and with bacteria for thiotrophic ectosymbioses. Our study aimed at providing an updated and comprehensive phylogeny reconstruction of the suborder, at modelling the evolution of selected morphological and ecological characters, and at testing evolutionary relationships between the symbiotic lifestyle and the other characters, by integrating taxonomic, ecological and evolutionary data. The phylogenetic hypotheses here presented shed light on the evolutionary relationships within Capitata, with most families and genera being recovered as monophyletic. The genus Zanclea and family Zancleidae, however, were divided into four divergent clades, requiring the establishment of the new genus Apatizanclea and the new combinations for species in Zanclea and Halocoryne genera. The ancestral state reconstructions revealed that symbiosis arose multiple times in the evolutionary history of the Capitata, and that homoplasy is a common phenomenon in the group. Correlations were found between the evolution of symbiosis and morphological characters, such as the perisarc. Overall, our results highlighted that the use of genetic data and a complete knowledge of the life cycles are strongly needed to disentangle taxonomic and systematic issues in capitate hydrozoans. Finally, the colonization of tropical habitat appears to have influenced the evolution of a symbiotic lifestyle, playing important roles in the evolution of the group. [ABSTRACT FROM AUTHOR]

The serpulid tube worm Laqueoserpula reussi (Weinzettl, 1910), originally introduced as a gastropod named Burtinella(?) reussi, is described from the Upper Cenomanian and Lower Turonian of the Bohemian Cretaceous Basin. It had usually been confused with other species and genera before 2008. Comparison with specimens from the type locality of the type species of the genus Laqueoserpula Lommerzheim, 1979 confirms the affiliation of the Bohemian species to this genus. The simple prismatic (SP) ultrastructure of the tube wall of L. reussi agrees with an assignment to the tribe Serpulini Rafinesque, 1815. In the Upper Cretaceous, representatives of Laqueoserpula are exclusively found in nearshore deposits, where they are accompanied by a high diverse marine invertebrate fauna. By its compact, large and robust tube forming a spiral and extremely thick tube wall, L. reussi was well-adapted to live in nearshore high energy environments, where its tube could be encrusted by bryozoans, brachiopods and oysters, and infested by hydroids and borers. [ABSTRACT FROM AUTHOR]

The species Monoserius pennarius (Linnaeus, 1758), is particularly abundant in the tropical Indo-West Pacific east of Sri Lanka, yet very limited genetic information exists for this species. Here, we report the assembled-linear mitochondrial genome of M. pennarius collected from the East China Sea. The 15,197 bp mitogenome contains 13 protein-coding genes (PCGs), two tRNA genes, and two rRNA genes. Notably, the gene order in this mitogenome differs from that of other hydrozoans within the same taxonomic order. Phylogenetic analysis, based on 13 concatenated mitochondrial PCGs, recovered M. pennarius as a sister of Nemalecium lighti (Hargitt, 1924), outside the other Leptothecata hydrozoans, suggesting paraphyly of Leptothecata. The mitogenome of M. pennarius, serving as the first publicly available for the family Aglaopheniidae, holds foreseeable value for investigating Leptothecata evolution. [ABSTRACT FROM AUTHOR]

Cnidarians—the phylum including sea anemones, corals, jellyfish, and hydroids—are one of the oldest groups of predatory animals. Nearly all cnidarians are carnivores that use stinging cells called cnidocytes to ensnare and/or envenom their prey. However, there is considerable diversity in cnidocyte form and function. Tracing the evolutionary history of cnidocytes may therefore provide a proxy for early animal feeding strategies. In this study, we generated a time‐calibrated molecular clock of cnidarians and performed ancestral state reconstruction on 12 cnidocyte types to test the hypothesis that the original cnidocyte was involved in prey capture. We conclude that the first cnidarians had only the simplest and least specialized cnidocyte type (the isorhiza) which was just as likely to be used for adhesion and/or defense as the capture of prey. A rapid diversification of specialized cnidocytes occurred through the Ediacaran (~654–574 million years ago), with major subgroups developing unique sets of cnidocytes to match their distinct feeding styles. These results are robust to changes in the molecular clock model, and are consistent with growing evidence for an Ediacaran diversification of animals. Our work also provides insight into the evolution of this complex cell type, suggesting that convergence of forms is rare, with the mastigophore being an interesting counterexample. Highlights: Cnidarian stinging cells diversified through the Ediacaran, demonstrating that animal predation evolved before the Cambrian explosion. The mastigophore is rare case of a complex cell type evolving more than once. [ABSTRACT FROM AUTHOR]

Siphonophores (Cnidaria: Hydrozoa) are abundant predators found throughout the ocean and are important constituents of the global zooplankton community. They range in length from a few centimeters to tens of meters. They are gelatinous, fragile, and difficult to collect, so many aspects of the biology of these roughly 200 species remain poorly understood. To survey siphonophore genome diversity, we performed Illumina sequencing of 32 species sampled broadly across the phylogeny. Sequencing depth was sufficient to estimate nuclear genome size from k -mer spectra in six specimens, ranging from 0.7 to 2.3 Gb, with heterozygosity estimates between 0.69% and 2.32%. Incremental k -mer counting indicates k -mer peaks can be absent with nearly 20× read coverage, suggesting minimum genome sizes range from 1.4 to 5.6 Gb in the 25 samples without peaks in the k -mer spectra. This work confirms most siphonophore nuclear genomes are large relative to the genomes of other cnidarians, but also identifies several with reduced size that are tractable targets for future siphonophore nuclear genome assembly projects. We also assembled complete mitochondrial genomes for 33 specimens from these new data, indicating a conserved gene order shared among nonsiphonophore hydrozoans, Cystonectae, and some Physonectae, revealing the ancestral mitochondrial gene order of siphonophores. Our results also suggest extensive rearrangement of mitochondrial genomes within other Physonectae and in Calycophorae. Though siphonophores comprise a small fraction of cnidarian species, this survey greatly expands our understanding of cnidarian genome diversity. This study further illustrates both the importance of deep phylogenetic sampling and the utility of k -mer–based genome skimming in understanding the genomic diversity of a clade. [ABSTRACT FROM AUTHOR]

The association between two hydrozoans, Stylaster sp. and Millepora spp., has been described as a case of pseudo-auto-epizoism, and has only been reported from the Caribbean region of the Atlantic Ocean. Here, we report on the occurrence of this association in the Pacific Ocean on coral reefs around Iriomote-jima Island, Japan, suggesting the association to be more widespread than had previously been thought. Moreover, Stylaster sp. colonies were observed living healthily on bleached and dead branches of Millepora spp., indicating that this interaction is facultative. The interaction reported here differs from the relationship between the Caribbean Stylaster roseus and Millepora alcicornis by the connection points between the two partners, which is made evident by the whitening of the Millepora counterpart in Iriomote-jima Island, while being seamless in the Caribbean association. Further research is necessary to fully understand the nature of these relationships, comprehending under what conditions it occurs, and establishing which species are involved in the interactions. [ABSTRACT FROM AUTHOR]

The invasion of non-native species has been a chronic problem in reservoirs of hydroelectric plants. Among the species recorded in Brazil, the cnidarian Cordylophora caspia is often misidentified as macrophytes or completely overlooked, although reports state that the colonies obstruct structures and pipes in industrial plants, generating high maintenance costs. In addition to modifying the ecological balance of invaded ecosystems, studies indicated that C. caspia can influence the occurrence of other invasive species, such as Limnoperna fortunei. In this study, we reported two new records for C. caspia in Brazil, the first occurrence in Minas Gerais and Goiás. We described the colonies in detail and reviewed the known geographic distribution of the species in Brazilian waters. We provided the first Brazilian genetic sequences of the species, which were phylogenetically placed into a broad evolutionary inference using C. caspia COI sequences available from different regions of the world. Our results indicate that there is no clear pattern of ecophysiological specialization of main clades regarding salinity that would justify the validation of the nominal C. lacustris for freshwater specimens. High levels of genetic differentiation in the lineages support the existence of multiple cryptic species within the genus Cordylophora. Finally, our ancestral state reconstruction analysis suggested a presumed freshwater origin for C. caspia and independent shifts between fresh and brackish waters. Advances in the study of populations from different regions of the world will be important for further understanding species delimitation, possible routes of invasion, economic impacts, and ecological interactions, including with other invasive species. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the substrate preferences of hydroid polyps sampled in eight different stations on the coastline of Antalya Bay. Sampling was performed by freedive to identify the hydroid polyp fauna and certain physicochemical (salinity, temperature, dissolved oxygen, electrical conductivity, chl-a) and biological characteristics were determined. A total of 35 hydroid species were identified as epiphytic, epilithic and epizoic in the region. The most commonly preferred substrates by the species were; rocks (20 species), Ellisolandia elongata (J.Ellis & Solander) K.R.Hind & G. W. Saunders, 2013 (18 species), Balanus sp. Costa, 1778 (9 species), macroalgae Posidonia oceanica (Linnaeus) Delile, 1813, and leaves (8 species). Among all species, one species prefers just epilithic substrates, four species prefer only epizoic substrates, and seven species prefer only epiphytic substrates. Acauloides ammisatum, Eudendrium sp., Turritopsis. nutricula, Pennaria. disticha, Clytia noliformis, Halecium tenellum, Halopteris diaphana, Dynamena disticha and Salacia desmoides are found in all substrate types (EP,EZ,EL). [ABSTRACT FROM AUTHOR]

AbstractEirene ceylonensis, a hydrozoan jellyfish species with a complex polymorphic life cycle, is widely distributed in the Chinese coastal sea. In this study, we conducted sequencing and analysis of the first complete mitochondrial genome of E. ceylonensis, obtained from the coastal sea of Qinhuangdao, China. The linear mitochondrial genome is 14,997 bp in length with the overall AT content being 72.8%, encoding 13 protein-coding genes (PCGs), two transfer RNA (tRNA) genes (tRNA-Met and tRNA-Trp) and two ribosomal RNA (rRNA) genes (rrnS and rrnL). Phylogenetic analysis of 13 PCGs suggests that the E. ceylonensis is closely related to Laomedea flexuosa. The availability of the complete mitochondrial genome of E. ceylonensis will be useful for studying the evolutionary relationships of hydrozoan jellyfish species.

Rhodaliids, a specific family of siphonophores inhabiting the benthic zone, have remained enigmatic due to their rarity and elusive nature. These unique organisms, primarily found in open ocean habitats, exhibit distinctive features and are characterized by complex structures. During the Red Sea Decade Expedition, two rhodaliid specimens were collected at the sea bed at water depths of 438 and 495 meters. Regardless of challenges in specimen preservation, detailed morphological analysis revealed unique characteristics. Genetic analysis, employing the 16S rRNA marker, revealed one specimen closely related to Thermopalia taraxaca, while the taxonomic traits of this specimen suggested the identification of Archangelopsis jagoa. While most of the morphological features of the second specimen were also very similar to A. jagoa, some differences in coloration suggest the discovery of either an unusual colour variant or a potential new species within this genus. Notably, this study reports the first sequencing of A. jagoa. This species demonstrated a capacity to thrive in low-oxygen environments, challenging conventional assumptions about their habitat requirements. Despite difficulties in specimen handling and genetic analysis limitations due to a lack of comprehensive data, this research sheds light on the elusive world of benthic rhodaliids. [ABSTRACT FROM AUTHOR]

Introduction: Host-parasite associations provide very useful models to study adaptive processes. We investigated the interaction between carnivorous marine gastropods, the Ovulidae or egg-cowries, and their cnidarian food targets. Ovulidae (Fleming, 1828), is a family of specialized carnivorous caenogastropods that feed by browsing on octocorals (Anthozoa: Octocorallia: Malacalcyonacea and Scleralcyonacea) or, to a much lesser degree, on antipatharians (Anthozoa: Hexacorallia: Antipatharia) and Stylasteridae (Hydrozoa: Hydroidolina: Anthoathecata). Very scanty information is available on the phylogenetic relationships and the degree of specificity of the relationship with the cnidarians of this corallivorous lineage, especially for deepwater taxa. Methods: To assess taxonomic identifications and investigate cnidarian/ovulid relationships in the context of their evolution, we generated an extensive molecular dataset comprising two mitochondrial (cox1 and 16S rDNA) and one nuclear gene (28S rDNA) from 524 specimens collected worldwide. The coral hosts of the ovulid species have been identified by integrating literature data with new records, employing morphological and/or molecular (the mitochondrial 16S rDNA and mtMSH, and the nuclear ITS2) markers. Results: We obtained a molecular phylogenetic framework for the Ovulidae, time-calibrated with nine reliable fossil records. An ancestral state reconstruction allowed to identify Hexacorallia or Hydroidolina as the most likely ancestral cnidarian host for the Ovulidae. Discussion: Our phylogenetic hypothesis revealed the existence of groups that do not completely correspond to the currently employed subfamilial arrangement. Concerning trophic ecology, while only pediculariines (Pedicularia and allied) are associated with hydrozoans (Stylasteridae), our results suggest that some ovulid lineages shifted independently between octocorals and hexacorals. [ABSTRACT FROM AUTHOR]

Scyphozoan medusae are critical components of marine ecosystems; however, our knowledge on their population dynamics and life history needed to understand their role on ecosystem functioning is relatively scarce. We used data from fish-stock assessment cruises (1993–2013), artisanal fisheries and stranding events (2006–2007), to assess spatio-temporal variation in biomass, growth and reproduction, of a large and abundant scyphomedusae (Lychnorhiza lucerna) in a productive estuarine ecosystem (Río de la Plata Estuary, RLPE) (35°S-57°W) from the Southwestern Atlantic Ocean. Medusae consisted of sexually mature individuals only, occurring consistently during austral summer. Medusae biomass displayed a patchy distribution, concentrating mainly in two geographically different hot-spots associated to a frontal feature (turbidity front) of the RLPE. Individual size, relative fecundity, and degree of gonad development varied significantly between hot-spots. Biomass varied greatly among years. Bell diameter, wet weight, and percentage of fully developed oocytes increased during the first half of the summer but decreased during the second half of it. Our results suggest high predictability of the period of occurrence and the distribution of L. lucerna in the RLPE. Physical mechanisms of medusa aggregation, potential effects of medusae on zooplankton dynamics, fisheries production, and conservation of sea turtles, as well as their potential for the development of a local jellyfish fishery, are here discussed. This work provides novel information on patterns of distribution, growth and development of L. lucerna medusae, which can help to enhance our understanding of the role of large medusae on ecosystem functioning of marine ecosystems worldwide. [ABSTRACT FROM AUTHOR]

Lipid molecular species profiles of marine invertebrates still remain very poorly understood. We have studied year-round variations in the levels of chlorophylls and reserve lipid molecular species such as triacylglycerols (TG), and monoalkyldiacylglycerol (MADAG) in octocoral Sinularia flexibilis and the hydrocoral Millepora platyphylla. Our results show that M. platyphylla and S. flexibilis display differences in the pattern of year-round variations in reserve lipids. Only in M. platyphylla, total reserve lipids correlated with seawater temperature, which may be associated with hydrocoral's predation on plankton. A decrease in total lipids leads to an increase in chlorophyll levels, which indicates transition to autotrophic nutrition mode. Differences between corals also may be associated with species of hosted symbiotic dinoflagellates that can be a source of fatty acids (FAs) for the biosynthesis of TG and MADAG by the coral host. This may be an explanation for the annual variations in TG molecular species with 22:6 PUFA in M. platyphylla, and TG molecular species with saturated, mono-, and dienoic FAs in S. flexibilis. Based on S. flexibilis as an example, we have shown that MADAGs are suggested to have several molecular pools, of which one may be related to the molecular profile of structural phospholipids with the same FAs. Year-round studies of lipidome can help understand the range and possible causes of seasonal biochemical variations in corals and may be useful for future analysis of trophic and symbiont–host interactions in cnidarians. [ABSTRACT FROM AUTHOR]

Subsurface reflectors in radar sounder data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express spacecraft indicate significant dielectric contrasts between layers in the Martian Medusae Fossae Formation (MFF). Large density changes that create dielectric contrasts are less likely in deposits of volcanic ash, eolian sediments, and dust, and compaction models show that homogeneous fine‐grained material cannot readily account for the inferred density and dielectric constant where the deposits are more than a kilometer thick. The presence of subsurface reflectors is consistent with a multi‐layer structure of an ice‐poor cap above an ice‐rich unit analogous to the Martian Polar Layered Deposits. The volume of an ice‐rich component across the entire MFF below a 300–600 m dry cover corresponds to a global equivalent layer of water of ∼1.5 to ∼2.7 m or ∼30%–50% of the total estimated in the North Polar cap. Plain Language Summary: The Medusae Fossae Formation (MFF), located near the equator of Mars along the dichotomy boundary between the lowlands of the northern hemisphere and the cratered highlands of the southern hemisphere, is one of the largest and least understood deposits on Mars. The Mars Advanced Radar for Subsurface and Ionospheric Sounding radar sounder detects echoes in MFF deposits that occur between the surface and the base which are interpreted as layers within the deposit like those found in Polar Layered Deposits of the North and South Poles. The subsurface reflectors suggest transitions between mixtures of ice‐rich and ice‐poor dust analogous to the multi‐layered, ice‐rich polar deposits. An ice‐rich part of the MFF deposit corresponds to the largest volume of water outside the polar caps, or a global equivalent layer of water of ∼1.5 to ∼2.7 m. Key Points: Mars Advanced Radar for Subsurface and Ionospheric Sounding radar sounder data reveals layering in the Medusae Fossae Formation (MFF) depositsLayers are likely due to transitions between mixtures of ice‐rich and ice‐poor dust, analogous to those in Polar Layered DepositsAn ice‐rich portion of the MFF deposit may contain the largest volume of water in the equatorial region of Mars [ABSTRACT FROM AUTHOR]

From samples for the phytoplankton collected from the sea surface water of 67 stations along the entire Turkish Mediterranean coast during June-July 2019, three juvenile gelatinous organisms were recorded. Two cnidarian-hydrozoan species (Podocorynoides minima and Gastroblasta raffaelei) and one ctenophore (Bolinopsis cf. vitrea) occurred near Mersin Bay. The specimens were determined at the juvenile or eumedusoid stages. Referring to the literature, Gastroblasta raffaelei was presumably about 4-5-day old (1.05 x 1.56 mm in elliptical diameter), and Podocorynoides minima about a stage of liberated eumedusoid (0.327 x 0.316 mm in bell diameter x height). The specimen of Bolinopsis cf. vitrea was measured to be 11 mm in lobate (total) length and 8.6 mm in body width. Interestingly, all species were found at different locations close to each other on the set of the water rim current speeding easterly up to about 0.5 m s-1. Gastroblasta raffaelei and Podocorynoides minima were first recorded on the Turkish Mediterranean coast. Early-staged specimens of these three species were described and discussed for their diagnostic structures with their occurrence in the Turkish Mediterranean Sea after the hydrozoans were reported in the Sea of Marmara, the ctenophore in the Black Sea, and other seas of the Mediterranean basin. The present study also discussed possible and presumable pathways of recent increased Turkish Mediterranean records of specimens that have been observed in the West Mediterranean Sea and the Adriatic Sea. [ABSTRACT FROM AUTHOR]

The marine hydroids (Cnidaria: Hydrozoa) of south-eastern Australia are reviewed and commonly-encountered species are described and illustrated. A brief introduction to hydroid morphology, ecology and study methods is also provided, along with an account of early investigations into hydroids and a brief history of Australian hydroid studies. [ABSTRACT FROM AUTHOR]

Sarsia tubulosa (M. Sars, 1835), a colonial hydrozoan of the family Corynidae, is common in the Barents Sea. This study provides new evidence that the species acts as an epibiont of the red king crab Paralithodes camtschaticus, a non-indigenous but remarkably abundant decapod crustacean of immense commercial value in the coastal regions of the sea. This finding adds to the current collection of identified epibionts on the red king crab and highlights the prospect of ongoing symbiotic relationships between the crab and the regional fauna. We also provide photographic evidence of S. tubulosa colonies and a comparative morphological evaluation with another closely related corynid, Coryne hincksi Bonnevie, 1898, previously found on the red king crab. The main differences between these two species are the location of the gonophores (reproductive organs) on the hydranths and the final stage of their development: in the form of free-floating medusae (S. tubulosa) or remaining sessile as sporosacs (C. hincksi). Other distinguishing features include variations in hydranth morphology, number and arrangement of tentacles, and structural development of gonophores. [ABSTRACT FROM AUTHOR]

Both wild and reared bivalves can host hydroids from the Eirenidae family which settle on the soft body parts of their host. Thousands of hydroids have been observed on a single bivalve, and often have severe detrimental effects on the host. However, this relationship has received little attention in aquaculture research, which is probably due to a lack of baseline data. An extensive review was conducted (i) to show the current level of knowledge on the association between eirenids and bivalves, providing a benchmark for future research; (ii) to detect a critical combination of biotic/abiotic factors that could switch the relationship from commensalism to infestation and (iii) to identify research priorities for future studies. Seventy scientific papers were screened to provide ecological information useful in understanding the hydroid‐host‐environment interactions and to show the global spatial and bathymetric distribution of the relationship. Although the main parameters influencing the hydroid abundance were identified, it was challenging to collate information from such heterogeneous data sources. A standardized method for data collection is proposed to obtain more robust and comparable data on the association. The most relevant and unstudied issue is the potential physiological and qualitative changes that could occur in infested bivalves. Monitoring the association could provide data needed to prevent or to control hyper‐proliferation of the symbionts and to detect eventual synergistic effects with climate change. This could be fundamental for species living in areas particularly prone to climate regime shifts, such as semi‐enclosed basins and estuarine habitats. [ABSTRACT FROM AUTHOR]

Introduction: Periodic organ arrangements occur during growth and development and are widespread in animals and plants. In bilaterian animals, repetitive organs can be interpreted as being periodically arranged along the twodimensional space and defined by two body axes; on the other hand, in radially symmetrical animals and plants, organs are arranged in the three-dimensional space around the body axis and around plant stems, respectively. The principles of periodic organ arrangement have primarily been investigated in bilaterians; however, studies on this phenomenon in radially symmetrical animals are scarce. Methods: In the present study, we combined live imaging, quantitative analysis, and mathematical modeling to elucidate periodic organ arrangement in a radially symmetrical animal, Coryne uchidai (Cnidaria, Hydrozoa). Results: The polyps of C. uchidai simultaneously formed multiple tentacles to establish a regularly angled, ring-like arrangement with radial symmetry. Multiple rings periodically appeared throughout the body and mostly maintained symmetry. Furthermore, we observed polymorphisms in symmetry type, including tri-, tetra-, and pentaradial symmetries, as individual variations. Notably, the types of radial symmetry were positively correlated with polyp diameter, with a larger diameter in pentaradial polyps than in tetra- and triradial ones. Our mathematical model suggested the selection of sizecorrelated radial symmetry based on the activation-inhibition and positional information from the mouth of tentacle initiation. Discussion: Our established quantification methods and mathematical model for tentacle arrangements are applicable to other radially symmetrical animals, and will reveal the widespread association between size-correlated symmetry and periodic arrangement principles. [ABSTRACT FROM AUTHOR]

This document provides a diagnostic protocol for Melampsora medusae, a rust fungus that affects poplar trees. It discusses the symptoms, detection, and identification of M. medusae, including morphological and molecular methods. The document specifically focuses on the molecular tests for the detection of M. medusae f. sp. deltoidae, a rust pathogen found on poplar trees. It provides detailed instructions for conducting real-time PCR, including nucleic acid extraction, PCR conditions, controls, and interpretation of results. The document also includes information on performance characteristics and contact information for further inquiries. This protocol can be useful for researchers studying this plant pathogen and conducting diagnostic tests. [Extracted from the article]

The temperature of the water surface layer in the Arctic may increase significantly in the coming decades. To what extent will shallow-water fauna be affected by warming? We investigated this issue using an example of one species of colonial hydroid, Dynamena pumila. We judged its reaction to warming via its pulsation activity and the growth of stolons. Pulsations of the coenosarc in colonial hydroids are a sensitive indicator of the body's reaction to the influence of environmental factors. We tested the ability of D. pumila colonies to survive and adapt to existing at 25 °C for five days. After raising the temperature from 14 °C to 25 °C, colony growth and the pulsation of stolon growth tips on the first day increased and then decreased during the day. In the following days, the growth pulsations almost ceased, the colonies stopped growing, and their coenosarcs began to exfoliate from their perisarcs. However, by the fourth day, this process slowed down, and the colonies existed in an economy mode of experiencing unfavourable conditions. The thermal shock continued in the experiment for five days. Then, after the temperature dropped from 25 °C to 15–16 °C, all the colonies recovered within five days and continued to grow. [ABSTRACT FROM AUTHOR]

The phosphorus content in the dry matter of modern-day Cnidarians (Hydrozoa, Scyphozoa and Anthozoa) collected in the different parts of the world's oceans ranges from 0.14 to 1.3% wt. Nektonic Cnidarians can form major aggregations in marine basins and should therefore be regarded as an important component of phosphorus flux into sediment. Seventy-five per cent of the Ediacaran fossils were interpreted as the moulds of soft-bodied organisms resembling modern-day Cnidaria. Therefore, ancient Cnidarians in the Ediacaran epeiric basins could be a source of phosphorus during the deposition of the earliest sedimentary phosphorites. [ABSTRACT FROM AUTHOR]

Planktonic lifestyle of polyps in representatives of Margelopsidae are very different from all other species in the hydrozoan clade Aplanulata. Their evolutionary origin and phylogenetic position have been the subject of significant speculation. A recent molecular study based only on COI data placed Margelopsidae as a sister group to all Aplanulata, an unexpected result because margelopsid morphology suggests affiliation with Tubulariidae or Corymorphidae. Here we used multigene analyses, including nuclear (18S rRNA and 28S rRNA) and mitochondrial (16S rRNA and COI) markers of the hydroid stage of the margelopsid species Margelopsis haeckelii and the medusa stage of Margelopsis hartlaubii to resolve their phylogenetic position with respect to other hydrozoans. Our data provide strong evidence that M. haeckelii, the type species of Margelopsis, is a member of the family Corymorphidae. In contrast, M. hartlaubii is sister to Plotocnide borealis, a member of Boreohydridae. These results call into question the validity of the genus Margelopsis and the family Margelopsidae. The systematic position of M. haeckelii is discussed in light of the phylogeny of Corymorphidae. [ABSTRACT FROM AUTHOR]

Eirene ceylonensis, a hydrozoan jellyfish species with a complex polymorphic life cycle, is widely distributed in the Chinese coastal sea. In this study, we conducted sequencing and analysis of the first complete mitochondrial genome of E. ceylonensis, obtained from the coastal sea of Qinhuangdao, China. The linear mitochondrial genome is 14,997 bp in length with the overall AT content being 72.8%, encoding 13 protein-coding genes (PCGs), two transfer RNA (tRNA) genes (tRNA-Met and tRNA-Trp) and two ribosomal RNA (rRNA) genes (rrnS and rrnL). Phylogenetic analysis of 13 PCGs suggests that the E. ceylonensis is closely related to Laomedea flexuosa. The availability of the complete mitochondrial genome of E. ceylonensis will be useful for studying the evolutionary relationships of hydrozoan jellyfish species. [ABSTRACT FROM AUTHOR]

New individuals of Porpita porpita were detected along the Italian coasts of the Mediterranean Sea. In recent years, due to warming Mediterranean waters, the species has spread even further. This observation opens new horizons for further reports of this species in the Ionian and Tyrrhenian Seas of Italy.

The temperature of the water surface layer in the Arctic may increase significantly in the coming decades. To what extent will shallow-water fauna be affected by warming? We investigated this issue using an example of one species of colonial hydroid, Dynamena pumila. We judged its reaction to warming via its pulsation activity and the growth of stolons. Pulsations of the coenosarc in colonial hydroids are a sensitive indicator of the body’s reaction to the influence of environmental factors. We tested the ability of D. pumila colonies to survive and adapt to existing at 25 °C for five days. After raising the temperature from 14 °C to 25 °C, colony growth and the pulsation of stolon growth tips on the first day increased and then decreased during the day. In the following days, the growth pulsations almost ceased, the colonies stopped growing, and their coenosarcs began to exfoliate from their perisarcs. However, by the fourth day, this process slowed down, and the colonies existed in an economy mode of experiencing unfavourable conditions. The thermal shock continued in the experiment for five days. Then, after the temperature dropped from 25 °C to 15–16 °C, all the colonies recovered within five days and continued to grow.

Acanthophora spicifera, a red alga considered an alien species, was discovered for the first time on the Pacific coast of Mexico in 2006 from a locality inside La Paz Bay, Gulf of California. Since then, more records have shown its presence, 17 localities having been added up to 2015. A two-year field study (2020-2022) visiting 31 sites along the coast of La Paz Bay, complemented with data from literature and citizen science, resulted in a database of 709 entries that spans the data from 2004 to 2023. These data showed a distribution that goes from Punta Coyote, close to Boca Grande, the northern entrance to the Bay to Playa Tecolote in the south, more than 100 km of coastline, including Espiritu Santo Archipelago, an area considered a natural reserve since 2007. Anthropogenic activity and environmental variables did not present statistical differences that explain A. spicifera spreading. It represents a naturalised alien species without evidence of a negative impact. Still, it soon could acquire the status of invasive species together with its epibionts Bryozoa and Hydrozoa detected in this study.