Understanding the response of the Western Mediterranean cephalopods to environment and fishing in a context of alleged winners of change.

Increasing impacts of both fisheries and climate change have resulted in shifts in the structure and functioning of marine communities. One recurrent observation is the rise of cephalopods as fish recede. This is generally attributed to the removal of main predators and competitors by fishing, while mechanistic evidence is still lacking. In addition, climate change may influence cephalopods due to their high environmental sensitivity. We aim to unveil the effects of different anthropogenic and environmental drivers at different scales focusing on the cephalopod community of the Western Mediterranean Sea. We investigate several ecological indicators offering a wide range of information about their ecology, and statistically relating them with environmental, biotic and fisheries drivers. Our results highlight non-linear changes of indicators along with spatial differences in their responses. Overall, the environment drivers have greater effects than biotic and local human impacts with contrasting effects of temperature across the geographic gradient. We conclude that cephalopods may be impacted by climate change in the future while not necessary through positive warming influence, which should make us cautious when referring to them as generalized winners of current changes.

Analysis of catch rates of LED lamps using on the falling-net fishing vessels in South China Sea.

Falling nets are a type of fishing gear that appeared and developed rapidly in the northern of South China Sea in the early 1990s. We have developed Light-emitting diode (LED) fishing lamps to replace metal halide (MH) lamps that reduce fuel consumption without reducing the catches. We conducted marine light-fishing experiments in the northern South China Sea during September 20 to 26, 2019 and August 29 to 31, 2021. The results in the first fishing experiment show that there is no significant change in catch of the falling-net fishing vessel when the white LED lamps (with a total power of 36 kW) were used instead of MH lamps (with a total power of 120 kW). Coleoidea catches of the falling-net fishing vessel increased significantly when white LED lamps (with a total power of 36 kW) and cyan LED lamps (with a total power of 6.0 kW) were used. The results in the second fishing experiment show that the total weight of catches of the cyan LED fishing lamps is more than that of the white LED fishing lamps, and the cyan LED light can attract Penaeus merguiensis, Thryssa dussumieri and Sardinella zunasi more effectively than the white LED light.

Stickiness in shear: stiffness, shape, and sealing in bioinspired suction cups affect shear performance on diverse surfaces.

Aquatic organisms utilizing attachment often contend with unpredictable environments that can dislodge them from substrates. To counter these forces, many organisms (e.g. fish, cephalopods) have evolved suction-based organs for adhesion. Morphology is diverse, with some disc shapes deviating from a circle to more ovate designs. Inspired by the diversity of multiple aquatic species, we investigated how bioinspired cups with different disc shapes performed in shear loading conditions. These experiments highlighted pertinent physical characteristics found in biological discs (regions of stiffness, flattened margins, a sealing rim), as well as ecologically relevant shearing conditions. Disc shapes of fabricated cups included a standard circle, ellipses, and other bioinspired designs. To consider the effects of sealing, these stiff silicone cups were produced with and without a soft rim. Cups were tested using a force-sensing robotic arm, which directionally sheared them across surfaces of varying roughness and compliance in wet conditions while measuring force. In multiple surface and shearing conditions, elliptical and teardrop shapes outperformed the circle, which suggests that disc shape and distribution of stiffness may play an important role in resisting shear. Additionally, incorporating a soft rim increased cup performance on rougher substrates, highlighting interactions between the cup materials and surfaces asperities. To better understand how these cup designs may resist shear, we also utilized a visualization technique (frustrated total internal reflection; FTIR) to quantify how contact area evolves as the cup is sheared.

Geometric morphometrics casts light on phylogenetic relevance of cephalopod beak morphological.

The feeding organ of cephalopod species, the beak, can be used to reveal important ecological information. In this study, geometric morphometric approaches were employed to investigate the phylogenetic relevance and classification effect of beak lateral profile shape. The two-dimensional beak morphologies of 1164 pairs of 24 species from 13 genera and five families were constructed, and their evolutionary relationships and taxonomic status were confirmed using geometric morphometrics and molecular biology approaches. We also assessed the phylogenetic signals of beak shape. The analysis results show shape variation in the beak mainly in the rostrum, hood, and lateral wall. The overall shape parameters (all PCs) of the upper and lower beak are more useful for species identification. The shapes of the upper and lower beak show a strong phylogenetic signal, and the phenogram based on the beak shape basically reflected the families' taxonomic positions. We also hypothesized that the shape variation in the beaks of cephalopods may be ascribed to genetic and environmental differences. In summary, beaks are a reliable material for the classification of cephalopod species. Geometric morphometric approaches are a powerful tool to reveal the identification, phylogenetic relevance and phenotypic diversity of beak shape in cephalopods.

Plectronoceratids (Cephalopoda) from the latest Cambrian at Black Mountain, Queensland, reveal complex three-dimensional siphuncle morphology, with major taxonomic implications.

The Plectronoceratida includes the earliest known cephalopod fossils and is thus fundamental to a better understanding of the origin and early evolution of this group of molluscs. The bulk of described material comes from the late Cambrian Fengshan Formation in North China with isolated occurrences in South China, Laurentia, Kazakhstan and Siberia. Knowledge of their morphology and taxonomy is limited in that most specimens were only studied as longitudinal sections, which are prone to misinterpretations due to variations in the plane of section. We describe more than 200 new specimens, which exceeds the entire hitherto published record of plectronoceratids. The material was collected by Mary Wade and colleagues during the 1970s and 1980s, from the lower Ninmaroo Formation at Black Mountain (Mount Unbunmaroo), Queensland, Australia. Despite the collecting effort, diverse notes and early incomplete drafts, Mary Wade never published this material before her death in 2005. The specimens provide novel insights into the three-dimensional morphology of the siphuncle based on abundant material, prompting a general revision of the order Plectronoceratida. We describe Sinoeremoceras marywadeae sp. nov. from numerous, well-preserved specimens, allowing investigation of ontogenetic trajectories and intraspecific variability, which in turn enables improved interpretations of the three-dimensional siphuncle morphology. The siphuncle of S. marywadeae sp. nov. and other plectronoceratids is characterised by highly oblique segments, an elongated middorsal portion of the septal neck (= septal flap) and laterally expanded segments that extend dorsally relative to the septal flap (= siphuncular bulbs). We show that this complex siphuncular structure has caused problems of interpretation because it was studied mainly from longitudinal sections, leading to the impression that there were large differences between specimens and supposed species. We revise the order Protactinoceratida and the families Protactinoceratidae and Balkoceratidae as junior synonyms of the Plectronoceratida and Plectronoceratidae, respectively. We reduce the number of valid genera from eighteen (including one genus formerly classified as an ellesmeroceratid) to three: Palaeoceras Flower, 1954, Plectronoceras Kobayashi, 1935 and Sinoeremoceras Kobayashi, 1933. We accept 10 valid species to which the 68 previously established species may be assigned. Sinoeremoceras contains 8 of the 10 plus the new species. Two species, previously referred to ellesmeroceratid genera, are transferred to Sinoeremoceras. This revised scheme groups plectronoceratids into distinct geographically and stratigraphically separated species, which better reflects biological realities and removes bias caused by preparation techniques. North China remains important containing the highest known diversity and was likely a centre of cephalopod diversification.

The first gladius-bearing coleoid cephalopods from the lower Toarcian "Schistes Cartons" Formation of the Causses Basin (southeastern France).

The fossil record of gladius-bearing coleoids is scarce and based only on a few localities with geological horizons particularly favourable to their preservation (the so-called Konservat-Lagerstätten), which naturally leads to strongly limited data on geographical distributions. This emphasizes the importance of every new locality providing gladius-bearing coleoids. Here, we assess for the first time the gladius-bearing coleoid taxonomic diversity within the lower Toarcian "Schistes Cartons" of the Causses Basin (southeastern France). The material includes two fragmentary gladii, identified as Paraplesioteuthis sagittata and ?Loligosepia sp. indet. Just with these two specimens, two (Prototeuthina and Loligosepiina) of the three (Prototeuthina, Loligosepiina and Teudopseina) suborders of Mesozoic gladius-bearing coleoids are represented. Thus, our results hint at a rich early Toarcian gladius-bearing coleoid diversity in the Causses Basin and point out the need for further field investigations in the lower Toarcian "Schistes Cartons" in this area. This new record of Paraplesioteuthis sagittata is only the second one in Europe and the third in the world (western Canada, Germany and now France). Based on these occurrences, we tentatively suggest that P. sagittata originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

Evolutionary history influences the microbiomes of a female symbiotic reproductive organ in cephalopods.

Many female squids and cuttlefishes have a symbiotic reproductive organ called the accessory nidamental gland (ANG) that hosts a bacterial consortium involved with egg defense against pathogens and fouling organisms. While the ANG is found in multiple cephalopod families, little is known about the global microbial diversity of these ANG bacterial symbionts. We used 16S rRNA gene community analysis to characterize the ANG microbiome from different cephalopod species and assess the relationship between host and symbiont phylogenies. The ANG microbiome of 11 species of cephalopods from four families (superorder: Decapodiformes) that span seven geographic locations was characterized. Bacteria of class Alphaproteobacteria, Gammaproteobacteria, and Flavobacteriia were found in all species, yet analysis of amplicon sequence variants by multiple distance metrics revealed a significant difference between ANG microbiomes of cephalopod families (weighted/unweighted UniFrac, Bray-Curtis, P = 0.001). Despite being collected from widely disparate geographic locations, members of the family Sepiolidae (bobtail squid) shared many bacterial taxa including (~50%) Opitutae (Verrucomicrobia) and Ruegeria (Alphaproteobacteria) species. Furthermore, we tested for phylosymbiosis and found a positive correlation between host phylogenetic distance and bacterial community dissimilarity (Mantel test r = 0.7). These data suggest that closely related sepiolids select for distinct symbionts from similar bacterial taxa. Overall, the ANGs of different cephalopod species harbor distinct microbiomes and thus offer a diverse symbiont community to explore antimicrobial activity and other functional roles in host fitness.IMPORTANCEMany aquatic organisms recruit microbial symbionts from the environment that provide a variety of functions, including defense from pathogens. Some female cephalopods (squids, bobtail squids, and cuttlefish) have a reproductive organ called the accessory nidamental gland (ANG) that contains a bacterial consortium that protects eggs from pathogens. Despite the wide distribution of these cephalopods, whether they share similar microbiomes is unknown. Here, we studied the microbial diversity of the ANG in 11 species of cephalopods distributed over a broad geographic range and representing 15-120 million years of host divergence. The ANG microbiomes shared some bacterial taxa, but each cephalopod species had unique symbiotic members. Additionally, analysis of host-symbiont phylogenies suggests that the evolutionary histories of the partners have been important in shaping the ANG microbiome. This study advances our knowledge of cephalopod-bacteria relationships and provides a foundation to explore defensive symbionts in other systems.

Notes on stomach contents of pygmy and dwarf sperm whales (Kogia spp.) from around Japan.

The diets of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales in Japanese waters are poorly known. We report new information on the diets of these two species from these waters based on identifiable hard-part remains recovered from the stomach contents of 29 whales (11 pygmy and 18 dwarf sperm whales) that stranded between 1991 and 2021; those of a further two dwarf sperm whales were empty. The cephalopod (and secondarily fish and crustacean) component of the diets of these 29 whales, based on analysis of identifiable stomach-content remains, is described. The main prey includes cephalopods, represented by 1556 identifiable lower beaks (and 1483 upper beaks), crustaceans (represented by heavily digested, unidentifiable remains), and fishes (as represented by 92 otoliths). Identified prey comprises 30 species from 16 cephalopod families and 5 families from 5 fish orders. Oceanic cephalopods are the main prey of both whale species, particularly Enoploteuthis (Paraenoploteuthis) chunii and Chiroteuthis (Chirothauma) picteti. Prey diversity index values (Shannon-Weaver's diversity index H') are 2.41 for the pygmy sperm whale and 2.66 for the dwarf sperm whale. Although the main cephalopod component in the diets of these two whale species is similar, Pianka's index (0.40), a measure of niche overlap, is not that high, and may be influenced by differences in prey dominance in different feeding areas.

High-level RNA editing diversifies the coleoid cephalopod brain proteome.

Coleoid cephalopods (octopus, squid and cuttlefish) have unusually complex nervous systems. The coleoid nervous system is also the only one currently known to recode the majority of expressed proteins through A-to-I RNA editing. The deamination of adenosine by adenosine deaminase acting on RNA (ADAR) enzymes produces inosine, which is interpreted as guanosine during translation. If this occurs in an open reading frame, which is the case for tens of thousands of editing sites in coleoids, it can recode the encoded protein. Here, we describe recent findings aimed at deciphering the mechanisms underlying high-level recoding and its adaptive potential. We describe the complement of ADAR enzymes in cephalopods, including a recently discovered novel domain in sqADAR1. We further summarize current evidence supporting an adaptive role of high-level RNA recoding in coleoids, and review recent studies showing that a large proportion of recoding sites is temperature-sensitive. Despite these new findings, the mechanisms governing the high level of RNA recoding in coleoid cephalopods remain poorly understood. Recent advances using genome editing in squid may provide useful tools to further study A-to-I RNA editing in these animals.

Comparative Trophic Levels of Phragmocone-Bearing Cephalopods (Nautiloids, Ammonoids, and Sepiids).

Cephalopods are among many marine animals that through some combination of habit and/or habitat have proven difficult to study, especially understanding their trophic positions in marine communities. Stable isotope analyses have provided powerful tools for discovering quantitative aspects about the ecology and food sources of many cephalopod species. Here, we present new gut content and isotopic data (carbon and nitrogen isotopes) from phragmocone-bearing cephalopods (both ectocochleates, as well as those with internal, hard part buoyancy maintenance apparatuses). To this, we also include observations from baited remote underwater video systems to describe feeding habits and potential prey types to correlate with gut contents analyses. These data come from extant Allonautilus, Nautilus, and Sepia species, as well as from extinct nautiloids and ammonites. Extant nautiloids occupy a different isotopic niche than all other cephalopod groups where such data have been published to date. We conclude that these species are obligate scavengers rather than predators on any living species in their environments. Extant Nautilus and Allonautilus also demonstrate different patterns of functional allometry of nitrogen isotope values over ontogeny than do most other cephalopods (or animals in general), by showing decreasing nitrogen isotope levels during ontogeny. This pattern is shown to be different in Sepia and the yet small number of ammonite cephalopods studied to date, supporting the increasingly accepted view that ammonites were far closer to coleoids in basic biology than nautiloids. Overall, phragmocone-bearing cephalopods appear fundamentally different ecologically than cephalopods without this kind of buoyancy system. Of these groups, nautiloids appear to live a low-energy existence that allows them to subsist on energy-poor food sources, such as crustacean molts, as well as being able to scavenge in low oxygen basins where rare food falls, such as dead fish, remain unobtainable by most other animals.

Unusual Evolution of Cephalopod Tryptophan Indole-Lyases.

Tryptophan indole-lyase (TIL), a pyridoxal-5-phosphate-dependent enzyme, catalyzes the hydrolysis of L-tryptophan (L-Trp) to indole and ammonium pyruvate. TIL is widely distributed among bacteria and bacterial TILs consist of a D2-symmetric homotetramer. On the other hand, TIL genes are also present in several metazoans. Cephalopods have two TILs, TILα and TILß, which are believed to be derived from a gene duplication that occurred before octopus and squid diverged. However, both TILα and TILß individually contain disruptive amino acid substitutions for TIL activity, and neither was active when expressed alone. When TILα and TILß were coexpressed, however, they formed a heterotetramer that exhibited low TIL activity. The loss of TIL activity of the heterotetramer following site-directed mutagenesis strongly suggests that the active heterotetramer contains the TILα/TILß heterodimer. Metazoan TILs generally have lower kcat values for L-Trp than those of bacterial TILs, but such low TIL activity may be rather suitable for metazoan physiology, where L-Trp is in high demand. Therefore, reduced activity may have been a less likely target for purifying selection in the evolution of cephalopod TILs. Meanwhile, the unusual evolution of cephalopod TILs may indicate the difficulty of post-gene duplication evolution of enzymes with catalytic sites contributed by multiple subunits, such as TIL.

The Effect of Temperature on the Embryo Development of Cephalopod Sepiella japonica Suggests Crosstalk between Autophagy and Apoptosis.

Temperature is a crucial environmental factor that affects embryonic development, particularly for marine organisms with long embryonic development periods. However, the sensitive period of embryonic development and the role of autophagy/apoptosis in temperature regulation in cephalopods remain unclear. In this study, we cultured embryos of Sepiella japonica, a typical species in the local area of the East China Sea, at different incubation temperatures (18 °C, 23 °C, and 28 °C) to investigate various developmental aspects, including morphological and histological characteristics, mortality rates, the duration of embryonic development, and expression patterns of autophagy-related genes (LC3, BECN1, Inx4) and apoptosis marker genes (Cas3, p53) at 25 developmental stages. Our findings indicate that embryos in the high-temperature (28 °C) group had significantly higher mortality and embryonic malformation rates than those in the low-temperature (18 °C) group. Furthermore, high temperature (28 °C) shortened the duration of embryonic development by 7 days compared to the optimal temperature (23 °C), while low temperature (18 °C) caused a delay of 9 days. Therefore, embryos of S. japonica were more intolerant to high temperatures (28 °C), emphasizing the critical importance of maintaining an appropriate incubation temperature (approximately 23 °C). Additionally, our study observed, for the first time, that the Early blastula, Blastopore closure, and Optic vesicle to Caudal end stages were the most sensitive stages. During these periods, abnormalities in the expression of autophagy-related and apoptosis-related genes were associated with higher rates of mortality and malformations, highlighting the strong correlation and potential interaction between autophagy and apoptosis in embryonic development under varying temperature conditions.

Cephalopods and the law.

In this My word Daniel Osorio explains why cephalopod molluscs were protected by a European Union directive on laboratory animal legislation in 2013, and how the scientific community responded to the challenges posed by this development.

Cephalopod chemotactile sensation.

Allard et al. describe the remarkable 'taste by touch' abilities of cephalopods, in particular octopuses.

Evolution of cephalopod nervous systems.

Giant brains have independently evolved twice on this planet, in vertebrates and in cephalopods (Figure 1A). Thus, the brains and nervous systems of cephalopods provide an important counterpoint to vertebrates in the search for generalities of brain organization and function. Their mere existence disproves various hypotheses proposed to explain the evolution of the mind and the human brain, such as cognition and large brains evolved only in long-lived animals with complex social systems and parental care, none of which is true of cephalopods. Therefore, it is worthwhile to review what is known about the evolution of cephalopod nervous systems to consider how it informs our understanding of general principles of brain evolution.

Cephalopod behaviour.

Underlying all animal behaviors, from the simplest reflexive reactions to the more complex cognitive reasoning and social interaction, are nervous systems uniquely adapted to bodies, environments, and challenges of different animal species. Coleoid cephalopods - octopuses, squid, and cuttlefish - are widely recognized as the most behaviorally complex invertebrates and provide exciting opportunities for studying the neural control of behaviour. These unusual molluscs evolved over 400 million years ago from slow-moving armored forms to active predators of coastal and open ocean ecosystems. In this primer we will discuss how, during cephalopod evolution, the relatively simple ganglion-based molluscan nervous system has been extensively transformed to control the complex bodies and process extensive visual, tactile, and chemical sensory inputs, and summarize some recent findings about their fascinating behaviors.

Cephalopod versus vertebrate eyes.

Vertebrates and cephalopods are the two major animal groups that view the world through sophisticated camera-type eyes. There are of course exceptions: nautiloid cephalopods have more simply built pinhole eyes. Excellent camera type eyes are also found in other animals, such as some spider groups, a few snails, and certain marine worms, but the vast majority of large camera-type eyes belong to cephalopods and vertebrates. Vertebrates and cephalopods also devote major parts of their brains to the processing of visual information. Obviously, there are differences in eye performance among cephalopods and vertebrates, but there are no major subgroups where vision seems to have low priority. The similarity in eye geometry is striking, especially between fish and coleoid cephalopods, with a hemispherical retina centred around a spherical lens. Do these similarities mean that vertebrate and cephalopod eyes are equally good? Comparing the eyes of vertebrates and cephalopods reveals many fundamental differences with surprisingly small consequences for vision, but also one difference that means that cephalopods and vertebrates do not share the same visual world.

New species and record of Dodecaceria (Annelida: Cirratulidae) the Biological Reserve of Rocas Atoll, Brazil, the only atoll in the South Atlantic Ocean.

The polychaete Family Cirratulidae is one of the most abundant and diverse groups of Annelida, although it remains poorly known worldwide. Dodecaceria Ørsted, 1843 is one of the least described genera of Cirratulidae. The present report is the first taxonomic study of the genus Dodecaceria for the Brazilian coast. Cirratulidae were collected at Rocas Atoll, the first Brazilian marine protected area and the only atoll in the South Atlantic Ocean. We described one new species, Dodecaceria zelinhae n. sp., and a new record of D. dibranchiata Blake & Dean, 2019, previously only known from Panama. The new species is distinguished from other Dodecaceria species by having lateral tentacles, a smooth peristomium, 3-5 pairs of branchiae, hooks from chaetiger 11 in notopodia and 9 in neuropodia. Dodecaceria dibranchiata, a Caribbean species, is here recorded for the first time in the South Atlantic Ocean.

The Inner Lives of Cephalopods.

The minds of cephalopods have captivated scientists for millennia, yet the extent that we can understand their subjective experiences remains contested. In this article, we consider the sum of our scientific progress towards understanding the inner lives of cephalopods. Here, we outline the behavioral responses to specific experimental paradigms that are helping us to reveal their subjective experiences. We consider evidence from three broad research categories, which help to illuminate whether soft-bodied cephalopods (octopus, cuttlefish, and squid) have an awareness of self, awareness of others, and an awareness of time. Where there are current gaps in the literature, we outline cephalopod behaviors that warrant experimental investigation. We argue that investigations, especially framed through the lens of comparative psychology, have the potential to extend our understanding of the inner lives of this extraordinary class of animals.