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One of the most remarkable groups of deep-sea squids is the Magnapinnidae, known for their large fins and strikingly long arm and tentacle filaments. Little is known of their biology and ecology as most specimens are damaged and juvenile, and in-situ sightings are sparse, numbering around a dozen globally. As part of a recent large-scale research programme in the Great Australian Bight, Remotely Operated Vehicles and a towed camera system were deployed in depths of 946-3258 m resulting in five Magnapinna sp. sightings. These represent the first records of Bigfin Squid in Australian waters, and more than double the known records from the southern hemisphere, bolstering a hypothesis of cosmopolitan distribution. As most previous observations have been of single Magnapinna squid these multiple sightings have been quite revealing, being found in close spatial and temporal proximity of each other. Morphological differences indicate each sighting is of an individual rather than multiple sightings of the same squid. In terms of morphology, previous in-situ measurements have been roughly based on nearby objects of known size, but this study used paired lasers visible on the body of a Magnapinna squid, providing a more accurate scaling of size. Squid of a juvenile size were also recorded and are confirmed to possess the long distal filaments which have thus far been mostly missing from specimens due to damage. We have described fine-scale habitat, in-situ colouration, and behavioural components including a horizontal example of the 'elbow' pose, and coiling of distal filaments: a behaviour not previously seen in squid. These sightings add to our knowledge of this elusive and intriguing genus, and reinforce the value of imagery as a tool in deep-sea squid research.

Data from the fishery of S. oualaniensis in the northern Indian Ocean from January to March and October to December 2017 to 2019 were modeled with sea surface temperature (SST), wind speed (WS), and photosynthetically active radiation (PAR). In this study, the fishing effort was used to evaluate the suitability index (SI) at SST, WS, and PAR. An integrated habitat suitability model (HSI) was developed with different weighting scenarios and weighting schemes. The optimal case was selected by calculation and comparison with the proportion of catch, effort, and catch per unit effort (CPUE) in the HSI interval (0~0.2, 0.2~0.6, 0.6~1); validation was performed using data from 2019. The weight of the optimal HSI model was 0.25 for sea surface temperature and photosynthetically active radiation, and 0.5 for wind speed. This model yielded the best performance and could accurately predict the fishing ground of S. oualaniensis in the northern Indian Ocean. The findings suggest that the integrated HSI model can predict the distribution of S. oualaniensis commendably, with wind speed as the most important factor affecting the spatial distribution of S. oualaniensis’ habitat in the northern Indian Ocean. By analyzing habitat selection by S. oualaniensis, this study verified and predicted the distribution of squid in the northern Indian Ocean, which allows the distribution of squid resources and fishing grounds to be modeled, and for the sustainable use of squid fishery resources.

The growing applications of tissue engineering technologies warrant the search and development of biocompatible materials with an appropriate strength and elastic moduli. Here, we have extensively studied a collagenous membrane (GSCM) separated from the mantle of the Giant squid Dosidicus Gigas in order to test its potential applicability in regenerative medicine. To establish the composition and structure of the studied material, we analyzed the GSCM by a variety of techniques, including amino acid analysis, SDS-PAGE, and FTIR. It has been shown that collagen is a main component of the GSCM. The morphology study by different microscopic techniques from nano- to microscale revealed a peculiar packing of collagen fibers forming laminae oriented at 60–90 degrees in respect to each other, which, in turn, formed layers with the thickness of several microns (a basketweave motif). The macro- and micromechanical studies showed high values of the Young’s modulus and tensile strength. No significant cytotoxicity of the studied material was found by the cytotoxicity assay. Thus, the GSCM consists of a reinforced collagen network, has high mechanical characteristics, and is non-toxic, which makes it a good candidate for the creation of a scaffold material for tissue engineering.

Squid are characterized by flexible life-history traits (LHTs) that change in response to changing oceanic parameters. Male alternative reproductive tactics (ARTs), characterized by large-sized ‘consorts’ versus small-sized ‘sneakers’, are commonly observed in loliginid species. This study reports on LHTs flexibility in male squids displaying ARTs. LHTs of consorts and sneakers in Uroteuthis edulis, including body size, age, growth rate and gonado-somatic energy allocation, were compared among seasonal and geographical groups from Japan and Taiwan. The ratio of consorts to sneakers was highest in the group spawning in the ‘Japan-warm’ season (June–November), followed by that of the ‘Japan-cold’ season (December–May), and lowest in Taiwan (spring and autumn). LHTs were compared among cohorts separated by hatching season and catch location (Jwarm, Jcold and Taiwan cohorts). Mean body size of consorts showed no difference among cohorts, although Taiwan consorts were relatively younger than Japan consorts. Mean size and age of sneakers decreased with increased water temperature at hatching. Growth rates of consorts and sneakers were slightly different among cohorts, in accordance with differences of statolith increment widths during their early life stage (50–150 days). Growth rates of both consorts and sneakers were highest in the Taiwan cohort, followed by the Jwarm cohort, with the Jcold cohort lowest. Sneakers invested more both in mantle and gonadal weights than consorts in all cohorts. Gonado-somatic energy allocation patterns of consorts and sneakers were consistent at different temperatures. LHTs of U. edulis consorts and sneakers were strongly influenced by temperature, with higher flexibility in sneakers than consorts.

Autoregressive spectral analysis revealed underlying cyclical trends in the highly variable biomass and mean body weight indices of two Northwest Atlantic squid species with opposing life histories. Doryteuthis pealeii attaches its egg masses to the seabed in shallow waters on the Northeast USA shelf. The broader-ranging Illex illecebrosus uses the Gulf Stream (GS) to transport its pelagic egg masses and paralarvae from the Southern (USA shelf) to the Middle (Scotian Shelf) and Northern (Grand Banks) Fishery Regions. We compared significant spectral peaks, or cycles, between the 1993–2016 survey indices, GS latitudinal positions (at 74°, 70°, 65°, 60°, 55° and 50°W) and winter North Atlantic Oscillation (NAO) indices to reveal any synchronicities. Positive NAO anomalies associated with northward GS position shifts were predominant. NAO indices exhibited 2–3-year, 4–5-year, and near-decadal cycles. GS position periodicities included 2–3-year, 3–4-year, and both timescales for west of 65°W (Western Segment), east of 60°W (Eastern), and from 65° to 60°W, respectively. I. illecebrosus indices exhibited stock-wide 3–4-year cycles and 2–3-year cycles for the Middle and Southern Fishery Regions that were synchronous with GS latitudinal positions for the Eastern and Western GS Segments, respectively. D. pealeii biomass cycles varied seasonally. Spring 4–5-year cycles were synchronous with the NAO, and fall near-decadal cycles were synchronous with the NAO and all GS locations analyzed. Our findings of inter-annual biomass and body weight cycles from 2 to 3 years to near-decadal are remarkable given the sub-annual lifespans of both species, but confirm the tight coupling between recruitment, body size, and cyclical environmental forcing factors.

Trophic interactions in the Antarctic Ocean are likely to be affected by changing environmental conditions. Some of these impacts can be observed, and predicted, by monitoring trace element concentrations in the tissues of animals at certain trophic levels. The ‘glacial’ squid (Psychroteuthis glacialis) is an ideal indicator species for measuring trace element bioaccumulation in the Ross Sea because it plays a central role in local marine food webs. Trace elements (Al, As, Cd, Co, Cu, Fe, Hg, Ni, Mn, Pb, U, V, and Zn) were measured in mantle and digestive gland tissues of 57 P. glacialis specimens, including juvenile and mature individuals. Significant differences in Al, As, Cd, Cu, Fe, Mn, V, and Zn concentrations were observed across life stages, with juveniles generally having the highest concentrations. As the bioaccumulation of most trace elements is influenced by diet, our results suggest different feeding patterns between juvenile and mature P. glacialis. In turn, it is likely that the life stage of P. glacialis individuals consumed by predators will determine trace element exposure higher up the trophic web. Overall, this Antarctic squid appears to be influenced by the trace element cycling in the Ross Sea and contains lower concentrations of trace elements than have been observed in squids in warmer waters.