Octopus Cyanea Research Articles

The role of women in community-based small-scale fisheries management: the case of the southern Madagascar octopus fishery

Ensuring that benefits from natural resource management initiatives are shared amongst both men and women is crucial to achieving long-term conservation objectives. In southwest Madagascar, community-managed temporary closures of octopus ( Octopus cyanea) fisheries have become a popular approach to resource management, and have been shown to increase catches with lasting results. Women account for well over half of octopus fishers regionally, and are heavily influenced by efforts to manage the resource. We assess the role of gender in this fisheries management initiative, comparing fisheries landings for men and women over a seven-year period, and assessing female involvement in the management process through a series of focus groups and workshop discussions. Our findings show that, while both genders benefit from the fisheries management initiative, men tend to harvest bigger octopus and dominate reserve management discourse and decision-making. We discuss these findings in relation to other natural resource management initiatives and recommend strategies to ensure better integration of women in octopus fishery management.

Varying degrees of polarization vision in octopus: interaction between degree and angle of polarization in contrast detection tasks

Event Abstract Back to Event Varying degrees of polarization vision in octopus: interaction between degree and angle of polarization in contrast detection tasks Shelby E. Temple1, 2*, Julian Partridge1, Justin Marshall3 and Nicholas W. Roberts1 1 The University of Bristol, School of Biological Sciences, United Kingdom 2 The University of Queensland, School of Biomedical Sciences, Australia 3 The University of Queensland, Queensland Brain Institute, Australia Sensitivity to the polarization of light is common among invertebrates, and cephalopods are no exception. Previous behavioural and electrophysiological evidence suggests that cuttlefish, octopus and squid have acute discrimination of electric field vector (e-vector) angular contrast (as low as one degree). However, like many studies of polarization vision, cephalopods have only been tested under strongly polarized light conditions i.e. where the degree of polarization was close to 100 per cent. Because multiple scattering events reduce the degree of polarization of the underwater light field, we were curious to know how lower degrees of polarization affect polarization vision in cephalopods. Using a modified liquid crystal display monitor, which presents images in polarization rather than luminosity, we measured a threshold curve of the minimum angular difference between e-vectors that was just detectable over a range of degrees of polarization for two octopus species. We used the sudden change in body colouration in response to a looming stimulus presented onscreen as an indication of detection. Both species (Octopus cyanea and Adopus aculeatus) were able to discriminate a stimulus from the background when the difference in e-vector angle was less than 5 degrees, and they could continue to do so when the degree of polarization decreased to as low as 30 per cent. Below this level the minimum angular contrast that they could distinguish rapidly increased, until, at a degree of polarization of less than 5 per cent an angular contrast of over 50 degrees was required to elicit a behavioural response. We conclude that octopuses are able to continue to use their polarization sensitivity even when the degree of polarization in the visual information is low. However, there is a trade off against the minimum angular difference between e-vectors they can detect. This is perhaps to be expected given that our measurements of the polarization signals in the aquatic world are showing that the degree of polarization is typically below 40 per cent. The remarkable abilities of these polarization specialists is driving the development of ever more sensitive and accurate polarization imaging techniques as we endeavor to understand the visual ecology of these fascinating animals. Acknowledgements Yulgilbar Foundation Fellowship to Lizard Island Research Station Air Force Office of Scientific Research, U.S.A. Biotechnology and Biological Sciences Research Council, U.K. Thanks to the staff at the Lizard Island Research Station, Roy Caldwell, and Megan Porter Keywords: Opsin, Polarisation, Visual Neuroscience, Visual ecology, bio-inspired nanotechnology, Behavioural Ecology, Neuroethology Conference: International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013. Presentation Type: Oral presentation preferred Topic: Colour and polarisation vision Citation: Temple SE, Partridge J, Marshall J and Roberts NW (2019). Varying degrees of polarization vision in octopus: interaction between degree and angle of polarization in contrast detection tasks. Front. Physiol. Conference Abstract: International Conference on Invertebrate Vision. doi: 10.3389/conf.fphys.2013.25.00072 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Feb 2013; Published Online: 09 Dec 2019. * Correspondence: Dr. Shelby E Temple, The University of Bristol, School of Biological Sciences, Bristol, United Kingdom, shelby.temple@bristol.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Shelby E Temple Julian Partridge Justin Marshall Nicholas W Roberts Google Shelby E Temple Julian Partridge Justin Marshall Nicholas W Roberts Google Scholar Shelby E Temple Julian Partridge Justin Marshall Nicholas W Roberts PubMed Shelby E Temple Julian Partridge Justin Marshall Nicholas W Roberts Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

An inter-specific behavioural association between a highfin grouper (Epinephelus maculatus) and a reef octopus (Octopus cyanea)

Groupers and reef octopus are economically and ecologically important predators on Indo-Pacific coral reefs and known as solitary hunters. Here we describe a highly unique and unusual observation of a behavioural non-random association between the highfin grouper (Epinephelus maculatus) and the reef octopus (Octopus cyanea) in the Great Barrier Reef. Such an observation is highly novel given that the association crosses both the phyla and the invertebrate to vertebrate divide. The present study hypothesizes that the association is non-random and potentially the result of cooperative hunting but as such this requires further evidence and testing.

Using Age-Based Life History Data to Investigate the Life Cycle and Vulnerability of Octopus cyanea

Octopus cyanea is taken as an unregulated, recreationally fished species from the intertidal reefs of Ningaloo, Western Australia. Yet despite its exploitation and importance in many artisanal fisheries throughout the world, little is known about its life history, ecology and vulnerability. We used stylet increment analysis to age a wild O. cyanea population for the first time and gonad histology to examine their reproductive characteristics. O. cyanea conforms to many cephalopod life history generalisations having rapid, non-asymptotic growth, a short life-span and high levels of mortality. Males were found to mature at much younger ages and sizes than females with reproductive activity concentrated in the spring and summer months. The female dominated sex-ratios in association with female brooding behaviours also suggest that larger conspicuous females may be more prone to capture and suggests that this intertidal octopus population has the potential to be negatively impacted in an unregulated fishery. Size at age and maturity comparisons between our temperate bordering population and lower latitude Tanzanian and Hawaiian populations indicated stark differences in growth rates that correlate with water temperatures. The variability in life history traits between global populations suggests that management of O. cyanea populations should be tailored to each unique set of life history characteristics and that stylet increment analysis may provide the integrity needed to accurately assess this.

Individual prey choices of octopuses: Are they generalist or specialist?

Abstract Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affecting prey choice. Two methods were used, an assessment of the extent to which an individual octopus made choices of species representative of those population (PSi and IS) and 25% cutoff values for number of choices and percentage intake of individual on their prey. In one population of Octopus cf vulgaris in Bermuda individuals were generalist by IS=0.77, but most chose many prey of the same species, and were specialists on it by >75% intake. Another population had a wider prey selection, still generalist with PSi=0.66, but two individuals specialized by choices. In Bonaire, there was a wide range of prey species chosen, and the population was specialists by IS= 0.42. Individual choices revealed seven specialists and four generalists. A population of Octopus cyanea in Hawaii all had similar choices of crustaceans, so the population was generalist by IS with 0.74. But by individual choices, three were considered a specialist. A population of Enteroctopus dofleini from Puget Sound had a wide range of preferences, in which seven were also specialists, IS=0.53. By individual choices, thirteen were also specialists. Given the octopus specialty of learning during foraging, we hypothesize that both localized prey availability and individual personality differences could influence the exploration for prey and this translates into different prey choices across individuals and populations showed in this study.

Camouflaging in a complex environment--octopuses use specific features of their surroundings for background matching.

Living under intense predation pressure, octopuses evolved an effective and impressive camouflaging ability that exploits features of their surroundings to enable them to “blend in.” To achieve such background matching, an animal may use general resemblance and reproduce characteristics of its entire surroundings, or it may imitate a specific object in its immediate environment. Using image analysis algorithms, we examined correlations between octopuses and their backgrounds. Field experiments show that when camouflaging, Octopus cyanea and O. vulgaris base their body patterns on selected features of nearby objects rather than attempting to match a large field of view. Such an approach enables the octopus to camouflage in partly occluded environments and to solve the problem of differences in appearance as a function of the viewing inclination of the observer.

Molecular identification of three co-occurring and easily misidentified octopus species using PCR–RFLP techniques

Octopus vulgaris, Octopus cyanea and Callistoctopus ornatus may co-occur in near-shore shallow reef habitats across the Southwestern Indian Ocean. All three species are harvested, both by small vessels and individual spearfishers and are of considerable socio-economic importance. Phenotypic-based discrimination of the three species is unreliable and at present species-specific catch data are not collected, preventing evaluation of species specific fisheries effects. In light of increasing exploitation rates the development of an unambiguous means of species discrimination is required for sustainable management and conservation of species and intraspecific stocks. In this study, a simple, cost effective, molecular technique to differentiate the three species is described.

The reproductive cycle of Octopus cyanea in southwest Madagascar and implications for fisheries management

The Octopus cyanea fishery is the most economically important fishery in southwest Madagascar. Growing concerns over the sustainability of exploitation have promoted a number of conservation efforts to improve management of the fishery. We analyse one year of catch data to identify seasonal variations in sexual maturity and key reproductive periods of the species, using microscopic analysis of gonad tissues to validate field assessments of maturity. Data show seasonal variability in maturity and size at first maturity for both sexes, as well as temporal changes in the sex ratio of the species. Maturity occurred at a minimum mean weight of 2246g for females and 643g for males. A clear relationship between gonad weight and total weight in male octopus indicates that total weight can be used as a proxy for sexual maturity in males. Conversely, females show high variability in weight at first maturity and no clear relationship between total weight and maturity stage. Fully sexually mature females were very rare, constituting less than 1% of the total sample. We hypothesise that the artisanal fishery may not be currently exploiting mature female individuals because females retreat to deeper waters prior to reproduction, thus remaining beyond the reach of the fishery. An abundance of juvenile individuals in the catch from June, and again from October to November, indicates recruitment peaks at these two times. In recent years, management of this species in southwest Madagascar has focused on short-term closures to fishing within specific tidal reef flat areas. Identification of the key phases of the reproductive cycle of O. cyanea in southwest Madagascar may provide managers with biological evidence to support seasonal closures designed to protect key life stages of the species.

Sexual cannibalism by Octopus cyanea on a Pacific coral reef

Sexual cannibalism is rare in the animal kingdom. Although cannibalism is not uncommon in cephalopods, here we report the first documented case of sexual cannibalism. A large female Octopus cyanea was observed continuously for 2.5 days in Palau, Micronesia, when she was out of her den. On the second day, a small male followed and mated her 13 times during 3.5 h while she continued to forage over 70 m distance. After the 12th mating, she aggressively chased a different small octopus that barely escaped by jetting, inking and swimming upwards. Shortly thereafter, the original small male mated her a 13th time, but subsequently she attacked and suffocated him and spent 2 days cannibalizing him in her den. This sort of intraspecific aggression helps to explain several reports of octopuses mating out in the open, a behaviour that may serve to allow the smaller mate to escape cannibalism.

Ethogram of Abdopus aculeatus (d'Orbigny, 1834) (Cephalopoda: Octopodidae): Can behavioural characters inform octopodid taxomony and systematics?

An ethogram is provided for the small, intertidal, diurnal octopus Abdopus aculeatus (d’Orbigny, 1834). Information is based primarily on in situ observations of adults, and supplemented with photographs of animals in aquaria. Aspects of the dymantic display, mating system, activity patterns, and habitat use appear similar to those expressed by other members of Abdopus, as well as the large sister taxon Octopus cyanea, suggesting that these behaviours may be conserved throughout the evolution of these octopuses. Many skin components are also shared with Octopus bimaculoides, which may reflect either an evolutionary affinity with this octopus, or convergence in these characters. If behavioural units such as those documented here are compiled in a consistent manner for other species, then they may facilitate taxonomic identification, as well as future evolutionary studies of octopodids.

Apparent movement in a visual display: the ‘passing cloud’ of Octopus cyanea (Mollusca: Cephalopoda)

AbstractThe tremendous capacity of the chromatophore system in cephalopod skin to change its colour across space and time has allowed these animals to produce complex visual displays to conspecific and heterospecific targets, including the aptly‐named ‘passing cloud’. This display has been suggested as an interspecies communication, but it has not been investigated in detail. Octopus cyanea produced dark passing clouds during hunting of crab prey, typically after a web‐over capture attempt. Clouds moved not randomly but forward along the mantle, over the head and down the outstretched arm web, and were often accompanied by white margins that enhanced their appearance by intensity contrast. This visual display is presumed to be a startle attempt, producing apparent movement by selective sequential chromatophore expansion to induce a crab to move without the drawback of motion by the octopus itself.

The Artisanal Fishery for Octopus cyanea Gray in Tanzania

Preliminary results for the artisanal fisheries of Octopus cyanea Gray (1849) in Tanzania are provided for the period April 2000 until June 2001. A total of 2546 individual catches and 15473 specimens were analyzed from 3 sites located at Tanga, Mafia Island, and Mtwara. Size range, average weight and catch per unit effort (CPUE) were all significantly lower at Tanga and Mtwara compared to Mafia indicating that the former sites may be overfished. Abundance of smaller individuals was higher at Tanga and Mtwara, but overall biomass was lower. Octopi at each site exhibited allometric growth as indicated by analyses of the length-weight relationships. Females become sexually mature at a minimum weight of 600 g while for males the minimum weight was 320 g. Higher numbers of mature individuals were found in June of both years and correlate with peaks in the gonosomatic index. Recruitment peaked a few months after brooding periods. Sex ratios indicate females may be more prone to capture during brooding periods. Reasons for differences between sites are discussed.

Nutrient, fatty acid, amino acid and mineral analysis of natural prey of the Hawaiian monk seal, Monachusschauinslandi

Proximate nutrients, gross energy content, mineral, amino acid and fatty acid composition were determined for teleost, cephalopod and crustacean prey of the Hawaiian monk seal. Crude protein was highest in the octopus, Octopus cyanea (80.0%), crude fat was highest in the Muraenid teleost, Gymnothorax eurostus (14.1%), whereas crude ash was highest in the lobster, Panulirus marginatus (11.6%). Gross energies ranged from 4.0±0.01 kcal g −1 in the Labrid teleost Bodianus bilulunatus to 6.0±0.12 kcal g −1 in the moray eel, Gymnothorax undulatus. Essential amino acids occurred in lower concentrations as a percentage of the total amino acids (35.8±2.6%) than non-essential amino acids (64.2±2.6%), but the ratio of individual amino acids to total amino acid concentrations were similar to those required by some monogastric terrestrial species and fingerling salmon. The fatty acid concentrations varied widely among species (range=1.2–16.5 mg 100 mg −1); however, the teleosts had higher total fatty acids than the non-teleosts. This study indicates that, from a nutritional standpoint, some prey may be more beneficial to the Hawaiian monk seal; however, these prey are not necessarily the most abundant or available to some populations of the monk seal.

Foraging and associated behavior by Octopus cyanea Gray, 1849 on a coral atoll, French Polynesia

Individual Octopus cyanea Gray, 1849 were observed continuously while foraging over a 6 day period during daylight hours. Foraging usually occurred once early in the morning and once late in the afternoon, and successive forages did not duplicate the same routes. On average, single forages ( n = 16) covered 81 m (max. 129 m), lasted 118 min (max. 6 h), and often included up to five types of substrata. Octopuses spent about 28% of daylight hours foraging, usually in a saltatory (stop and go) search strategy. Small fishes (five species) often followed foraging octopuses. Foraging was tactile and speculative: octopuses either pounced on a likely object with the web spread, or groped deeply into crevices with the long arms, according to substratum. No octopus was observed to make direct, visually guided attacks on prey. These field observations suggest that their keen eyesight is used for determining the foraging path, scanning for predators, matching the substrata for crypsis, and finding their way back to their dens.

Appetitive conditioning in Octopus cyanea..

The performance of Octopus cyanea was studied in 3 appetitive conditioning situations. In Experiment 1, 2 groups were trained in a runway; a large reward produced faster acquisition when reinforcement was consistent and better subsequent performance on a partial schedule than did a small reward. In Experiment 2, activity in the vicinity of a feeder was measured, and in Experiment 3, latency and probability of response were measured in an automated version of a traditional conditioned attack situation (Boycott & Young, 1950). There was evidence of acquisition with continuous reinforcement in both experiments but in neither with partial reinforcement. All of the results can be understood in terms of growth and decline in the strength of stimulus-reinforcer associations with reinforcement and nonreinforcement.

Appetitive conditioning in Octopus cyanea.

Appetitive conditioning in Octopus cyanea.

Octopus mantle citrate synthase.

Citrate synthase (EC 4.1.3.7) in mantle muscle of the octopus, Octopus cyanea, occurs in relatively low specific activity and is largely independent of pH between 7.5 and 9.0. Catalytic activity is regulated by the adenylate energy charge and by at least two Krebs cycle intermediates, α-ketoglutarate and citrate. Of the adenylates, ATP is by far the most potent inhibitor, at near-physiological concentrations (4 mM), causing almost a 20-fold increase in the Michaelis constant for acetyl-CoA. Citrate and α-ketoglutarate, on the other hand, are competitive with respect to oxaloacetate, rather than acetyl-CoA, and bring about large increases in the Michaelis constant for oxaloacetate. The regulatory properties of citrate synthase allow a curtailment of carbon flow into the Krebs cycle during periods of burst muscle work, when mantle anaerobic glycolysis is strongly activated.

Growth and life‐span of Octopus cyanea (Mollusca: Cephalopoda)*

The growth of Octopus cyanea was followed from 67 to 6500 g in captivity on an ad libitum diet of live crabs. Females spawning in captivity always die after the eggs hatch. Males may mate many times with several different females but do not appear to outlive females. The species spawns throughout the year; the time of spawning is probably determined by the age of the female. Males stop growing after suckers at the edge of the web enlarge and gradually lose weight until their death, about two or three months after maximum sucker enlargement. The life‐span of O. cyanea appears to be between 12 and 15 months from settlement.A growth curve is presented for the species from settling to maximum size and compared with experimental data on captive and marked, free‐living animals. Free octopuses grew at rates similar to captives fed ad libitum, indicating that food was not limiting to growth in the field, and that a reasonable estimate of age could be obtained from the weight at capture.A method of marking animals by branding is described which gives lifetime scars making it possible to study the growth of individual animals released in the field.

Observations on the feeding, growth rate and habits of newly settled Octopus cyanea

This paper records observations on the behaviour ofOctopus cyuneu caught in Hawa shortly after settlement from the plankton. The young animals rapidly establish “homes” on the bottom and defend these against their own species. Of a variety of food offered, crabs were most frequently (nearly always) taken; the animals always took the prey home to eat it. Records of diurnal activity show morning and evening peaks as in adults. There was a steady 2–3.5% daily increase in weight over the first six months (July‐January) after settlement

The Oxygen Consumption of Octopus Cyanea

ABSTRACT There is now a considerable literature on the brain and behaviour of Octopus (for reviews see Wells, 1966; Young, 1964). Most of the accounts relate to the mediterranean Octopus vulgaris and most are concerned with this animal’s behaviour in training experiments and with the effect of brain lesions on learning. These experiments have been made with octopuses of a variety of sizes, ranging from 500 g. (early experiments by Boycott & Young, 1950−55; see reviews cited above) through a ‘normal’ experimental range of 200−400 g. down to the 15−40 g. animals used in experiments dealing with statocyst removal and recognition of the orientation of objects in the visual field (Rowell & Wells, 1961 ; Wells, 1960).