Morphological symmetry abnormalities in cheliped appendages of alpheid shrimps are extremely rare and poorly recorded in the literature. A symmetric minor cheliped were, for example, observed in queen females belonging to Synalpheus eusocial species. Symmetric major chelipeds were now described in Synalpheus fritzmuelleri individuals living in shallow Brazilian waters. These individuals were found in symbiotic association with the bryozoan Schizoporella sp. (biogenic substrate) adhering to the pilings of Ubatuba Bay docks, São Paulo State. Only one of 20 sampled S. fritzmuelleri individuals presented anomalous symmetric chelipeds. Based on carapace length, size, and morphological features, the analyzed specimens seemed to be juvenile; thus, the hypothesis of anomalous condition can be directly linked to genetic inhibition of the mechanism accounting for major cheliped development in this ontogeny phase. Studies like the present one often provide remarkable information on animal morphology and can be used as reference in evolutionary assessments to be conducted in the future.

Luidia iwakiensis n. sp. (Asteroidea, Echinodermata) is described in Japanese waters. A molecular phylogenetic analysis including 18 Luidia species supported Döderlein L (1920, Siboga Expedition 4, 193–291) four morphogroups. Morphological reconsideration revealed three of the eight criteria of the morphogroup adopted by Döderlein were justified, but the remaining five characters were rejected. The placement of the new species in the Ciliaris-group was supported by molecular as well as morphological evidence, however, it varies from other species of Ciliaris-group by arm number, length of major inferomarginal spines, and pedicellariae on actinal plates.

A eulimid gastropod of the genus Ophieulima, parasitic on the disc of the ophiactid brittle star Ophiactis dyscrita, was collected from 256–343 m deep off Kanagawa, central Japan. This represents the first record of the genus from Japanese waters and even from the North Pacific Ocean. Here we describe it as Ophieulima yoshiharai n. sp. The generic assignment is justified by its conchological characters including (1) a small, conical shape with convex teleoconch whorls, (2) many fine growth lines and some strong growth pause scars on the teleoconch, (3) a well-developed, twisted columella, and (4) a multispiral, brownish transparent protoconch. Ophieulima yoshiharai n. sp. is distinguishable from the three (two named and one undescribed) extant, as well as two fossil congeners by its slender shell with the length of 2.1 times larger than width, a small aperture and a protoconch of 3.5 whorls. The new species is also characterized by its bathymetric distribution, which is shallower than the extant species of Ophieulima. On the other hand, the hosts of Ophieulima species are so far restricted to ophiuroids of the genus Ophiactis and the three named species have mostly been found attached to the lateral and/or dorsal sides of the host's disc, suggesting their similar parasitic ecology.

The frequency of growth increments in the tube wall of the Mesozoic and Cenozoic serpulids is in the range of modern species (i.e. 7–37 growth lines per 50 μm). The growth increments of serpulids do not show correlation with the water temperature and presumably cold water and warm water serpulid species are growing on average with similar speed in terms of number of growth lines per 50 μm. The large serpulid species have usually significantly larger growth increments than smaller species and presumably also grew faster than smaller species. The species with denser skeletons have lower growth rates than species with more porous skeletons. It is possible that serpulids do not have to calcify faster to produce thicker growth increments with lower density.

Two species of deep-sea skates, Amblyraja frerichsi and Notoraja martinezi, are reported for the first time in Peruvian waters, representing the first record of their respective genera from the country. Earlier, A. frerichsi was known from both the southwestern Atlantic (off Brazil, Uruguay, and Argentina) and southeastern Pacific (off Chile), while N. martinezi was known from Costa Rica to Ecuador in the eastern-central and southeastern Pacific. This study contributes to the limited knowledge of deep-sea fish diversity along the South American west coast, and stresses the need of further taxonomic research in the region, particularly in light of the ecological importance of this group of fishes in marine ecosystems and its conservation state worldwide.

Amphilochidae comprises 92 species of small and colourful amphipods that live associated with sessile marine organisms. Hourstonius is one of the most diverse genera with 17 described species, most of the species are recorded from North Temperate Pacific and Tropical Atlantic and live in shallow waters. Only three species of Amphilochidae are recorded in Brazil, and from the genus Hourstonius, there is a single species, H. wakabarae. In the present work, we describe a new species of Hourstonius from Todos-os-Santos Bay, the second species of the genus to the country and the first record of this genus from Bahia State. A taxonomic key and an overview of the genus across the globe are also provided.

Nine hundred and ninety-two (992) specimens of Pseudocyclops lerneri Fosshagen, 1968 (Copepoda: Pseudocyclopidae) were collected from the largest South Atlantic coral reef, Abrolhos bank (17°20′–18°10′S; 38°35′–39°20′W). Specimens were distinguished from other Pseudocyclops spp. by a close examination of the female and male fifth leg. This is the first record of the family Pseudocyclopidae in the South Atlantic. We further indicate that the low number of studies on this species, and as a consequence, the poorly understood ecology of Pseudocyclopidae may be caused by the use of inadequate sampling methods, indicating the use of demersal-focused samplers, such as emergence traps as an alternative to the sampling of these bottom-dwelling copepods.

Kelp forests are being degraded and/or lost in many regions, and as such, interest in active kelp restoration approaches to reinstate forests is growing. ‘Green gravel’ is a promising new kelp restoration technique that involves seeding small rocks with kelp zoospores, rearing the gametophyte and juvenile sporophyte stages in aquaria before outplanting them at restoration sites. However, to be considered a viable approach to kelp forest restoration, the efficacy of this technique needs to be assessed across a range of environmental contexts and kelp species. Here, we aimed to understand the utility of green gravel as a kelp restoration technique for wave-exposed intertidal shores. Two substrate types – gravel and cobbles – were seeded with Saccharina latissima, reared in the aquarium and outplanted at two sites along the northeast coast of England. Outplanted rocks were monitored for retention, and the density and length of S. latissima. Juvenile sporophytes persisted on both rock types, although declines in density and variations in length were observed over time. Substrate retention was low, with gravel more likely to be removed from restoration sites compared to cobbles, and all outplanted rocks were lost after eight months. While our initial testing of the green gravel restoration technique on wave-exposed shores was not successful, our results provide important insights for developing/refining the technique and a baseline for comparison for future efforts. However, prior to commencing large-scale kelp restoration in wave-exposed areas using green gravel, further testing of the technique and comparisons with other restoration approaches are needed.

Grey seals from both the Atlantic and Baltic Sea subspecies are recovering from dramatic declines and recolonising former ranges, potentially leading to overlapping distributions and an emerging subspecies transition zone in Kattegat between Denmark and Sweden. The two subspecies have asynchronous moulting and pupping seasons. We present aerial survey data from 2011 to 2023 in Danish Kattegat during the Atlantic subspecies' moulting (March–April) and pupping (December–January) seasons, as well as the Baltic subspecies' moulting season (May–June). During the Atlantic subspecies' peak moulting season, 82% of the grey seals were recorded north of the island of Læsø (N57°18′, E11°00′). In contrast, during the Baltic moulting season in those years, only 9% of the grey seals were recorded here. This indicates a predominance of Atlantic grey seals in the north and Baltic grey seals in central and southern Kattegat. In 2022 and 2023, three pups were recorded around Læsø during early January, which coincides with the pupping season of northern Wadden Sea grey seals. Previously, pups have been recorded in the same locations during the Baltic pupping season, which demonstrates overlapping breeding ranges. Grey seals are known to have plasticity in the timing of pupping indicated by a west to east cline of progressively later pupping in the eastern North Atlantic. Historical sources document that the Baltic pupping season in Kattegat was earlier than it has been in recent years. Thus, the expanding ranges may be associated with convergence of Atlantic and Baltic subspecies' pupping seasons and potential hybridisation in this emerging transition zone.

Two separate sightings, two years apart, of the mimic octopus Thaumoctopus mimicus Norman & Hochberg, 2005 are reported from the Inhambane Province of southern Mozambique within the protected waters of the Vilanculos Coastal Wildlife Sanctuary. Individuals were encountered in May 2020 and 2022 in shallow waters, at a depth of less than 30 cm. Both individuals were fully exposed moving along a sandy substrate at the water's edge in a tidal flat. These represent the first documented sightings of T. mimicus in Mozambique, confirming the occurrence of the species along the eastern coast of Africa and extending this species' known range west from the Arabian Sea and south from the Red Sea.

Intertidal macrobenthos at the small Chernaya Bight (the White Sea) was surveyed six times during 1993–2018 in order to study spatiotemporal variability. Distributions of sediments and macrophytes were highly variable in both space and time, as were most macrofaunal community attributes. Biomass slightly increased with time, while no long-term trends were found in total abundance, diversity, or functional structure. All community attributes were patchily distributed across the beach, and their patterns were not spatially autocorrelated and poorly associated with sediment properties, but changed considerably from year to year. Temporal changes in the community composition were considerable but less substantial compared with the spatial variations. The overall dynamics of species structure did not show any regular trend-like pattern but formed quasicyclic trajectories in ordination space, with nondirectional, spatially noncorrelated fluctuations around some relatively stable state. Comparison with two other neighbouring intertidal sites, studied annually in 1987–2017, showed that macrofauna at every site had similar average biomasses and common dominant species; however, the communities maintained their specificity in structure and exhibited distinct types of dynamics. In particular, the communities demonstrated different long-term trends in total biomass and diversity and followed their own paths in dynamics, appearing as differently oriented interannual trajectories. Nine most abundant species revealed no significant among-site correlations in abundance, and only two bivalve species showed good intersite agreement in dynamics of biomass. We suggest that local benthic communities are largely influenced by site-specific environmental conditions, resulting in independent and even opposite patterns of dynamics in neighbouring localities.

Otolith morphological and microchemical analyses are relatively new scientific research methods used in fish stock evaluation and management. However, in Tunisia, only morphological methods have been used. The objective of this study was the Sarpa salpa stock discrimination of Djerba and Kerkennah by the otoliths morphological and microchemical analysis, while carrying out a fluctuating asymmetry analysis and a stock comparison of males and females for each population. The results revealed significant differences between the Djerba and Kerkennah populations, significant differences between the stocks of males and females in each population, and a highly significant fluctuating asymmetry for both populations. The results of the otolith morphological analysis were similar to those of the microchemical analysis. This result proves that both morphological and microchemical analyses are powerful tools for fish stock discrimination.

Both present-day and fossil molluscan assemblages offer an opportunity for a better understanding of the structure and organization of both modern and past benthic communities. In this framework, drill holes are used widely to explore predator–prey interactions. This research focuses on predation marks, especially drill holes, recorded on modern molluscan assemblages in a Patagonian sector of the Argentinean continental shelf. Shelled molluscs (n = 2179) were recovered from 27 to 135 m depths covering a long latitudinal extent (between 39° and 54°S). For each station, taxonomic position, ecological composition and relative abundance of taxa were determined, and then drilling frequency (DF) was calculated to infer drilling intensity. The collected molluscs belong to 37 families, with Veneridae being the most abundant in terms of the number of specimens (n = 419). Specimens with drill holes (n = 226) belong to 21 families (with at least 33 different species). Most of them are suspension feeders (85.8%) and the remaining percentage comprised other trophic types. Naticids and muricids, as main potential predators, together account for 19.6% of the gastropods present in the molluscan assemblages. DF across all the stations was moderate (9.9%) but varied between low (0–2.4%) and high (28.9%). These results do not show a trend linked to latitude or depth, and the great variability of DF between stations suggests that other local ecological or environmental conditions would influence drilling predation at a small spatio-scale.

The present research documents new distributional records of two gobioid fishes, Acentrogobius vanderloosi Allen, 2015 and Pseudogobius fulvicaudus Huang, Shao, and Chen, 2014 from the southeastern coast of India. Indian coastal waters provide suitable habitats for many gobioid fishes due to its varied ecosystems. The confusion over the identity of a number of gobioid fishes in India suggests the need for more studies on these fishes to better understand their diversity, taxonomy, and geographical distribution. The present record of these species from the southeastern coast of India expands the known distribution of these species.

Length–weight relationships (LWR) were determined for Deania calceus, Deania profundorum, Merluccius polli, Merluccius senegalensis, Mora moro, Trachyscorpia echinata, and Zenopsis conchifer. Specimens were collected during scientific trawl surveys conducted along the edge of the continental shelf of Morocco and Western Sahara in November–December 2005 and 2006. Fish were measured in relation to total length (TL, to 0.1 cm) and total weight (TW, to 1 g), and sexed when possible. All LWRs obtained for the pooled sexes gave close linear regressions (r2 ≥ 0.93), and LWR parameter b ranged from 2.638 (Z. conchifer) to 3.172 (D. calceus). Data presented herein expand the knowledge base for these species in Northwest Africa, as they have limited or no LWR data publicly available.

A single male specimen of Goneplacid crab, Carcinoplax haswelli (Miers, 1884) is recorded for the first time from the Indian Ocean. The crab specimen was collected from the trawl bycatch landing of the commercial demersal trawler operated between 30 and 150 m depth along the Gujarat coastal region, Northwest coast of India. This C. haswelli is previously recorded from northern Australia and Taiwan to South China Sea. Until now, C. haswelli is not observed or recorded from the Indian Ocean. In the present study, detailed information regarding the taxonomic identification and previous distribution of the goneplacid crab, C. haswelli is described.

Gymnocranius indicus sp. nov. is described as a new species of the fish subfamily Monotaxinae (Sparoidea: Lethrinidae), a group of commercially important species distributed throughout the Indo-West Pacific, on the basis of 16 specimens collected from the Indian Ocean. The new species shares the following characters with its western Pacific sibling, the eyebrowed large-eye seabream, G. superciliosus: elongate body, distinctive and conspicuous dark patch above the eye, prominent forehead, moderately forked caudal fin, its lobes slightly convex inside, flank silvery, and reddish-to-red dorsal, pectoral, anal and caudal fins. However, principal component analysis based on seven morphological variables distinguished most specimens from the Indian Ocean from G. superciliosus. The most influential variable in the analysis was the eye diameter, significantly larger in the new species than in G. superciliosus. All specimens of the new species that were examined also lacked blue ornamentation on the snout and cheek. At the mitochondrial cytochrome oxidase subunit-I locus, the mean genetic p-distance between the two species was 0.039. With Gymnocranius indicus sp. nov., the genus now includes 12 valid nominal species; three additional species remain undescribed.

ZooBank: urn:lsid:zoobank.org:pub:7E3750AB-D82B-4E36-B591-85C49261C379

Deep-sea hydrothermal vents host chemosynthesis-based ecosystems inhabited chiefly by specially adapted animals that do not live anywhere else, and depth has been shown to be a major driver of species composition at vents around Japan. Though the Ryukyu region in southern Japan is home to many hot vents, only two – Minami-Ensei Knoll and Yoron Hole – have been found shallower than 1000 m. Here, we report the discovery of a new vent field on the Amami Rift northwest off Amami Ōshima at 630 m deep. A total of 29 macrofaunal species were recorded from Amami Rift, including 19 vent specialists. Comparison of species composition across the three shallow Ryukyu vents revealed only three shared species, highlighting that all three display distinct community structure. Amami Rift exhibits distinct zonation patterns and is generally more similar to Minami-Ensei than Yoron Hole, but the presence of key taxa such as the sulphide worm Paralvinella and the mussel ‘Bathymodiolus’ platifrons as well as the absence of the symbiotic squat lobster Shinkaia and the limpet Lepetodrilus exemplify its difference with Minami-Ensei. Furthermore, the non-vent specific predators seen in these two sites were completely different. Overall, the Amami Rift vent field can be considered a shallow vent with a unique set of fauna, warranting future research on the mechanisms shaping disparate macrofaunal diversity between nearby shallow vents such as Amami Rift and Minami-Ensei. The unusual geological setting of Amami Rift at the converging point of Okinawa Trough and Ryukyu Arc may influence fluid chemistry to drive such differences.

Here, we report the first sighting records of Bryde's whales in Nicaragua. Four sightings were made in 2022 during boat-based surveys off the southwestern coast of Nicaragua. Photo-identification, distributional data, dive times, and behavioural information were collected, and environmental parameters, including sea surface temperature, were measured for each sighting. Sightings included calf and non-calf groups displaying travelling (n = 1; 25%), milling (n = 1; 25%), and suspected feeding (n = 2; 50%) behaviours. Approximately 4 h of focal following allowed the calculation of short and long breath intervals. Based on our observations, the individuals were suspected of feeding in the area, based on the presence of feeding birds, feeding humpback whales, relatively high time-lagged chlorophyll-a, and observed general behaviours. Our findings indicate that this species may occasionally visit Nicaraguan coastal areas in search of feeding opportunities, and could represent a possible range extension of the Eastern North Pacific stock.