Marine flora and fauna of the eastern United States Mollusca: Cephalopoda

The cephalopods found in neritic waters of the northeastern United States include myopsid and oegopsid squids, sepiolid squids, and octopods. A key with diagnostic illustrations is provided to aid in identification of the eleven species common in the neritic waters between Cape Hatteras and Nova Scotia; included also is information on two oceanic species that occur over the continental shelf in this area and that can be confused with similar-looking neritic species. Other sections comprise a glossary of taxonomic characters used for identification of these species, an annotated systematic checklist, and checklists of the 89 other oceanic species and 18 Carolinian and subtropical neritic species that might occur occasionally off the northeastern United States. (PDF file contains 30 pages.

Aspects of the early life history of Loligo pealei (Cephalopoda:Myopsida)

The long-finned squid Loligo pealei was the most common squid collected in 2 years of zooplankton sampling over the Middle Atlantic Bight off New Jersey and Virginia. Planktonic specimens of L. pealei were found in that area during spring, summer, and fa ll; there were no indications of multiple stocks. This species was captured in waters with a salinity range of 31.5 to 34.0 ppt, and was confined to coastal waters except when current conditions, such as the passage of a Gulf Stream eddy, resulted in strong, offshore surface transport. While abundances were greater in night surface samples, larger specimens occurred in night subsurface samples indicating ontogenetic descent. Tentacle length was closely correlated with dorsal mantle length (DML) in preserved specimens of less than 4.5 mm DML, indicating that tentacles are noncontractile in newly hatched specimens. This may be part of a major discontinuity in the development of L. pealei which separates hatchlings from juvenile

A Multispecies Aggregation of Cirrate Octopods Trawled from North of the Bahamas

Two cruises in the western North Atlantic collected 38 trawl samples between the Bahamas and New England. Of the 22 cirrate octopods taken in these samples, 17 came from the area north of the Bahamas. Pooled catch rate (specimens per hour of bottom trawling time) was significantly higher north of the Bahamas than in any other area sampled. Although the taxonomy of these gelatinous benthopelagic cephalopods is not yet settled, morphological characters from these specimens indicate that this aggregation includes at least four species. Only one species (Cirrothauma murrayi) was widely distributed in these samples

A Multispecies Aggregation of Cirrate Octopods Trawled from North of the Bahamas

Two cruises in the western North Atlantic collected 38 trawl samples between the Bahamas and New England. Of the 22 cirrate octopods taken in these samples, 17 came from the area north of the Bahamas. Pooled catch rate (specimens per hour of bottom trawling time) was significantly higher north of the Bahamas than in any other area sampled. Although the taxonomy of these gelatinous benthopelagic cephalopods is not yet settled, morphological characters from these specimens indicate that this aggregation includes at least four species. Only one species (Cirrothauma murrayi) was widely distributed in these samples

Distribution, relative abundance and developmental morphology of paralarval cephalopods in the Western North Atlantic Ocean

Paralarval and juvenile cephalopods collected in plankton samples on 21 western North Atlantic cruises were identified and enumerated. The 3731 specimens were assigned to 44 generic and specific taxa. This paper describes their spatial and temporal distributions and their developmental morphology. The smallest paralarvae recognized for a number of species are identified and illustrated. The two most abundant and most frequently collected taxa were identifiable to species based on known systematic characters of young, as well as on distribution of the adults. These were the neritic squids Loligo pealeii and Illex illecebrosus collected north of Cape Hatteras, both valuable fishery resources. Other abundant taxa included two morphotypes of ommastrephids, at least five species of enoploteuthids, two species of onychoteuthids, and unidentified octopods. Most taxa were distributed widely both in time and in space, although some seasonal and mesoscale-spatial patterns were indicated. The taxa that appeared to have distinct seasonal distribution included most of the neritic species and, surprisingly, the young of the bathypelagic cranchiids. In eight seasonal cruises over the continental shelf of the middle U.S. Atlantic states, neritic taxa demonstrated approximately the same seasonal patterns during two consecutive years. Interannual differences in the oceanic taxa collected on the shelf were extreme. The highest abundance and diversity of planktonic cephalopods in the oceanic samples were consistently found in the vicinity of the Gulf Stream. Only eight of the oceanic taxa appeared to have limited areal distributions, compared with twelve taxa that were found throughout the western North Atlantic regions sampled in this study. Many taxa, however, were not collected frequently enough to describe seasonal or spatial patterns. Comparisons with published accounts of other cephalopod surveys indicate both strengths and weaknesses in various sampling techniques for capturing the young of oceanic cephalopods. Enoploteuthids were abundant both in our study and in other studies using midwater trawls in several areas of the North Atlantic. Thus, this family probably is adequately sampled over its developmental range. In contrast, octopoteuthids and chtenopterygiids are rare in collections made by small to medium-sized midwater trawls but are comparatively common in plankton samples. For families that are relatively common in plankton samples, paralarval abundance, derived similarly to the familiar ichthyoplankton surveys of fisheries science, may be the most reliable method of gathering data on distribution and abundance. (PDF file contains 58 pages.

Numerous Sublinear Sets of Holes in Sediment on the Northern Mid-Atlantic Ridge Point to Knowledge Gaps in Understanding Mid-Ocean Ridge Ecosystems

On 13 July 2004, during an expedition exploring biodiversity along the northern Mid-Atlantic Ridge, an ROV dive recorded videos of numerous sublinear sets of holes in sediment at ca. 2,082 m depth. The location was north of the Azores. Each set appeared track-like. Lengths of individual series ranged from < 1 m to many meters. Each was straight or gently curved. Some series intersected or crossed. Close examination of the holes showed them to be elongate, with the long axis parallel to the axis of the series. The holes were ca. 6 × 1.5 cm, with distance between holes similar to hole length. The holes that appeared to be most recently formed were each surrounded by raised sediment. Holes that appeared older were partly filled with sediment and the raised surrounding sediment was less obvious. Overall, these lebensspuren created small-scale heterogeneity in the local soft-bottom benthic ecosystem. The source of the holes or how they were constructed is unknown, but the raised sediment may indicate excavation by an infaunal organism or digging and removal by e.g., a feeding appendage of a large epifaunal animal. None of our closeups showed any sign of living organisms inhabiting the holes. Whether the holes were connected beneath the sediment surface was not visible. The traces observed are reminiscent of ichnofossils reported from deep marine facies. We hope that future studies of the lebensspuren we report here will resolve the mystery of what created them.publishedVersio

In situ observations on Brachioteuthis beanii Verrill: paired behaviour, probably mating (Cephalopoda, Oegopsida)

A behaviour that has never been seen in cephalopods was observed thre times in large aggregation of Brachioteuthis beanii Verrill, 1881. During a series of submersible dives off Cape Hatteras, North Carolina, estern U.S., three pairs of Brachioteuthis were seen, and one pair was video-taped. In all three pairs one squid grasped the other by the posterior mantle in its arm crown. This paired behaviour involved brief periods in which the grasped squid bent its head and body posteriorly and vigorously moved its arms around the head and mantle opening of the grasping squid. Although we were unable to capture any of the coupling pairs to determine their stage of maturity, we believe this unusual activity represents mating behaviour

Unusual incirrate octopods from the South Shetland Islands, Antarctica, including Bathypurpurata profunda, a newly discovered genus and species of deepwater pygmy octopod (Cephalopoda)

Among the many octopods collected during recent Antarctic trawling were several species that do not belong to the common Antarctic pareledonin fauna. Three species are either poorly known or new to science, so we describe their morphology and anatomy. A very small (23 mm dorsal mantle length, ML) mature female of a fragile, dark purple species without an ink sac has suckers in a single series and proportionally huge salivary glands. We consider it to be a new genus and species. A single Graneledone antarctica Voss is unusual because it is the largest reported specimen (104 mm ML) and the first mature female. Six “Bentheledone” from a single deep (3213 m) sample and another, mature male caught nearby over five years later, may be B. albida (Berry), until now known only from the holotype. They are characterized by tiny posterior salivary glands, a small triangular calamus and small almost circular ligula