A phylogenetic study of the squid family Onychoteuthidae (Cephalopoda: Oegopsida)

The oegopsid squid family Onychoteuthidae presently comprises six genera (Moroteuthis, Onychoteuthis, Ancistroteuthis, Kondakovia, Onykia and Chaunoteuthis) but the status of some of these is still uncertain. An interdisciplinary study was undertaken to clarify the phylogenetic relationships, which included a morphological approach (morphometric analysis), and a molecular study of a mitochondrial gene portion (l-rRNA gene, 16S). The morphometric analysis identified two groups, one including some Onychoteuthis and some Moroteuthis knipovitchi, and another including the remaining genera or species. At the intrageneric level, M. knipovitchi appears to be separated from the other species of the genus; M. robusta is closely related to M. ingens and M. pacifica. Morphometric analysis confirmed that Kondakovia longimana is different from M. ingens. Likewise, Onychoteuthis was clearly separated from the other genera, but there is neither geographical grouping nor morphometric differentiation of the Onychoteuthis species with the parameters measured. Some specimens were apparently intermediate between the Onychoteuthis and Ancistroteuthis groups. On a molecular basis, the Onychoteuthidae appeared to be monophyletic. Monophyly of the genus Moroteuthis (four species studied) was not strongly supported: M. knipovitchi was distinct from the others. The molecular analysis showed three Hawaiian species, Onychoteuthis compacta, O. sp. B and O. sp. C, to be closely related. The gene sequence for the newly created species of Onykia is clearly different from all the others, indicating that it is a true species.     

Terminal spawning in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae)

Maturation in the onychoteuthid squid Moroteuthis ingens was found to be irreversible, with death following shortly after sexual maturation and spawning. Both males and females were found with spent gonads. The ovary reaches very large sizes in mature females and probably prevents feeding by constricting the caecum. There was also a marked difference in the tissue integrity between immature females and females which had reached sexual maturity. Mature and spent females showed advanced tissue breakdown with individuals having a thin mantle wall with an inelastic, gelatinous appearance. Histological examination of the mantle wall revealed that the tissue breakdown was due to a drastic histolysis of muscle tissue and, to a lesser extent, collagen fibres. Mature males also showed some tissue breakdown and loss of muscle fibres but this was not as dramatic as in the females. These features are considered in relation to processes contributing to terminal maturation in M. ingens.     

Food spectrum of the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

Prey species of the deepwater squid Moroteuthis ingens were examined for 37 large specimens captured in New Zealand waters. Caecum contents were predominantly less than 80% full and covered a range of digestion stages. The diet consisted of fish (at least seven species, of which four were myctophids) and squid. The most abundant prey was the myctophid Lampanyctodes hectoris, which was represented by 1323 otoliths from 22 caeca. The second most abundant prey was viperfish (Chauliodus sloani) and/or dragonfish (Stomias boa), represented by 537 otoliths from 17 caeca. Individual squid appeared to ingest surprisingly large numbers of fish (up to 100) during a single feeding period and could achieve feeding rates greater than 10% of their body weight per day. While some males appeared to ingest larger numbers of L. hectoris, females targeted significantly larger individuals of L. hectoris thereby ingesting a greater biomass of fish. Received: 31 July 1997 / Accepted: 15 January 1998     

Age, growth and maturation of the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

 Individuals of the deepwater squid Moro- teuthis ingens were obtained from New Zealand waters at depths between 500 and 1452 m. Depth distribution suggested that there was an ontogenetic migration to deeper water by females in association with maturity. Males did not show any clear pattern in their depth distribution. Statolith increment analysis was also undertaken to obtain putative age and life span information. Based on statolith age estimates, M. ingens appears to be predominantly an annual species with the oldest individuals aged at 358 and 393 days for males and females respectively. The form of growth over the size range sampled was linear with females having a growth rate almost twice that of males. Back-calculated hatching dates revealed a peak in hatching in the austral winter between June and August. Maturation in males was more closely related to size rather than age whereas in females the pattern in ovary growth in relation to both mantle length and age was similar. Received: 23 January 1996/Accepted: 29 May 1996     

Distribution and abundance of the squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in the Falkland Islands region of the South Atlantic

The distribution and abundance of the onychoteuthid squid Moroteuthis ingens were assessed for the Patagonian Shelf in the Falkland Islands region. Catch records from the commercial fishery and a research cruise were recorded from 1988 to 1996. Sampling included benthic, pelagic and semi-pelagic trawls and jigging. Moroteuthis ingens was recorded from 1,414 stations out of a total of 9,060 stations with 79.9% of all positive stations being from benthic trawls. Catch size ranged up to approximately 3,000 kg. The length frequency analysis and maturity indices suggested a major recruitment onto the shelf in September with a movement off the shelf during winter. There appears to be a lack of mature females on the Patagonian Shelf, indicating that females migrate into deeper offshore water to spawn. Observations of predation on Moroteuthis ingens on the Patagonian Shelf, along with a literature review, revealed that at least 4 mammal, 17 bird and 13 fish species prey on this squid. Received: 30 October 1997 / Accepted: 11 April 1998     

The use of beaks as tools for biomass estimation in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

Beak lengths (lower rostral length and upper rostral length) were taken for a sample of Moroteuthis ingens which were captured on the Chatham Rise, New Zealand. Beak lengths were plotted against both mantle length and wet weight to determine the relationship between these parameters for future use in biomass estimates in predator analysis. Although M. ingens is markedly sexually dimorphic, with females reaching 5 times the weight of males, there was no obvious sexual dimorphism in either lower or upper rostral length. This resulted in sex-specific relationships between both LRL and mantle length, LRL and weight; and URL and mantle length, and URL and weight. Males appeared to have a curvilinear relationship between beak length and mantle length and beak length and weight (even for log-transformed data). There was also considerable spread in the data in the plot between beak length and weight for females of similar weight. These characteristics of the data makes biomass estimates based on rostral length measurements for this species difficult. Other beak parameters may prove more useful for estimating biomass of M. ingens.     

Statolith shape and microstructure as indicators of ontogenetic shifts in the squid Gonatus fabricii (Oegopsida, Gonatidae) from the Norwegian Sea

Statolith shape and microstructure were studied in 151 specimens of the common arctic squid Gonatus fabricii (7.3–322 mm pen length) collected in the southern Norwegian Sea. Statolith development and growth both comprised two main periods, which corresponded with the epipelagic and meso-bathypelagic ontogenetic periods of G. fabricii. During the epipelagic period (pen length range from 3 to 50–60 mm), statoliths quickly developed from the droplet-like form in early paralarvae to the pre-definite stage in juveniles (30–50 mm pen length). Paralarval and juvenile statoliths grew with high growth rates, and their microstructure contained narrow first-order growth increments. Three main growth zones (Z1, Z2, Z3) developed during this period, being well distinguished from each other by specific patterns of microstructure and separated from each other by distinct checks. During the meso-bathypelagic period (from 50–60 to 322 mm pen length), statoliths hardly changed their shape and grew very slowly. Only one growth zone (Z4) was formed within the statolith microstructure, characterized by disappearance of the first growth increments and formation of specific second-order bands. Each second-order band consisted of approximately seven first-order increments. If the assumption “one increment-one day” is true for G. fabricii, the squid would then be a slow-growing animal with a life span for both sexes not exceeding 2 years. Accepted: 25 May 1999     

Structure of the reproductive system of the squid Thysanoteuthis rhombus (Cephalopoda: Oegopsida)

The structure of the reproductive systems of mature males and females of the nektonic, oceanic squid Thysanoteuthis rhombus are described. The main peculiarities of the female system are relatively low capacity oviducts, set in a tight spiral, and hypertrophically developed oviducal glands with a very large second section. The male reproductive system is characterized by a long, narrow Needham's sac containing 10–15 large spermatophores 80–100 mm in length. The mesentery supporting the gonad, and protruding into it dorsally, is a characteristic feature in both sexes. The hectocotylus structure differs markedly from that in other squids and resembles that of sepiids. The reproductive system of T. rhombus possesses primitive features (pattern of gonad attachment and hectocotylus) but mostly secondary characters (small oviducts, very large oviducal glands and ovary). The complex morpho-ecological adaptations of T. rhombus are reflected in the distinctive features of the reproductive system.     

Statolith microstructure and age of early life stages of planktonic squids Galiteuthis phyllura and Belonella borealis (Oegopsida, Cranchiidae) from the northern North Pacific

Statolith morphology and microstructure were studied in twocommon species of panktonic cranchiid squids, Belonella borealis[four juveniles with mantle length (ML) 375–450 mm] andGaliteuthis phyllura (13 paralarvae and juveniles, ML 9–235mm),caught near the bottom and in pelagic layers over the continentalslope of Siberia in the northwest Bering Sea. The total numberof growth increments within the statoliths ranged from 277 to294 in B.borealis and from 10 to 209 in G.phyllura. Assumingthat these increments were produced daily, both species growrapidly in length (daily growth rate = 1.13mm day^–1 duringthe first 8–10 months of their juvenile phase in the mesopelagiclayers, prior to migration into deeper waters for maturation.     

Confirmation of winter spawning of Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in the Chatham Rise region of New Zealand

Specimens of the onychoteuthid squid Moroteuthis ingens were collected on the northwest Chatham Rise off the east coast of New Zealand during late June/early July 1997. Trawl depth ranged between 751 and 1,151 m. A total of 89 squid were captured (65 males, 24 females). Except for one immature (stage 2) female, all the individuals collected were either mature (stage 5) or spent (stage 6). There was no significant difference in testis weight between stage-5 and stage-6 males but there was a significant difference in mantle weight and total weight. There was also a significant difference in ovary weight and total weight between stage-5 and stage-6 females but no significant difference in mantle weight. Female fecundity ranged from 84,379 to 286,795 with a mean oocyte size of 2.1 mm. This study confirms that winter is a spawning period for M. ingens and that the Chatham Rise is a spawning region for this species. Accepted: 30 June 2000     

Short communication. Statolith microstructure from hatchlings of the oceanic squid, Gonatus onyx (Cephalopoda, Gonatidae) from the Northeast Pacific

Statolith microstructure was studied in hatchlings of deepwater-spawnedgonatid squid Gonatus onyx, caught between 1350 and1420 m over a bottom depth of 2100 m in the San Clemente Basin off SanDiego, California. It was found that the shape and size of the hatchlingstatolith were similar to those of the first-check statolith observed inparalarvae and small juveniles of G.onyx. The innerpart of the bipartite postnuclear zone (= first-check statolith) is formedduring late embryo-genesis, and the first check within the statolithmicrostructure must be considered as a starting point of increment countingfor age estimation of Gonatus spp.     

A second species of the squid genus <Emphasis Type="Italic">Kondakovia</Emphasis> (Cephalopoda: Onychoteuthidae) from the sub-Antarctic

A new species of squid, Kondakovia nigmatullini, is described based on two specimens from sub-Antarctic waters of the Southwest Atlantic. The new species is characterised by short, broad, rhombic fins, long rostrum of the gladius (~13% ML); very weak development or absence of longitudinal ridges on the mantle surface; some reticulate folds on mantle surface; 23–27 club hooks; subequal funnel/mantle components of the locking apparatus, and a tricuspid rachidian, with small lateral cusps.     

Ontogenetic changes in morphometric and reproductive indices of the squid Gonatus fabricii (Oegopsida, Gonatidae) in the Norwegian Sea

Ontogenetic changes in morphometric and reproductive indices were studied using 166 individuals of the arctic gonatid squid Gonatus fabricii (7.3–322 mm pen length) collected in the southern part of the Norwegian Sea. Body proportions and consistency of the mantle and fins did not change in maturing and mature males. In contrast, during maturation the females first lost their tentacles, then the horny rings of their 4th arm suckers, and the muscular part of their body turned watery and gelatinous. Unlike most squid, G. fabricii females start mating at maturity stage III, and all but one female at stage IV had mated, as well as all spent females. Females had high values of both gonadosomatic index and maturity indices compared to those of the North Pacific gonatids, whereas gonadosomatic index values of males were low, probably due to slow functioning of both testis and spermatophoric gland, and long accumulation of spermatophores in the Needham's sac. It is suggested that the breakdown of female body tissues is an adaptation for a deepwater bathypelagic “brooding” of the negatively buoyant egg-mass caused by the high specific density of the secretion from the nidamental glands in gonatids. Accepted: 25 May 1999     

Intracellular recording from the giant synapse of the squid

1. Recording with glass micropipette electrodes inserted close to the synaptic region, in the presynaptic and in the postsynaptic fibers of the giant synapse in the stellate ganglion of the squid, has been accomplished. 2. The forms of the spike and of the synaptic potential are very much like those reported earlier (Bullock, 1948) from macroelectrodes. The crest time and the rate of fall are labile and depend on the state of fatigue, though the time of initiation of the postsynaptic potential does not. 3. It is concluded after examination of both intra- and extracellular recordings that there is a real synaptic delay of the order of 1 or 2 milliseconds at 15–20°C. 4. There is sometimes a very small and sometimes no visible deflection in the intracellular postsynaptic record attributable to the presynaptic spike. It is concluded that transmission cannot be electrical. 5. The amplitude of the postsynaptic potential can be controlled over some range by the amplitude of the presynaptic potential. 6. Hyperpolarization of the postsynaptic membrane results in increase in amplitude of spikes up to 200 millivolts, in increase in the membrane potential level at which the spike flares up, but in no considerable change in the amplitude in postsynaptic potential. 7. The postsynaptic potential can add to the late falling phase and the undershoot of an antidromic spike in the postfiber but cannot add to the crest or early part of the falling phase. The earliest part of the antidromic spike during which the postsynaptic potential can add is probably a period of refractoriness to electrical shock by analogy with the properties of the axon.     

Sequential isotopic signature along gladius highlights contrasted individual foraging strategies of jumbo squid (Dosidicus gigas)

Background

Cephalopods play a major role in marine ecosystems, but knowledge of their feeding ecology is limited. In particular, intra- and inter-individual variations in their use of resources has not been adequatly explored, although there is growing evidence that individual organisms can vary considerably in the way they use their habitats and resources.

Methodology/Principal Findings

Using δ¹³C and δ¹⁵N values of serially sampled gladius (an archival tissue), we examined high resolution variations in the trophic niche of five large (>60 cm mantle length) jumbo squids (Dosidicus gigas) that were collected off the coast of Peru. We report the first evidence of large inter-individual differences in jumbo squid foraging strategies with no systematic increase of trophic level with size. Overall, gladius δ¹³C values indicated one or several migrations through the squid''s lifetime (∼8–9 months), during which δ¹⁵N values also fluctuated (range: 1 to 5‰). One individual showed an unexpected terminal 4.6‰ δ¹⁵N decrease (more than one trophic level), thus indicating a shift from higher- to lower-trophic level prey at that time. The data illustrate the high diversity of prey types and foraging histories of this species at the individual level.

Conclusions/Significance

The isotopic signature of gladii proved to be a powerful tool to depict high resolution and ontogenic variations in individual foraging strategies of squids, thus complementing traditional information offered by stomach content analysis and stable isotopes on metabolically active tissues. The observed differences in life history strategies highlight the high degree of plasticity of the jumbo squid and its high potential to adapt to environmental changes.     

Bufadienolides from Drimia robusta and Urginea epigea (Hyacinthaceae)

Two bufadienolides, 6beta-acetoxy-3beta,8beta,14beta-trihydroxy-12-oxobufa-4,20,22-trienolide and 14beta-hydroxybufa-3,5,20,22-tetraenolide were isolated from the dichloromethane extract of the bulbs of Drimia robusta and the methanol extract of the bulbs of Urginea epigea, respectively. The bulbs of Drimia robusta also yielded several known compounds, 6beta-acetoxy-3beta,8beta,12beta,14beta-tetrahydroxybufa-4,20,22-trienolide (12beta-hydroxyscillirosidin) from the dichloromethane extract and three common aromatic acids, 4-hydroxy-3-methoxybenzoic acid, 3,4-dihydroxybenzoic acid, and trans-3-(4'-hydroxyphenyl)-2-propenoic acid from the ethyl acetate extract.     

Polymorphic tetranucleotide microsatellites for Cope's giant salamander (Dicamptodon copei) and Pacific giant salamander (Dicamptodon tenebrosus)

We present primers and amplification conditions for 15 microsatellite loci developed for the Cope's giant salamander (Dicamptodon copei), 14 of which are tetranucleotide repeats. Cross-species amplification revealed 10 of these loci to also be polymorphic in the Pacific giant salamander (Dicamptodon tenebrosus). Several loci produced nonoverlapping allelic ranges between the two species and may be useful in species identification. These polymorphic microsatellite loci are potentially useful for future studies of population genetics in dicamptodontid salamanders.