Academic literature on the topic 'Benthic cephalopods'

Despite the important ecological role of cephalopods in energy and material flow in marine ecosystems, they are poorly understood, particularly those inhabiting deep-sea bottoms below 800 m. To define cephalopod species assemblages from the upper to the lower slope, we conducted 13 oceanographic and trawl surveys in the Balearic basin (NW Mediterranean) in 1985–92 and 2007–10 at depths between 450 and 2200 m. Multivariate analysis suggests the existence of three assemblages on the upper (450–600 m), middle (650–1500 m) and lower (1600–2200 m) slopes. Although seasonal changes in species abundance and composition were evident, no significant variations in the assemblage structure were observed between the two time periods. Two main trophic pathways involving deep-sea cephalopods were apparent: species mainly linked to benthic resources and species mostly connected to the pelagic food web through active swimming and frequent vertical migrations. Accordingly, two environmental variables best explained the observed patterns: net primary production and river discharge. Phytoplankton availability controls the increase of zooplankton that influences the distribution and abundance of pelagic cephalopods. River discharge affects, in some instances with delays, transfer of organic matter to the benthic trophic pathway and thus to bottom-dwelling cephalopods.

The distribution of deep-water (150–4850 m) benthic and bentho–pelagic cephalopods in the north-east Atlantic is described, based on 592 specimens collected from commercial and research trawling. Thirty-six different species of cephalopod belonging to 14 families were identified, though problems remain with the taxonomy of some of the octopod genera. At the shallower depths (150–500 m) sepiolids were the most abundant group with five species identified. Sepiola atlantica, Sepietta oweniana and Rondeletiola minor were restricted to the shallow depths (<300 m), but Neorossia caroli (400–1535 m) and Rossia macrosoma (205–515 m) extended into deeper water. The squids Todaropsis eblanae and Loligo forbesi were also common in shallow areas (<250 m). Among the incirrate octopods, Eledone cirrhosa was found at depths of 208–490 m. Three putative species of Benthoctopus and two of Bathypolypus were identified occupying depths of 250–2700 m. Graneledoneverrucosa was caught at depths of 1785–2095 m. Cirrate octopods dominated the cephalopod catch from the deeper areas, with Opisthoteuthis massyae occurring from 877 to 1398 m, O. grimaldii from 2165 to 2287 m, Stauroteuthissyrtensis from 1425 to 3100 m, Cirroteuthismuelleri from 700 to 4854 m, Cirrothauma murrayi from 2430 to 4850 m and Grimpoteuthis (five putative species) from 1775 to 4877 m. Abundance estimates of the more frequently caught species were calculated from swept areas of trawls and sledges in the Porcupine Seabight and on the Porcupine Abyssal Plain.

The stomach contents of 221 sperm whales were examined at the Icelandic whaling station between 1977 and 1981. Evidence of at least eight species of fish and 22 species of cephalopod was found, together with an assortment of foreign bodies including rock fragments and fishing nets. Fish remains were found in 87% and cephalopods in 68% of the sperm whale stomachs in this area, but quantification of dietary input is complicated by differential rates of digestion and variation in the retention of indigestible remains in the stomach. Prey species are benthic or pelagic in habit and are caught by the whale in waters from 400 m to at least 1200 m in depth. One fish, the lumpsucker Cyclopterus lumpus, forms a major part of the diet. Ninety-four per cent of cephalopods are oceanic and neutrally buoyant and 84 % of these are ammoniacal. Cranchiids contribute 57% by number and an estimated 25% of the weight, and histioteuthids 26% by number and 38 % of the weight of cephalopods eaten. Three species offish and two of cephalopod have not been previously recorded in sperm whale diets. Comparison with an earlier study shows that the diet is essentially stable over a 14-year period.

AbstractThe diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined during 2003, 2005 and 2010. The diet of sub-adult toothfish was similar to adult toothfish, comprising mainly benthic fishes and cephalopods. Sub-adult toothfish ate a greater variety of smaller prey than adults, including smaller fish and prawns. Grenadiers (Macrourus spp.) were the most important fish and overall prey species. On the continental slope, icefish (Channichthyidae) and eel cods (Muraenolepididae) were also important fish prey, while Psychroteuthis glacialis was the most important cephalopod prey. On oceanic features, toothfish fed mainly on Macrourus spp. but also fed on Antimora rostrata, cephalopods and the occasional mesopelagic to epipelagic fish. Diet varied significantly with toothfish size and location on northern parts of the Mawson and Iselin banks of the Ross Sea continental slope. There was no significant temporal change in diet composition.

Cephalopods are often celebrated as masters of camouflage, but their exploitation of the soft-sediment habitats that dominate the ocean floor has demanded other anti-predator strategies. Previous research has identified a small number of cephalopods capable of burying into sand and mud, but the need to directly access the water column for respiration has restricted them to superficial burying. Here, we report on the first known sub-surface burrowing in the cephalopods, byOctopus kaurna, a small benthic species that uses advanced sand-fluidisation and adhesive mucus for sediment manipulation. This burrowing strategy appears linked to easily fluidised sediments as shown in experimental trials in three size-grades of sediment. While the selective pressures that drove evolution of this behaviour are unknown, its identification enriches our understanding of the possible life-history traits and functional role of mucus in other benthic octopus species living in soft-sediment environments.

Elasmobranch predation has important effects on marine ecosystems. Identifying the main correlates of the feeding habits of skates is of paramount importance for determining their ecological role. We tested the hypotheses that the diet of the spotback skate, Atlantoraja castelnaui, off Uruguay and northern Argentina, changes with increasing body size, between seasons and regions and that prey size increased with predator’s size using a multiple-hypothesis modelling approach. A. castelnaui preyed mainly on teleosts, followed by cephalopods, elasmobranchs and decapods. Small individuals of A. castelnaui consumed decapods and large individuals ate elasmobranchs and cephalopods. The consumption of teleosts was constant along the ontogeny but differed between seasons; more demersal-benthic teleosts were consumed in the cold season, whereas more benthic teleosts were eaten in the warm season. Also, A. castelnaui consumed more cephalopods in the warm season than in the cold season. Benthic teleosts were consumed more in the south region, whereas decapods were eaten more in the north region. A. castelnaui is able to consume larger teleosts as it grows. We conclude that A. castelnaui is a versatile, mainly piscivorous, consumer that shifts its diet with increasing body size and in response to seasonal and regional changes in prey abundance or distribution.

Molluscan assemblages of circalittoral and bathyal soft bottoms of the northern Alboran Sea were studied using an experimental otter trawl. Samples of fauna were collected from 190 hauls during four MEDITS surveys carried out in spring between 2012 and 2015 at depths ranging from 30 to 800 m. Measurements of water column variables (temperature and salinity) and sediment samples were taken in the same locations where faunistic sampling was carried out. A total of 101 species grouped in 55 families were recorded. Cephalopods were the most abundant group, with Abralia veranyi dominating in abundance, Octopus vulgaris in biomass and Illex coindetii and Todarodes sagittatus being the most frequently collected species. Multivariate analyses carried out separately with abundance data of demersal species, benthic species, bivalves, gastropods and cephalopods as well as of all molluscs, generally resulted in three main molluscan assemblages corresponding to a shelf assemblage (30-200 m depth), an upper slope assemblage (201-350 m depth), and a middle slope assemblage (351-800 m depth). PERMANOVA test revealed that significant differences of different groups of molluscs in relation to depth were more acute than to geographical sectors of the Alboran Sea (eastern, central, eastern and insular sectors). Abundance, biomass and species richness decreased with depth with a clear dominance of cephalopods in the slope. Significant geographical differences were mainly detected for demersal and benthic species as well as for gastropods and cephalopods between the insular sector (Alboran Island) and the western and eastern continental sectors. Both depth and temperature were the most influencing variables in the different CCA analyses using datasets of molluscs with different life styles and from different classes, but sedimentological variables displayed a more acute significant relationship with the benthic molluscs than with the demersal ones.

Many cephalopods can rapidly change their external appearance to produce multiple body patterns. Body patterns are composed of various components, which can include colouration, bioluminescence, skin texture, posture, and locomotion. Shallow water benthic cephalopods are renowned for their diverse and complex body pattern repertoires, which have been attributed to the complexity of their habitat. Comparatively little is known about the body pattern repertoires of open ocean cephalopods. Here we create an ethogram of body patterns for the pelagic squid, Dosidicus gigas. We used video recordings of squid made in situ via remotely operated vehicles (ROV) to identify body pattern components and to determine the occurrence and duration of these components. We identified 29 chromatic, 15 postural and 6 locomotory components for D. gigas, a repertoire rivalling nearshore cephalopods for diversity. We discuss the possible functional roles of the recorded body patterns in the behavioural ecology of this open ocean species.

In Tasmanian waters, Arctocephalus pusillus doriferus preyed on 11 species of cephalopods, predominantly Nototodarus gouldi followed by Sepioteuthis australis and Sepia apama. Cephalopods were more important in the diet of the seals in Bass Strait than in southern Tasmanian waters. The species composition in the diet of the seals in these two areas also differed, with the seals in Bass Strait eating mainly N. gouldi, whereas the seals in southern waters fed on benthic octopods. The seals preyed on mainly adult cephalopods over the continental shelf. The size range and species composition of the diet varied according to the sample types, with faeces containing only small beaks relative to regurgitates and stomachs. Errors associated with sample types and application of regression equations are discussed.

Geographic range is an important macroevolutionary parameter frequently considered in paleontological studies as species’ distributions and range sizes are determined by a variety of biotic and abiotic factors well known to affect the differential birth and death of species. Thus, considering how distributions and range sizes fluctuate over time can provide important insight into evolutionary dynamics. This study uses Geographic Information Systems (GIS) and analyses of evolutionary rates to examine how in some species within the Cephalopoda, an important pelagic clade, geographic range size and rates of speciation and extinction changed throughout the Pennsylvanian and early Permian in the North American Midcontinent Sea. This period is particularly interesting for biogeographic and evolutionary studies because it is characterized by repetitive interglacial-glacial cycles, a global transition from an icehouse to a greenhouse climate during the Late Paleozoic Ice Age, and decelerated macroevolutionary dynamics, i.e. low speciation and extinction rates. The analyses presented herein indicate that cephalopod species diversity was not completely static and actually fluctuated throughout the Pennsylvanian and early Permian, matching findings from other studies. However, contrary to some other studies, the mean geographic ranges of cephalopod species did not change significantly through time, despite numerous climate oscillations; further, geographic range size did not correlate with rates of speciation and extinction. These results suggest that pelagic organisms may have responded differently to late Paleozoic climate changes than benthic organisms, although additional consideration of this issue is needed. Finally, these results indicate that, at least in the case of cephalopods, macroevolution during the late Paleozoic was more dynamic than previously characterized, and patterns may have varied across different clades during this interval.

The dicyemid mesozoans (Dicyemida Van Beneden 1882) are a poorly-understood group of marine organisms that are found with high intensities in the renal appendages of benthic cephalopods. The majority of the research focusing on this group is from the northern hemisphere, with very few studies examining the dicyemid fauna of southern hemisphere cephalopod species. Confusion also exists in the literature on the validity of certain families, genera and species within this phylum, and the phylogenetic framework for the dicyemids is scarce. The few studies that have examined dicyemid molecular genetics focus only on single taxon or sole aspects of genome organisation. Furthermore, key parts of the life cycle of dicyemid parasites are unresolved and their position in the Tree of Life is uncertain. My thesis highlights the taxonomic confusion in the literature that surrounds the Dicyemida, and presents a comprehensive list of all dicyemid species currently described to date (Chapter 2). Ten cephalopods species from Australian waters were collected and examined for dicyemids parasites, resulting in new dicyemid species descriptions (Chapters 3, 4 and 5). Host eggs and filtered seawater samples were collected from the cuttlefish mass breeding aggregation at Upper Spencer Gulf, South Australia, Australia, to assess the unknown host life cycle stage where new infection by the dispersive dicyemid embryo occurs. No dicyemid DNA was detected in any host egg or environmental samples, suggesting new infection occurs after the host embryo hatches rather than at the egg stage (Chapter 6). Patterns of infections, prevalence, species richness, co-infection and co-occurrence of dicyemids among infected cephalopods species were explored (Chapter 7). Host size in general did not influence patterns of infection, however where dicyemid species co-occurred, restriction to discrete host sizes was observed, suggesting competition between species may be an important factor leading to niche separation. Calotte shape was found to vary between dicyemid species that co-occurred within a single host individual. Additionally, dicyemid fauna composition was found to vary with host geographical collection locality, alluding to the potential use of dicyemid parasites as biological tags (Chapter 7). The complete cytochrome c oxidase subunit I (COI) minicircle molecule, including the COI gene plus a non-coding region, was sequenced from nine dicyemid species, and comparisons in sequence composition and size were made between and within species (Chapter 8). The first phylogeny of dicyemids including multiple taxa from the two genera that combined contain over 90% of the nominal described species was estimated from Bayesian inference and maximum likelihood analyses. Monotypic species clades were observed, however the paraphyly to the genera suggests classification based on morphological traits may need revision (Chapter 8). The hypothesis that parasite genetics of infected cephalopods will allow for a deeper insight into population structuring compared to that gained with complementary methods was tested, with dicyemid mesozoans infecting giant Australian cuttlefish (Sepia apama) as the chosen system (Chapter 9). The population structure of S. apama previously inferred from host morphology, behaviour and genetics was supported from dicyemid parasite mitochondrial haplotype phylogeography, with an analysis of molecular variance (AMOVA) providing an alternative insight into structuring of this cuttlefish species. This result suggests that in the future, a holistic approach that incorporates parasite and host data (morphology and genetics) should be used to assess cephalopod population boundaries. An invited review article on the use of parasites as biological tags to assess the population structure of marine organisms is presented as the final data chapter (Chapter 10). Comments are made on the guidelines for selecting a parasite species as a reliable tag candidate, the need to incorporate parasite genetic information and the benefits of a multidisciplinary approach. The direct outcomes of my study include the description of the first dicyemid species from Australian waters, insights into the unknowns in the dicyemid life cycle, presentation of the first dicyemid phylogeny allowing taxa classification to be assessed outside of the sole morphological approach and analysis of the use of dicyemid parasites as biological tags, supporting the integration of dicyemid parasite genetics alongside other complementary methods to assess cephalopod population structure. In summary, my study has significantly contributed to the field of dicyemid research, increasing both fundamental and applied knowledge on this enigmatic group of organisms.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2014

The adaptive nature of egg size and juvenile types is of fundamental interest to the life history theory of benthic marine invertebrates. One tenet of life history theory for these organisms predicts that the evolution and maintenance of dichotomous reproductive strategies is a fecundity-survival trade-off and environmental factors strongly influence the evolutionary history of these strategies. In this thesis I aimed to examine the evolutionary relationships among the benthic shallow-water octopuses (subfamily Octopodinae) using a molecular phylogenetic approach. The best phylogenetic hypothesis was then used in a comparative phylogenetic analysis to examine the evolutionary history of reproductive strategies. I was interested in examining whether evolutionary transitions in egg size have been influenced by macro-environmental variation during their evolutionary history. A molecular phylogenetic analysis was used to reconstruct a broad-scale phylogeny of the benthic shallow-water octopuses from the amino acid sequences of two mitochondrial DNA genes: Cytochrome oxidase subunit III and Cytochrome b apoenzyme and, the nuclear DNA gene, Elongation Factor-1α. Maximum Likelihood and Bayesian approaches were implemented to estimate the phylogeny and non-parametric bootstrap was used to verify confidence intervals for Bayesian topologies. Overall the genes used in this study were better suited to the examination of recent phylogenetic relationships, which has helped to resolve the relationships among closely related taxa, rather than deeper divergences among genera and species groups. The phylogenies revealed strong evidence that the genus Octopus is not a monophyletic group. Interestingly, a number of monophyletic sub-groups comprising closely related terminal taxa exist within the genus. Based on these findings it is clear that the systematics of the subfamily Octopodinae requires major revision. Deep relationships within this group remain only partially resolved and to improve resolution among distantly related species sequence data from conserved genes should be examined. The dichotomous reproductive strategies that exist among species of the benthic shallow-water octopuses are an exceptional life history feature as they are only one of two groups within the Cephalopoda that maintain such a dichotomy. The reconstructed pattern of evolution in inferred juvenile types showed that the planktonic juvenile type was ancestral among 22 species and three independent evolutionary transitions to the benthic juvenile type were observed with no subsequent reversals among taxa. The comparative phylogenetic analysis revealed that egg size covaries with variation in latitudinal gradient and more weakly with body size. These findings suggest that, evolutionarily, egg size is an adaptive trait that responds to a number of selection pressures including those associated with macro-environmental variation. Based on these results it is suggested that the dichotomy in egg sizes may be maintained by a fecundity-survival trade-off that responds to natural selection associated with the environmental conditions that a species inhabits. Under the assumption that egg size and juvenile type are tightly correlated traits I propose a number of hypotheses regarding the evolution of reproductive strategies in octopuses. Small eggs and planktonic juvenile types are likely to be the ancestral states for shallow-water octopuses in general. Based on the covariation of egg size with latitudinal variation, inter-specific evolution in both egg size and juvenile type is likely to reflect adaptations to natural selection resulting from large-scale ecological factors; a finding that is consistent with benthic marine invertebrate life history theory. Large eggs and benthic juveniles may be an adaptation to high-risk conditions such as deep-sea and/or cold environments as supported by the tendency for transitions in reproductive strategy to occur most frequently in the direction of small egg size - planktonic juvenile type to large egg - benthic juvenile type. Evidence that egg sizes are constrained by phylogeny was observed, which may also indicate a constraint on reproductive strategies such that transitions in strategy are rare. The dichotomous reproductive strategies that exist among species of the benthic shallow-water octopuses are an exceptional life history feature that is only observed in one other cephalopod family, the Idiosepiidae. Many other benthic marine invertebrates also maintain dual reproductive strategies between species and a large body of theory exists regarding how these traits have evolved and been maintained throughout evolutionary history. Using a comparative phylogenetic approach it was possible to investigate hypotheses generated by optimality models and experimental observations in an historical context and to examine the patterns of evolution in traits.

The adaptive nature of egg size and juvenile types is of fundamental interest to the life history theory of benthic marine invertebrates. One tenet of life history theory for these organisms predicts that the evolution and maintenance of dichotomous reproductive strategies is a fecundity-survival trade-off and environmental factors strongly influence the evolutionary history of these strategies. In this thesis I aimed to examine the evolutionary relationships among the benthic shallow-water octopuses (subfamily Octopodinae) using a molecular phylogenetic approach. The best phylogenetic hypothesis was then used in a comparative phylogenetic analysis to examine the evolutionary history of reproductive strategies. I was interested in examining whether evolutionary transitions in egg size have been influenced by macro-environmental variation during their evolutionary history. A molecular phylogenetic analysis was used to reconstruct a broad-scale phylogeny of the benthic shallow-water octopuses from the amino acid sequences of two mitochondrial DNA genes: Cytochrome oxidase subunit III and Cytochrome b apoenzyme and, the nuclear DNA gene, Elongation Factor-1α. Maximum Likelihood and Bayesian approaches were implemented to estimate the phylogeny and non-parametric bootstrap was used to verify confidence intervals for Bayesian topologies. Overall the genes used in this study were better suited to the examination of recent phylogenetic relationships, which has helped to resolve the relationships among closely related taxa, rather than deeper divergences among genera and species groups. The phylogenies revealed strong evidence that the genus Octopus is not a monophyletic group. Interestingly, a number of monophyletic sub-groups comprising closely related terminal taxa exist within the genus. Based on these findings it is clear that the systematics of the subfamily Octopodinae requires major revision. Deep relationships within this group remain only partially resolved and to improve resolution among distantly related species sequence data from conserved genes should be examined. The dichotomous reproductive strategies that exist among species of the benthic shallow-water octopuses are an exceptional life history feature as they are only one of two groups within the Cephalopoda that maintain such a dichotomy. The reconstructed pattern of evolution in inferred juvenile types showed that the planktonic juvenile type was ancestral among 22 species and three independent evolutionary transitions to the benthic juvenile type were observed with no subsequent reversals among taxa. The comparative phylogenetic analysis revealed that egg size covaries with variation in latitudinal gradient and more weakly with body size. These findings suggest that, evolutionarily, egg size is an adaptive trait that responds to a number of selection pressures including those associated with macro-environmental variation. Based on these results it is suggested that the dichotomy in egg sizes may be maintained by a fecundity-survival trade-off that responds to natural selection associated with the environmental conditions that a species inhabits. Under the assumption that egg size and juvenile type are tightly correlated traits I propose a number of hypotheses regarding the evolution of reproductive strategies in octopuses. Small eggs and planktonic juvenile types are likely to be the ancestral states for shallow-water octopuses in general. Based on the covariation of egg size with latitudinal variation, inter-specific evolution in both egg size and juvenile type is likely to reflect adaptations to natural selection resulting from large-scale ecological factors; a finding that is consistent with benthic marine invertebrate life history theory. Large eggs and benthic juveniles may be an adaptation to high-risk conditions such as deep-sea and/or cold environments as supported by the tendency for transitions in reproductive strategy to occur most frequently in the direction of small egg size - planktonic juvenile type to large egg - benthic juvenile type. Evidence that egg sizes are constrained by phylogeny was observed, which may also indicate a constraint on reproductive strategies such that transitions in strategy are rare. The dichotomous reproductive strategies that exist among species of the benthic shallow-water octopuses are an exceptional life history feature that is only observed in one other cephalopod family, the Idiosepiidae. Many other benthic marine invertebrates also maintain dual reproductive strategies between species and a large body of theory exists regarding how these traits have evolved and been maintained throughout evolutionary history. Using a comparative phylogenetic approach it was possible to investigate hypotheses generated by optimality models and experimental observations in an historical context and to examine the patterns of evolution in traits.

<em>Abstract.</em>—The abyssal grenadier <em>Coryphaenoides armatus </em>(Hector 1875), family Macrouridae, is a benthopelagic deep-sea species with a depth range of 282–5,180 m, with most observations and captures at depths of 2,500 m and deeper. It is one of the most abundant grenadier species in the world’s oceans but is absent from the Mediterranean Sea, Arctic Ocean, Indian Ocean north of 45°S, and has not yet been recorded from the Southern Ocean south of the Antarctic Polar Front. Typical total lengths range from 20 to 80 cm and the maximum recorded is 102 cm. Dietary items include mesopelagic fishes and cephalopods, and benthic items such as crustaceans and bivalves. The abyssal grenadier is well documented as an opportunistic scavenger and this propensity has been used to attract individuals to bait within view of submersibles and underwater camera systems to make <em>in situ </em>observations of behavior. Baited cameras have been in use to observe deep-sea scavengers since the late 1960s, with the first confirmed observation of the abyssal grenadier in 1971. More recently, baited photographic autonomous landers have been used to gain data on respiration rates, size frequency, and swimming velocity. In addition, models have been developed and refined to estimate local densities and to quantify the number of fish present at a food fall and their staying time at bait. This ultimately means that baited-camera-derived abundance estimates can be produced, and that the numbers of scavenging grenadiers and how long they remain at a small food fall can be linked to the productivity of the overlying surface waters.

<em>Abstract.</em>—The abyssal grenadier <em>Coryphaenoides armatus </em>(Hector 1875), family Macrouridae, is a benthopelagic deep-sea species with a depth range of 282–5,180 m, with most observations and captures at depths of 2,500 m and deeper. It is one of the most abundant grenadier species in the world’s oceans but is absent from the Mediterranean Sea, Arctic Ocean, Indian Ocean north of 45°S, and has not yet been recorded from the Southern Ocean south of the Antarctic Polar Front. Typical total lengths range from 20 to 80 cm and the maximum recorded is 102 cm. Dietary items include mesopelagic fishes and cephalopods, and benthic items such as crustaceans and bivalves. The abyssal grenadier is well documented as an opportunistic scavenger and this propensity has been used to attract individuals to bait within view of submersibles and underwater camera systems to make <em>in situ </em>observations of behavior. Baited cameras have been in use to observe deep-sea scavengers since the late 1960s, with the first confirmed observation of the abyssal grenadier in 1971. More recently, baited photographic autonomous landers have been used to gain data on respiration rates, size frequency, and swimming velocity. In addition, models have been developed and refined to estimate local densities and to quantify the number of fish present at a food fall and their staying time at bait. This ultimately means that baited-camera-derived abundance estimates can be produced, and that the numbers of scavenging grenadiers and how long they remain at a small food fall can be linked to the productivity of the overlying surface waters.