Abstract: Jennifer Mather has nicely summarized what is known about consciousness in shallow water octopods as well as what is known about shallow water squids and cuttlefish. However, once she gets below SCUBA depths, she misses out on most of cephalopod diversity. I have attempted to add this aspect and perhaps some evolutionary biology to this target article.

Stable isotope analysis of museum specimens presents an opportunity to evaluate trophic relationships from historical surveys. After testing the effects of preservation methods on archived specimens, we analyzed beak tissue from 69 Northern shortfin squid (Illex illecebrosus) collected between 1873 and 1987 from the Northeast U.S. Continental Shelf Large Marine Ecosystem. Stable nitrogen (δ15N) and carbon (δ13C) isotopes were used to infer ecological changes in I. illecebrosus across historical periods spanning the pre-industrial era (late 1800s), subsequent periods of industrial fishing (1930–1960; 1960–1976), and widespread industry regulation (1985–1995). δ15N values for samples collected in the 1900s were significantly depleted compared to values in the 1800s, with the highest δ15N values occurring between 1985 and 1995. There was also a significant shift over time to more depleted δ13C values. Illex illecebrosus occupied completely distinct isotopic spaces during the pre-industrial (1800s) and industrial (1930–1995) periods, suggesting a change in food-web linkages and habitat use over the last century. Changes in δ15N indicated a shift to lower trophic-level foraging habits in the 1900’s, while shifts in δ13C may be associated with mechanisms such as the Suess effect and increased reliance on more pelagic resources. Isotopic niche breadth and diversity increased in I. illecebrosus over time, potentially indicating expanded resource use associated with anthropogenic impacts on regional trophic guild structure. Our results are the first to examine isotopic changes of I. illecebrosus over multi-decadal periods using museum collections, and among the first to track long-term changes in the trophic role of cephalopods in marine ecosystems.

Phylogenies for Octopoda have, until now, been based on morphological characters or a few genes. Here we provide the complete mitogenomes and the nuclear 18S and 28S ribosomal genes of twenty Octopoda specimens, comprising 18 species of Cirrata and Incirrata, representing 13 genera and all five putative families of Cirrata (Cirroctopodidae, Cirroteuthidae, Grimpoteuthidae, Opisthoteuthidae and Stauroteuthidae) and six families of Incirrata (Amphitretidae, Argonautidae, Bathypolypodidae, Eledonidae, Enteroctopodidae, and Megaleledonidae) which were assembled using genome skimming. Phylogenetic trees were built using Maximum Likelihood and Bayesian Inference with several alignment matrices. All mitochondrial genomes had the 'typical' genome composition and gene order previously reported for octopodiforms, except Bathypolypus ergasticus, which appears to lack ND5, two tRNA genes that flank ND5 and two other tRNA genes. Argonautoidea was revealed as sister to Octopodidae by the mitochondrial protein-coding gene dataset, however, it was recovered as sister to all other incirrate octopods with strong support in an analysis using nuclear rRNA genes. Within Cirrata, our study supports two existing classifications suggesting neither is likely in conflict with the true evolutionary history of the suborder. Genome skimming is useful in the analysis of phylogenetic relationships within Octopoda; inclusion of both mitochondrial and nuclear data may be key.

Abstract Habitat characterization is important to assess fully the niches of different organisms. There is a large knowledge gap regarding habitat use by deep‐sea benthic incirrate octopods, partly due to their assumed preference for hard‐to‐sample rocky substrata. This study uses observations from in situ videos recorded by remotely operated vehicles (ROVs) deployed from the NOAA Ship Okeanos Explorer and implements the Coastal and Marine Ecological Classification Standard (CMECS) to describe the habitat of three common species of bathyal incirrate octopods living in the western North Atlantic Ocean: Bathypolypus bairdii (Verrill 1873), Graneledone verrucosa (Verrill 1881), and Muusoctopus johnsonianus (Allcock, Strugnell, Ruggiero, & Collins 2006). Significant differences in species' preferences for geoform setting, depth, and substrate type were found. All three species are most likely to be observed by ROV in a submarine canyon and least likely to be seen on a seamount. B. bairdii was found shallower than G. verrucosa and M. johnsonianus. This is the first study of its kind using CMECS to classify the habitat of specific organisms as opposed to the habitat types in a specific area.

Oceanic squids of the order Oegopsida are ecologically and economically important members of the pelagic environment. They are the most diverse group of cephalopods, with 24 families that are divergent morphologically. Despite their importance, knowledge of phylogenetic relationships among oegopsids is less than that among neritic cephalopods. Here, we provide the complete mitogenomes and the nuclear 18S and 28S ribosomal genes for 35 selected oceanic squids, which were generated using genome skimming. We performed maximum likelihood and Bayesian inference analyses that included 21 of the 24 oegopsid families. In our analyses, the architeuthid, chiroteuthid and enoploteuthid family groups, which have been proposed previously based on morphological and natural history characteristics, were retrieved as monophyletic. The morphologically divergent Cranchiidae formed a well-supported clade with families Ommastrephidae and Thysanoteuthidae, with a unique mitochondrial gene order. The family Lycoteuthidae was revealed as paraphyletic and contained Pyroteuthidae. Thus, the two lycoteuthid subfamilies are herein elevated to family level, increasing the number of oegopsid squid families to 25. In order to describe the diversity and evolutionary trends of oegopsid squids accurately, the superfamilies Architeuthoidea, Chiroteuthoidea, Cranchioidea and Enoploteuthoidea are resurrected from the literature, and the superfamilies Cycloteuthoidea, Octopoteuthoidea and Pholidoteuthoidea are proposed. The phylogenetic positions of Gonatidae, Histioteuthidae and Onychoteuthidae were not stable in our phylogenetic analyses and are not assigned to a superfamily. This study supports the utility of genome skimming to solve the phylogenetic relationships of oceanic squids.

Only two species of Helicocranchia — Helicocranchia pfefferi Massy, 1907 and Helicocranchia papillata Nesis, 1987—are currently accepted as valid. The genus is found globally in tropical and subtropical regions at depths to >1000 m ( Voss 1980 ). We collected Helicocranchia specimens in the northern Gulf of Mexico during the DEEPEND project (Deep Pelagic Nekton Dynamics of the Gulf of Mexico; sampling 2015–2018) and from the western North Atlantic Ocean during two different research cruises. Physical examination of specimens found differences from recognized species in external pigmentation and in the morphology of the gladius rostrum. Molecular analysis of the COI gene in the specimens also revealed species-level differences. This study reviews current taxonomy and describes a new Helicocranchia species.

The scale of the Deepwater Horizon disaster was and is unprecedented: geographic extent, pollutant amount, countermeasure scope, and of most relevance to this Research Topic issue, range of ecotypes affected. These ecotypes include coastal/nearshore, continental shelf, deep benthic, and open-ocean domains, the last of which is the subject of this synthesis. The open-ocean ecotype comprises ~90% of the volume of the Gulf of Mexico. The exact percentage of this ecotype contaminated with toxins is unknown due to its three-dimensional nature and dynamics, but estimates suggest that the footprint encompassed most of its eastern half. Further, interactions between the water column and the deep benthos may be persistent, making this synthesis one of time (a decade) rather than event conclusion. Here we examine key elements of the open-ocean ecosystem, with emphasis on vulnerability and resilience. Of paramount importance relative to the Gulf nearshore and shelf ecotypes, pre-disaster baseline data were lacking for most of the fauna. In such cases, inferences were drawn from post-disaster assessments. Both phytoplankton and mesozooplankton vulnerabilities were quite high, but resilience appeared equally so. The phytoplankton situation was a bit more complex in that toxin-imposed reductions may have been offset by nutrient injection via high freshwater discharge in 2010. Intermediate trophic levels exhibited population-level depressions, ostensibly due to high vulnerability and low resilience. Apex predator impacts were variable. Certain large epipelagic fishes may have avoided the highest concentrations of hydrocarbons/dispersant, and thus larval abundances returned to pre-disaster levels of variability and abundance within a few years after a steep initial decline. Oceanic cetaceans, particularly shallow-diving stenellid dolphins, did not appear to avoid oiled waters and exhibited strong declines in the northern Gulf. Given that population declines of many open-ocean taxa appear to be ongoing a decade later, we conclude that this largest of Gulf ecosystem components, like its deep-benthic counterpart, is as fragile as it is voluminous. This is particularly concerning given the rapid, and likely irreversible, shift to deeper waters by the US and Mexican oil industries in concert with the higher likelihood of accidents with increasing platform depth.

The ecological role of large thecosome pteropods in the pelagic ecosystem of the northern Gulf of Mexico (GoM) may be substantial, both in the food web and biogeochemical cycling. We analyzed species abundances, vertical and horizontal distributions of large species with calcareous shells (those collected in 3-mm mesh nets). Pteropod samples were collected following the 2010 Deepwater Horizon oil (DWH) spill by two midwater sampling programs: the Offshore Nekton Sampling and Analysis Program (ONSAP 2011) and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND 2015) projects. All samples were collected using a 10-m(2) Multiple Opening/Closing Net and Environmental Sensing System (MOC10) midwater trawl, with 3-mm mesh. This gear sampled five discrete depths between 0-1500 m. Over 13,000 pteropod specimens were examined, with 25 species identified. Clio pyramidata Linnaeus 1767 was the most abundant species during both collection periods. Five genera (Diacria, Clio, Styliola, Cuvierina, Cavolinia) demonstrated diel vertical migration from the mesoto epipelagic zone.

The molluscan clade Decapodiformes (Cephalopoda) comprises a diverse and enigmatic assemblage including inshore and offshore squids, bobtails, cuttlefishes, and the ram's horn squid (Spirulida: Spirula spirula). The latter species is of particular interest to paleontologists because it is the only living cephalopod with an internal chambered, spiral-shaped, calcareous shell resembling those seen in some fossil cephalopod taxa. Spirulida has been difficult to place phylogenetically, in part because it shares different features with sepiolids, sepiids, and oegopsids, creating conflict in morphological analyses. Unlike morphological assumptions of a close relationship with sepiids, previous molecular studies have found support for Spirulida as a close relative of Bathyteuthida and Oegopsida. Identifying the correct phylogenetic placement of Spirulida could allow alternative hypotheses of phragmocone evolution, e.g., retention of an ancestral phragmocone in Spirulida and Sepiida vs. independent reacquisition of the phragmocone in these taxa, to be evaluated. In the present study, we combined new, high-quality transcriptome data for a specimen of Spirula spirula with additional new and previously published transcriptome data for decapodiform cephalopods. Phylogenetic analyses of several matrices yielded trees in which Spirula spirula was recovered as the sister group of the oceanic open-eyed squids (Oegopsida). This close relationship of Spirula to oceanic squids, rather than to nearshore, demersal/benthic decapodiform lineages, provides further support for an "onshore to offshore" model of decapodiform evolution.

During a manned submersible dive in the Philippine Trench, a solitary oegopsid squid of the monogeneric family Magnapinnidae was observed swimming close to the seafloor at 6212 m. The estimated mantle length of the squid was ca. 10 cm. The long slender terminal arm and tentacle filaments characteristic of adult Magnapinna were not obvious in the video. The filaments may have been contracted or may not yet have developed. This observation is the first record of squid at hadal depths and extends the known bathymetric range for any squid by 1477 m; an increase of ca. 30%. We also observed four cirrate octopods between 6212 and 6224 m. Although the video quality was poor, these octopods did not appear to be the same species as those reported previously in the Java Trench. These observations extend the known hadal occurrence of cirrates, and cephalopods in general, from the Indian Ocean to the equatorial North Pacific Ocean, suggesting that their global presence in depths > 6000 m may be more extensive than previously recognized.

Publications describing genomes of various cephalopod species have recently proliferated. Some papers have involved large geographic distances between the collection locality of sequenced specimens and the type locality of the presumed species. However, cryptic species have been demonstrated in many cephalopods. Therefore, even if the sequenced specimen is very similar morphologically to the species in question, the likelihood that it is a member of the species in question decreases with increasing distance from the type locality. An associated problem is that many publications do not provide information adequate to determine the source locality for the genomic sequence. We reviewed a decade of literature on mitochondrial genomes of cephalopods and found a total of 43 publications containing 48 species within 23 genera. Of the 48 species, only 17 could be evaluated for our geographic question. Distances between sampling locality and type locality of the named species ranged from 0 nautical miles (sampled at type locality) to half-way around the world. Where data were present for distance calculation, the average for the 17 species was 3785 km (2044 nmi).

Heteropods are predatory plankton is gastropods that are important in pelagic ecosystems. However, distributions of large heteropod species are poorly known. Heteropod collections from two midwater sampling programs conducted after the 2010 Deepwater Horizon oil spill (DWHOS): the Offshore Nekton Sampling and Analysis Program (ONSAP) in 2011 and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) in 2015-2018 were used for this study These programs collected over 3,495 heteropods in the two target families from 46 sampling stations in the northern Gulf of Mexico (GOM). The zone along the northeastern GOM continental slope had the greatest species richness and abundances. The family Pterotracheidae (Pterotrachea coronata (Forsskal 1775), Pterotrachea hippocampus(Philippi 1836) and Pterotrachea scutata (Gegenbaur 1855) was the most abundant and contained the largest specimens examined. Common carinariids included Carinaria lamarcki (Peron & Lesuer 1810) and Cardiapoda placenta (Lesson 1830). We found evidence of diet migration in P. coronata and P. scutata but not for C. lamarcki, C. placenta or P. hippocampus. We evaluated body and eye size at capture depth for each species. There was no evidence of eye size increasing relative to body size with depth among the five species and relative eye size is species-specific. However, it was observed that vertical migrators had a different eye-type than the non-migrators. We determined that pterotracheids have smaller eyes relative to their total body size than carinariids. The allometric pattern of eye growth differed in P. scutata from those of the other species which could indicate that a factor other than depth plays a part in heteropod eye development. This is the first comprehensive study of large heteropods in the northern GOM which provides an important baseline for continued study of this pelagic gastropod.

Cephalopods are important members of deep-sea communities. However, the preference of many incirrate octopods for rocky substrate makes them largely unavailable with traditional sampling methods such as trawls. Therefore, much remains to be discovered about their diversity. This study focuses on the diversity and distribution of bathyal incirrate species in the western North Atlantic. We used observations from remotely operated vehicle (ROVs) videos, augmented by museum specimens and records from the Ocean Biogeographic Information System (OBIS), to compile a summary of the diversity of bathyal incirrates in the study area and their general distribution. In 22,861 approximately 5-min ROV video clips, we counted 2017 unique incirrate octopod individuals representing at least seven different species. Across observation types, the most common species we recorded were Bathypolypus bairdii Verrill, 1873, Graneledone verrucosa Verrill 1881, Muusoctopus spp., Scaeurgus unicirrhus Delle Chiaje in Ferussac & Orbigny, 1841, Pteroctopus tetracirrhus Delle Chiaje, 1830, and Tetracheledone spinicirrus Voss, 1955.

The performance of DNA metabarcoding approaches for characterizing biodiversity can be influenced by multiple factors. Here, we used morphological assessment of taxa in zooplankton samples to develop a large barcode database and to assess the congruence of taxonomic identification with metabarcoding under different conditions. We analysed taxonomic assignment of metabarcoded samples using two genetic markers (COI, 18S V1-2), two types of clustering into molecular operational taxonomic units (OTUs, ZOTUs), and three methods for taxonomic assignment (RDP Classifier, BLASTn to GenBank, BLASTn to a local barcode database). The local database includes 1042 COI and 1108 18S (SSU) barcode sequences, and we added new high-quality sequences to GenBank for both markers, including 109 contributions at the species level. The number of phyla detected and the number of taxa identified to phylum varied between a genetic marker and among the three methods used for taxonomic assignments. Blasting the metabarcodes to the local database generated multiple unique contributions to identify OTUs and ZOTUs. We argue that a multi-marker approach combined with taxonomic expertise to develop a curated, vouchered, local barcode database increases taxon detection with metabarcoding, and its potential as a tool for zooplankton biodiversity surveys.

In total, 90 gelatinous spheres, averaging one meter in diameter, have been recorded from ~ 1985 to 2019 from the NE Atlantic Ocean, including the Mediterranean Sea, using citizen science. More than 50% had a dark streak through center. They were recorded from the surface to ~ 60–70 m depth, mainly neutrally buoyant, in temperatures between 8 and 24°C. Lack of tissue samples has until now, prohibited confirmation of species. However, in 2019 scuba divers secured four tissue samples from the Norwegian coast. In the present study, DNA analysis using COI confirms species identity as the ommastrephid broadtail shortfin squid Illex coindetii (Vérany, 1839); these are the first confirmed records from the wild. Squid embryos at different stages were found in different egg masses: (1) recently fertilized eggs (stage ~ 3), (2) organogenesis (stages ~ 17–19 and ~ 23), and (3) developed embryo (stage ~ 30). Without tissue samples from each and every record for DNA corroboration we cannot be certain that all spherical egg masses are conspecific, or that the remaining 86 observed spheres belong to Illex coindetii. However, due to similar morphology and size of these spheres, relative to the four spheres with DNA analysis, we suspect that many of them were made by I. coindetii.

Summer plankton surveys were conducted in 2015-2017 to characterize the distribution and abundance of squid paralarvae in epipelagic waters of the northern Gulf of Mexico (Gulf). Paralarvae present at stations sampled were from 12 families, with the most abundant being Ommastrephidae (flying squids), Enoploteuthidae (armed squids) and Onychoteuthidae (hooked squids). Mean density and percent frequency of occurrence for squid paralarvae across all surveys was 8.8 paralarvae 1000 m(-3) and 76%, respectively. Julian day, salinity, sea surface height (SSH) and time of day were identified as influential environmental variables in generalized additive models (GAMs). Paralarval densities peaked during early morning and late evening sampling times, which is in accord with diel vertical migration patterns. Densities increased in early July, in areas with low SSH and lower salinity (28-35 psu), indicating upwelling areas and proximity to inflow from the Mississippi River represent productive early life habitats for squid. Results suggest that oceanic squid spawn in the northern Gulf in the summer exploiting the position of mesoscale oceanographic features and the extension of freshwater discharges from the Mississippi River.

Guy Harvey Oceanographic Center, Halmos College of Arts and Sciences, Nova Southeastern University, Dania Beach, FL, United States, Department of Biological Sciences, Institute of Environment, Florida International University, North Miami, FL, United States, NMFS National Systematics Laboratory, National Museum of Natural History, Washington, DC, United States, Harbor Branch Oceanographic Institution at Florida Atlantic University, Fort Pierce, FL, United States

The legend of the "kraken" has captivated humans for millennia, yet our knowledge of the large deep-sea cephalopods that inspired this myth remains limited. Conventional methods for exploring the deep sea, including the use of nets, manned submersibles, and remotely operated vehicles (ROVs), are primarily suited for studying slow-moving or sessile organisms, and baited camera-traps tend to attract scavengers rather than predators. To address these issues, unobtrusive deep-sea camera platforms were developed that used low-light cameras, red illuminators, and bioluminescence-mimicking lures. Here, we report on several opportunistic deployments of these devices in the Wider Caribbean Region where we recorded several encounters with large deep-sea squids, including the giant squid Architeuthis dux Steenstrup 1857, Pholidoteuthis adami Voss 1956, and two large squid that may be Promachoteuthis sp. (possibly P. sloani Young et al. 2006). These species were recorded between depths of 557 and 950 m. We estimate the Mantle Lengths (ML) of Promachoteuthis were -1.0 m, the ML of the Pholidoteuthis was -0.5 m, and the ML of the Archtiteuthis was -1.7 m. These encounters suggest that unobtrusive camera platforms with luminescent lures are effective tools for attracting and studying large deep-sea squids.