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The oegopsid squid family Onychoteuthidae was recently revised based on morphology, but sufficient material for a complementary molecular analysis has not been available until now. In the present study, over 250 sequences of cytochrome c oxidase subunit I (COI) and 16S rRNA for 222 individuals were analysed to create a combined phylogeny for the family. Results support monophyly for the family and all seven onychoteuthid genera (including Moroteuthopsis, established herein as the senior genus name for species formerly attributed to Kondakovia); 29 genetically distinct species were recovered, with the BIN (Barcode Index Number) analysis for COI showing good congruence overall with morphological species groupings. No sequences were available for five additional known species, making the total family diversity likely to exceed 34 species. Seven of the BINs formed in this study appear to represent undescribed taxa, suggesting that even in this relatively well-studied family, much additional work remains before a comprehensive understanding of the diversity and evolutionary relationships for the Onychoteuthidae can be achieved., (Copyright © 2018. Published by Elsevier Inc.)

An exhaustive study of existing data on the relationship between egg size and maximum size of embryonic shells in 42 species of extant cephalopods demonstrated that these values are approximately equal regardless of taxonomy and shell morphology. Egg size is also approximately equal to mantle length of hatchlings in 45 cephalopod species with rudimentary shells. Paired data on the size of the initial chamber versus embryonic shell in 235 species of Ammonoidea, 46 Bactritida, 13 Nautilida, 22 Orthocerida, 8 Tarphycerida, 4 Oncocerida, 1 Belemnoidea, 4 Sepiida and 1 Spirulida demonstrated that, although there is a positive relationship between these parameters in some taxa, initial chamber size cannot be used to predict egg size in extinct cephalopods; the size of the embryonic shell may be more appropriate for this task. The evolution of reproductive strategies in cephalopods in the geological past was marked by an increasing significance of small-egged taxa, as is also seen in simultaneously evolving fish taxa., (© 2017 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

Cephalopods are a relatively small class of molluscs (~800 species), but they support some large industrial scale fisheries and numerous small-scale, local, artisanal fisheries. For several decades, landings of cephalopods globally have grown against a background of total finfish landings levelling off and then declining. There is now evidence that in recent years, growth in cephalopod landings has declined. The commercially exploited cephalopod species are fast-growing, short-lived ecological opportunists. Annual variability in abundance is strongly influenced by environmental variability, but the underlying causes of the links between environment and population dynamics are poorly understood. Stock assessment models have recently been developed that incorporate environmental processes that drive variability in recruitment, distribution and migration patterns. These models can be expected to improve as more, and better, data are obtained on environmental effects and as techniques for stock identification improve. A key element of future progress will be improved understanding of trophic dynamics at all phases in the cephalopod life cycle. In the meantime, there is no routine stock assessment in many targeted fisheries or in the numerous by-catch fisheries for cephalopods. There is a particular need for a precautionary approach in these cases. Assessment in many fisheries is complicated because cephalopods are ecological opportunists and stocks appear to have benefited from the reduction of key predator by overexploitation. Because of the complexities involved, ecosystem-based fisheries management integrating social, economic and ecological considerations is desirable for cephalopod fisheries. An ecological approach to management is routine in many fisheries, but to be effective, good scientific understanding of the relationships between the environment, trophic dynamics and population dynamics is essential. Fisheries and the ecosystems they depend on can only be managed by regulating the activities of the fishing industry, and this requires understanding the dynamics of the stocks they exploit., (© 2014 Elsevier Ltd. All rights reserved.)

Global studies imply that cephalopods have benefited from climate change. However, in most areas, species-specific long-term cephalopod data sets do not exist to support this implication and to analyse the response of cephalopods to environmental changes. Our results illustrate that historical studies, in combination with recent data sets, can fill this gap, enabling descriptions of ecological changes over a long time. We show substantial changes in the cephalopod biodiversity of the North Sea at species level over the past 100 years. Some species, which seemed to migrate into the North Sea only for spawning or foraging in the nineteenth century, occur permanently in the North Sea nowadays. This applies, for example, to the loliginids Loligo forbesii and Alloteuthis subulata. The ommastrephids Todaropsis eblanae and Illex coindetii, now constantly present as well, had been described only as accidental migrants 100 years ago. [ABSTRACT FROM AUTHOR]

Published data on initial chamber (protoconch) diameter in 507 species, and embryonic shell (ammonitella) diameter in 231 species of Ammonoidea, and embryonic shell (nauta) diameters for 132 species of coiled Nautiloidea, were used to examine evolutionary change in ectocochleate cephalopod reproductive strategies. Palaeotemperatures were found to be a key factor influencing historical changes in the evolution of egg size in ammonoids and nautiloids. A negative relationship was found between egg size and warming of the Earth's climate. Factors related to habitat were also important; in general egg size was larger in cold-water cephalopods. Egg size in Lytoceratina and Phylloceratina in the deep waters of the upper continental slope was much larger than in epipelagic Scaphitidae, as in modern fish and squids. Small eggs and high evolutionary rates helped ammonoids to colonise new habitats and develop high biological diversity, but involved them in planktonic food webs making them more vulnerable to abiotic variability (e.g., climatic changes), ultimately leading to their extinction. Large eggs helped nautiloids to persist through geological history, but at the cost of lower biological diversity, lower evolutionary rates and restricted options for colonising new habitats. Large-egged species such as nautiloids are more vulnerable to ecological, biotic disasters such as the appearance of new predators, including modern fishery. Independence from the planktonic food web is likely to be very important for a taxon's long-term survival over evolutionary history, as demonstrated also by Coelacanthiformes and Elasmobranchia. [ABSTRACT FROM AUTHOR]

Diet of bluenose warehou, Hyperoglyphe antarctica , was investigated from samples collected during commercial fishing (trawling and longlining) on seamounts in the Tristan da Cunha EEZ in the South Atlantic Ocean. Bluenose warehou (57–123 cm TL, N = 309) was found to forage on a broad range of prey, dominated by mesopelagic cephalopods (squid families Onychoteuthidae and Histioteuthidae, Pholidoteuthis massyae and octopus Haliphron atlanticus), Thaliacea (salps and pyrosomes) and a sternoptychid Maurolicus inventionis. Bluenose warehou exhibited a range of foraging strategies from browsing on dense aggregations of passively drifting jelly-like zooplankton to catching mobile nektonic fish. Bluenose also consumed body parts of the gelatinous giant octopus H. atlanticus , which may have been scavenged or predated. The study indicates that bluenose warehou has an unusually broad prey range for a teleost. The diversity of prey and high flexibility of the hunting strategies permitted the bluenose warehou to prosper in the highly changeable and dynamic environments of underwater seamounts. • Bluenose warehou Hyperoglyphe antarctica has an unusually broad prey range for a teleost. • Fish might browse on passively drifting jelly-like zooplankton or catch mobile nektonic fish. • During ontogeny the warehou gradually moves from browsing to hunting strategy. • Flexibility of the hunting strategies helps this fish to prosper in dynamic environments of seamounts. [ABSTRACT FROM AUTHOR]

The article reports a sighting of penis enlargement in a deep-water squid. The study involves a mature moribund male of the greater hooked squid which was count on the Patagonian slope south of the Falkland Islands. According to the authors, during the maturity assessment for which the mantle of the squid was opened, the penis of the squid suddenly started to erect. It notes that several spermatophores were ejaculated from the penis tip following the elongation.

Cephalopods are a relatively small class of molluscs (~ 800 species), but they support some large industrial scale fisheries and numerous small-scale, local, artisanal fisheries. For several decades, landings of cephalopods globally have grown against a background of total finfish landings levelling off and then declining. There is now evidence that in recent years, growth in cephalopod landings has declined. The commercially exploited cephalopod species are fast-growing, short-lived ecological opportunists. Annual variability in abundance is strongly influenced by environmental variability, but the underlying causes of the links between environment and population dynamics are poorly understood. Stock assessment models have recently been developed that incorporate environmental processes that drive variability in recruitment, distribution and migration patterns. These models can be expected to improve as more, and better, data are obtained on environmental effects and as techniques for stock identification improve. A key element of future progress will be improved understanding of trophic dynamics at all phases in the cephalopod life cycle. In the meantime, there is no routine stock assessment in many targeted fisheries or in the numerous by-catch fisheries for cephalopods. There is a particular need for a precautionary approach in these cases. Assessment in many fisheries is complicated because cephalopods are ecological opportunists and stocks appear to have benefited from the reduction of key predator by overexploitation. Because of the complexities involved, ecosystem-based fisheries management integrating social, economic and ecological considerations is desirable for cephalopod fisheries. An ecological approach to management is routine in many fisheries, but to be effective, good scientific understanding of the relationships between the environment, trophic dynamics and population dynamics is essential. Fisheries and the ecosystems they depend on can only be managed by regulating the activities of the fishing industry, and this requires understanding the dynamics of the stocks they exploit. [ABSTRACT FROM AUTHOR]