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Cephalopods, a diverse class of carnivorous marine predators, exhibit a wide range of feeding behaviours and foraging strategies related to their lifestyle, habitat and morphological adaptations. Their beaks play a crucial role in capturing and processing prey. This study investigates the link between the shape of the rostrum of cephalopod beaks and their function through a mix of experimental and computational approaches. Fourteen upper beak rostrum models from a range of cephalopod species, representing their morphological and ecological diversity, were 3D-printed, and subjected to uniaxial puncture tests. Force and displacement were recorded to estimate puncture ability. Finite Element Analysis (FEA) was used to explore the form–function relationship under loading conditions mimicking biting and pulling, analysing stress patterns across different rostrum morphologies. The results show that rostrum size significantly influenced puncture performance, with smaller rostra requiring less force and displacement for puncturing. However, larger rostra exhibited higher structural stiffness, suggesting increased vulnerability to stress during biting. Morphology-driven tests demonstrated species-specific differences in puncture abilities, with rostrum sharpness playing a crucial role. FEA results further indicated that longer and sharper rostra were more susceptible to stress, potentially impacting their overall structural integrity. The findings highlight the trade-off between rostrum size and sharpness in cephalopod beaks, with implications for prey selection and feeding efficiency. The study contributes to understanding the morpho-functional aspects of cephalopod beaks and their role in prey capture and consumption, shedding light on the evolutionary pressures shaping these remarkable marine predators. [ABSTRACT FROM AUTHOR]

Morphological and molecular comparisons were made in an attempt to resolve the confusion associated with the proposed Octopus joubini species complex in the Gulf of Mexico. We utilized COI and 16S rRNA markers to determine if O. joubini represents a species complex in the northeastern Gulf of Mexico and if cryptic species were identified, to determine if they have overlapping geographical ranges. Traditional systematics and molecular evidence confirmed that O. joubini represents a complex in the northeastern GoM. We propose that O. mercatoris and O. joubini continue to be considered a species complex due to a small sample size and subtle morphological differences observed in the present study. It is still uncertain if Forsythe and Toll’s (1991) “large egg” species represents a third species in the complex or is conspecific with O. mercatoris. The two species appear to have broad distributions with overlapping geographical ranges. Future research would benefit from a larger sample size that would include organisms from the northern GoM where Forsythe and Toll (1991) collected their “small” and large egg species. [ABSTRACT FROM AUTHOR]

Understanding senescence in semelparous species not only deepens our knowledge of the evolution of aging but also highlights the diversity of life strategies that have evolved in the natural world. This terminal phase occurs at the end of the lifecycle and is particularly evident in the common octopus, Octopus vulgaris , Cuvier 1797, a semelparous species with terminal reproduction. The aim of the present work was to document the natural process of senescence in specimens raised in captivity for two consecutive generations and the differences in morphology, behaviour and functional traits between the two sexes. Both sexes showed similar affections in the skin, with unhealed wounds, paler colors, and white lesions. At the same temperature males lived longer (six to seven months) than females, and showed extensive arm tip damage, with the exception of the hectocotylus that was fully functional until the very last day. Females, contrarily to males, lose 35.4–46.8% of their body weight during brooding and senescence. Uncommon behaviours were registered during this terminal phase like egg laying outside of the den, egg ingestion or copulation between males. These observations provide new data that will help to better understand this terminal phase and the natural processes occurring in both sexes at the end of their life cycle. • Octopus vulgaris female life span is shorter than that of males at the same temperature. • Senescence comes earlier and is more apparent in O. vulgaris females than in males. • Octopus males suffer necrosis of all arm tips except in the sexual arm (hectocotylus). • Males of O. vulgaris are reproductively fully functional until their very last day. [ABSTRACT FROM AUTHOR]

Cephalopods are important in midwater ecosystems of the Gulf of Mexico (GOM) as both predator and prey. Vertical distribution and migration patterns (both diel and ontogenic) are not known for the majority of deep-water cephalopods. These varying patterns are of interest as they have the potential to contribute to the movement of large amounts of nutrients and contaminants through the water column during diel migrations. This can be of particular importance if the migration traverses a discrete layer with particular properties, as happened with the deep-water oil plume located between 1000 and 1400 m during the Deepwater Horizon (DWH) oil spill. Two recent studies focusing on the deep-water column of the GOM [2011 Offshore Nekton Sampling and Analysis Program (ONSAP) and 2015–2018 Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND)] program, produced a combined dataset of over 12,500 midwater cephalopod records for the northern GOM region. We summarize vertical distribution patterns of cephalopods from the cruises that utilized a 10 m2 Multiple Opening/Closing Net and Environmental Sensing System (MOC10). About 95% of the cephalopods analyzed here either move through or live within 1000–1400 m zone. Species accounts include those with synchronous (e.g., Pterygioteuthis sp.) and asynchronous (e.g., Stigmatoteuthis arcturi) vertical migration. Non-migration patterns of some midwater cephalopods (e.g., Vampyroteuthis infernalis) are also highlighted. Ontogenic shifts are noted for some species examined.

The biodiversity of mollusks, particularly cephalopods, has not been exhaustively determined in the Revillagigedos ecoregion, which is a biodiversity hotspot for several marine groups located in the Tropical East Pacific Province. In our study, we detected and examined ocellate octopuses from Socorro and Clarion Islands, and determined their identity using morphological criteria and molecular data from two mitochondrial genes (COIII and COI). The taxon identified was Octopus oculifer, a species considered endemic to the Galapagos Archipelago. In addition, according to our analyses, O. mimus, O. hubbsorum and O. oculifer are very closely related and may represent a species complex comprised of three morphotypes. We found that the evolutionary relationships among octopuses are not determined by the presence of ocelli. This study is the first to report a clade represented by ocellate and non-ocellate species, in addition, the identity of cephalopods in the Revillagigedos was determined with analytical support. [ABSTRACT FROM AUTHOR]

Species of the genus Octopus from the northeastern Pacific are ecologically and economically important; however, their taxonomy is confusing and has not been comprehensively assessed. In this study, we performed a taxonomic evaluation of these species considering the morphological characteristics of the original descriptions, a molecular analysis of partial COI-gene sequences, and a traditional morphometry analysis of nine body measurements. Several interesting findings were obtained with our results: for instance, we updated the diagnoses of some species by including characters such as the number of lamellae per demibranch and the presence of chromatophores in the visceral sac; we deposited partial COI-gene sequences of species that had not been incorporated into the GenBank repository; and according to the morphometric analysis, we confirmed that the lengths of arms I–IV are relevant to discriminate the species under study. The taxa evaluated were morphologically, molecularly and morphometrically well-delimited; however, features such as funnel organ shape and arm length proportions in regard to dorsal mantle length are either not included in the diagnosis of the genus Octopus or overlap with other genera. Hence, this information, combined with the results obtained from the molecular analysis, supports the generic re-assignation of two of the species evaluated.

Octopus hubbsorum is a commercially important species from the Mexican Pacific, but aspects of its reproductive biology have been scarcely studied. Several studies have investigated the macroscopic and histological features of the reproductive system of octopods, focusing primarily on the ovary and its maturation process, but histological descriptions of the entire reproductive system in both sexes are not available. In this study, we provide detailed morphological and histological descriptions of male and female reproductive systems of O. hubbsorum locating and characterizing each of their constituent parts. Morphological features that are different among species are highlighted, as the location of the common oviduct has not been previously reported for this species, nor the differences in the epithelium of the male reproductive system. [ABSTRACT FROM AUTHOR]

Species of the genus Octopus from the northeastern Pacific are ecologically and economically important; however, their taxonomy is confusing and has not been comprehensively assessed. In this study, we performed a taxonomic evaluation of these species considering the morphological characteristics of the original descriptions, a molecular analysis of partial COI-gene sequences, and a traditional morphometry analysis of nine body measurements. Several interesting findings were obtained with our results: for instance, we updated the diagnoses of some species by including characters such as the number of lamellae per demibranch and the presence of chromatophores in the visceral sac; we deposited partial COI-gene sequences of species that had not been incorporated into the GenBank repository; and according to the morphometric analysis, we confirmed that the lengths of arms I–IV are relevant to discriminate the species under study. The taxa evaluated were morphologically, molecularly and morphometrically well-delimited; however, features such as funnel organ shape and arm length proportions in regard to dorsal mantle length are either not included in the diagnosis of the genus Octopus or overlap with other genera. Hence, this information, combined with the results obtained from the molecular analysis, supports the generic re-assignation of two of the species evaluated. [ABSTRACT FROM AUTHOR]

Ostracods are common yet understudied prey item in the fossil record. We document drill holes in Paleocene (Danian) ostracods from central Argentina using 9025 specimens representing 66 species. While the percentage of drilled specimens at assemblage‐level is only 2.3%, considerable variation exists within species (0.3–25%), suggesting prey preference by the drillers. This preference is not determined by abundance because no significant correlation is found between species abundance and drilling percentages. Seven methods were used, some of which are new, to quantify drilling percentages for the abundant and commonly drilled Togoina argentinensis. The resulting range, from 9.9% to 14.6%, suggests that drilling percentages are fairly insensitive to the method used, implying that comparisons across studies are possible. This information, combined with data from the literature, suggests the Cretaceous–Palaeogene mass extinction may have had a limited effect on drilling intensity in ostracods. The cylindrical (Oichnus simplex) and parabolic (O. paraboloides) drill holes from Argentina may have been caused primarily by naticid and possibly muricid gastropods. Two oval drill holes (O. ovalis) are morphologically similar to octopod drill holes, but their small size, the fact that extant octopods are not known to drill ostracods and the absence of such holes in co‐occurring gastropods, preclude ascription to a predator clade. Drill holes are located preferentially in the median and dorsal regions, where most soft tissue, including the adductor muscle, is located. Drilled specimens are statistically taller than non‐drilled specimens for T. argentinensis and larger predators selected larger ostracods. The drilling percentage does not significantly differ in ornamented ostracods. [ABSTRACT FROM AUTHOR]

Email is an important service to exchange information for Internet users, this important use of email made it the target of various disturbances, such as spam attacks, most of the time it's generated by advertising (Clayton 2003). Short Message Service (SMS) like emails are also the target of spam attacks, so it is necessary to make emails and messages safe from spams (Karami and Zhou 2014). This motivates the researchers to provide new solutions which can filter and detect spams based on heuristic techniques represented by the inspiration from nature (or bio-inspiration), it's a new discipline that studies the best ideas of nature, then imitates them and applies their concepts and processes to human problems (Tahir et al. 2017, Ferreira et al. 2014), after exploring the marine world we opted for the octopods, because of its high quality of defense, and even are not very used in the world of bio-inspiration. One of the most defensive animals in their life is the octopods, they have a great ability to avoid attacks from predators, and they make an intelligent system of security that is hard to break it (Octopus-defenses 2018). In our work we proposed a technique based on the natural function of the octopod for the purpose of detect spam sms, the technique is based on two objective functions, the first is to calculate the force of move of each message, and the second is the probability of messages of each class from the learning base. [ABSTRACT FROM AUTHOR]

In this paper, we studied both kinematic and dynamic models of a mammal-like octopod robot. To control robot legs, we employed a simple gait generator based on a sine function and we proposed modified generators of gait. The introduced generators allowed us to obtain better kinematic and dynamic properties of motion of the whole robot during walking. By changing the length and the height of a single robot step, it is possible to use one model to control the initial, regular, and final phases of the robot gait without the need of generating additional control signals. The simulation parameters were estimated based on the prototype designed in Inventor software. In turn, for numerical research, we used a simulation model implemented in Mathematica. The obtained results were presented in the form of time histories of basic kinematic and dynamic quantities of the robot gait as well as the configuration of the robot legs at the chosen time moments. The presented method allows us to precisely control the robot position in the vertical direction, which is also presented in this paper. As a result, we obtained better stability of the whole robot during walking and performing tasks, also on slippery terrains, i.e. on terrains with relatively low coefficient of friction between the ground and the robot feet. [ABSTRACT FROM AUTHOR]

The goal of the study was to perform both kinematic and dynamic simulation of an octopod robot walking on a flat and hard surface. To drive robot legs, different non-linear mechanical oscillators were employed as central pattern generators. Aside from using some well-known oscillators, a new model was proposed. Time series of robot's kinematic and dynamic locomotion parameters were computed and discussed. Displacement and velocity of the centre of gravity of the robot, ground reaction forces acting on the robot legs, as well as some aspects of energy consumption of a walking robot were analysed to assess the central pattern generators. The obtained kinematic and dynamic parameters showed some advantages of the applied generator. In particular, the gait of the robot was most stable when the robot was driven by the proposed central pattern generator model. [ABSTRACT FROM AUTHOR]

Abstract Tetrodotoxin is a potent non-proteinaceous neurotoxin, which is commonly found in the marine environment. Synthesised by bacteria, tetrodotoxin has been isolated from the tissues of several genera including pufferfish, salamanders and octopus. Believed to provide a defensive function, the independent evolution of tetrodotoxin sequestration is poorly understood in most species. Two mechanisms of tetrodotoxin resistance have been identified to date, tetrodotoxin binding proteins in the circulatory system and mutations to voltage gated sodium channels, the binding target of tetrodotoxin with the former potentially succeeding the latter in evolutionary time. This review focuses on the evolution of tetrodotoxin acquisition, in particular how it may have occurred within the blue-ringed octopus genus (Hapalochlaena) and the subsequent impact on venom evolution. [ABSTRACT FROM AUTHOR]

Abstract: Using a combination of diverse large predatory fishes and one seabird, we collected information on the cephalopod fauna of the western Indian Ocean. We analyzed the stomach contents of 35 fishes representing ten families (Xiphiidae, Istiophoridae, Scombridae, Carangidae, Coryphaenidae, Alepisauridae, Dasyatidae, Carcharhinidae, Alopiidae and Sphyrnidae) and of the sooty tern Onychoprion fuscata of the Mozambique Channel from 2000 to 2010. Both fresh and accumulated beaks were used for identifying cephalopod prey. Cephalopods were important prey for twelve predators; swordfish Xiphias gladius had the highest cephalopod proportion; sooty tern (O. fuscata) and bigeye tuna (Thunnus obesus) had high proportions too. We recovered 23 cephalopod families and identified 38 species. Ten species from four Teuthida families (Ommastrephidae, Onychoteuthidae, Histioteuthidae and Ancistrocheiridae) and two Octopoda families (Argonautidae and Bolitaenidae) occurred very frequently in the stomach contents, while Sepiida were rare. Ommastrephidae were the most cephalopod food sources: the purpleback flying squid Sthenoteuthis oualaniensis was the most prevalent prey by far, Ornithoteuthis volatilis was important for eleven predators and few but large specimens of the neon flying squid Ommastrephes bartramii were recovered in the stomachs of swordfish in the Indian South Subtropical Gyre province only. Predators' groups were identified based on cephalopod prey composition, on depth in which they forage, and on prey size. Surface predators' diets were characterized by lower cephalopod diversity but greater average numbers of cephalopod prey, whereas the deep-dwelling predators (swordfish and bigeye tuna) preyed on larger specimens than surface predators (O. fuscata or yellowfin tunas Thunnus albacares). Our findings emphasized the usefulness of a community of marine predators to gain valuable information on the biology and the distribution of the cephalopod forage fauna that are discussed with regard to biogeographic province, marine predator, fishing gear to catch the large pelagic fishes, and size of the beaks recovered in the stomachs. [Copyright &y& Elsevier]

Repeated cycles of glaciation have had major impacts on the distribution of genetic diversity of the Antarctic marine fauna. During glacial periods, ice cover limited the amount of benthic habitat on the continental shelf. Conversely, more habitat and possibly altered seaways were available during interglacials when the ice receded and the sea level was higher. We used microsatellites and partial sequences of the mitochondrial cytochrome oxidase 1 gene to examine genetic structure in the direct-developing, endemic Southern Ocean octopod Pareledone turqueti sampled from a broad range of areas that circumvent Antarctica. We find that, unusually for a species with poor dispersal potential, P. turqueti has a circumpolar distribution and is also found off the islands of South Georgia and Shag Rocks. The overriding pattern of spatial genetic structure can be explained by hydrographic (with ocean currents both facilitating and hindering gene flow) and bathymetric features. The Antarctic Peninsula region displays a complex population structure, consistent with its varied topographic and oceanographic influences. Genetic similarities between the Ross and Weddell Seas, however, are interpreted as a persistent historic genetic signature of connectivity during the hypothesized Pleistocene West Antarctic Ice Sheet collapses. A calibrated molecular clock indicates two major lineages within P. turqueti, a continental lineage and a sub-Antarctic lineage, that diverged in the mid-Pliocene with no subsequent gene flow. Both lineages survived subsequent major glacial cycles. Our data are indicative of potential refugia at Shag Rocks and South Georgia and also around the Antarctic continent within the Ross Sea, Weddell Sea and off Adélie Land. The mean age of mtDNA diversity within these main continental lineages coincides with Pleistocene glacial cycles. [ABSTRACT FROM AUTHOR]

Amphioctopus fangsiao is an important fishery resource in northern coastal China, and this species has been developed for commercial fishing and aquacultural purposes. However, its embryos are vulnerable to ambient temperature, which leads to challenges in resource management and conservation. The present study investigated how high temperatures could affect the embryonic development (e.g., morphology, development time, and viability) of A. fangsiao. The results showed that the embryonic developmental rate was accelerated as the temperature increased. In addition, temperatures higher than the thermal threshold detrimentally affected the morphology and viability of eggs. Embryos maintained at 18, 21, and 24 ℃ successfully hatched at 40, 30, and 24 d after spawning, respectively. However, no embryos hatched at 27 ℃. Elevated temperatures altered the trajectory of normal embryonic development and increased the percentage of eggs with abnormal morphology. Embryos maintained at 24 ℃ failed to undergo the second inversion during embryonic development and remained at the animal pole until stage XVII (15 d). Upon the completion of organogenesis at stage XIX, an elevated temperature, as the external stimulus, could promote the early hatching of embryos with poor physiological features (e.g., small size and large yolk sac). The results indicate that the thermal range for A. fangsiao embryonic development is 18–24 ℃. Our findings on the relationship between embryonic stage and temperature might help fishery managers predict the emergence time of the hatchling population and promote the conservation of this species when establishing related fishery policies. [ABSTRACT FROM AUTHOR]