Summer vertical distribution of paralarval gonatid squids in the northeast Pacific

The vertical distribution patterns of paralarvae from severalabundant cephalopod taxa were examined from depth-stratifiedtows in the northeast Pacific (44–56°N, 145–165°W)during three summer surveys in 1999–2001. A total of 309cephalopods representing 10 taxa in three families were collected.Gonatid squids composed 97% of the total catch, and the mostnumerous taxa were Berryteuthis anonychus (59% of the totalcatch), Gonatus spp. (21%) and Gonatopsis borealis (17%). B.anonychus and Gonatus spp. were both most abundant in the upper20 m; catches of both taxa varied significantly with depth andwere significantly higher above the thermocline than in andbelow the thermocline. Gonatopsis borealis was collected mostlybetween 20 and 50 m, and catches were significantly higher inthe thermocline than above and below the thermocline. Paralarvaeof the three major taxa showed no evidence of diel verticalmigration. Mantle lengths of Gonatus spp. and G. borealis eachvaried significantly with depth, and Gonatus spp. showed a strongpositive correlation between mantle length and depth.     

Statolith shape and microstructure in studies of systematics, age and growth in planktonic paralarvae of gonatid squids (Cephalopoda, Oegopsida) from the western Bering Sea

The microstructure, morphology and ontogenetic development ofstatoliths and age and growth of 405 planktonic paralarvae and117 juveniles belonging to 10 species of gonatid squids (Cephalopoda,Oegopsida) were studied in the region of the continental slopein the western part of the Bering Sea (57°00'–61°30'N,163°00'E–179°20'W). The statolith microstructureof all species was characterized by the presence of a largedroplet-shaped nucleus and bipartite postnuclear zone dividedinto two by the first stress check, except for Berryteuthismagister which had only one stress check and an undivided postnuclearzone. In Gonatus spp., completion of development of the postnuclearzone coincided with full development of the central hook onthe tentacular club. Daily periodicity of statolith growth incrementswas validated by maintaining 13 paralarvae of the four mostabundant species in captivity. All species might be subdividedinto two groups based on statolith microstructure, i.e. specieswith a central position of the nucleus within the first statolithcheck (Gonatopsis spp., Egonatus tinro and B.magister) and specieswith the nucleus shifted to the inner side of the first statolithcheck (Gonatus spp.). Comparative analysis of statolith morphologyshowed that paralarval statoliths have species-specific charactersthat allowed the construction of keys to identify species ofgonatid paralarvae based on their statoliths. Analysis of paralarvalgrowth using statoliths revealed that these cold-water planktonicgonatid paralarvae have fast growth rates, attaining a mantlelength of 7–10 mm at 15–20 days and 20–25mm at 35–70 days.     

Evolutionary relationships among squids of the family Gonatidae (Mollusca: Cephalopoda) inferred from three mitochondrial loci

The oceanic squid family Gonatidae (Mollusca: Cephalopoda) is widely distributed in subpolar and temperate waters, exhibiting behavioral and physiological specializations associated with reproduction. Females of several species undergo muscular degeneration upon maturation; origins of this complex morphogenic change are unknown, hindering our understanding of ecological and morpho-physiological adaptations within the family. To provide further information regarding the evolutionary relationships within Gonatidae, three mitochondrial loci (12S rRNA, 16S rRNA, and cytochrome c oxidase subunit I) were analyzed for 39 individuals representing fourteen gonatid and six outgroup cephalopod species. In addition to elucidating relationships among gonatids, molecular data provided more information than morphological data for problematic specimens. Although some data sets are incongruent or have low nodal support values, combined molecular analysis confirms the presence of gonatid groups previously established by morphological characteristics (i.e., possessing radular teeth in seven longitudinal rows and muscular mantle tissue). These characteristics are basal to taxa possessing radular teeth in five longitudinal rows and less muscular mantle tissue, indicating that the derived forms are those species exhibiting physiological adaptation such as tissue degeneration upon maturation and egg brooding.     

Distribution of pelagic squids Abraliopsis Joubin, 1896 (Enoploteuthidae) and Pterygioteuthis P. Fischer, 1896 (Pyroteuthidae) (Cephalopoda,Decapodiformes, Oegopsida) in the Mexican Pacific

The oegopsid squids Abraliopsis and Pterygioteuthis are abundant and diverse genera with taxonomic and distributional problems. Identification and distribution of species in the Mexican Pacific has been somewhat controversial. Here are provided a large series of new records for Abraliopsis affinis, Abraliopsis falco, Pterygioteuthis gemmata, Pterygioteuthis giardi and Pterygioteuthis hoylei from the Gulf of California and off the SW coast of Mexico. All five species were collected in the central or the southern Gulf of California, or in both. Abraliopsis affinis was found in seven samples with a total of 48 specimens, from 21°59'' to 24°53''12"N. Abraliopsis falco was much less represented in the samples (14 specimens) but it was found in 10 localities, four of which correspond to the central-southern Gulf of California (north to 27°44''53"N) and six to SW Mexico (south to 16°49''18"N). In the case of Pterygioteuthis gemmata, only two records (three specimens) were obtained, both in the SW Gulf of California, while Pterygioteuthis giardi (nine specimens) records were all from the central Gulf of California (27°44''53” to 25°39''59"N). In the case of Pterygioteuthis hoylei (nine specimens), material was obtained in six localities, also in a restricted latitudinal range (24°23''48” to 25°56''56"N).     

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.     

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 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     

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     

The cells that secrete the beaks in octopods and squids (Mollusca,Cephalopoda)

A single layer of cell secrets the hard cephalopod beaks. The beccublasts are tall columnar cells that separate the beak from the surrounding buccal muscles, and must serve to attach these muscles to the beak. Within the cell layer there are three types of cells. The first, and most frequently found contain cell-long fibrils. These fibrils may have contractile and tensile properties. Complex trabeculae extend from the beccublasts into the matrix of the beak. The fibrils are attached to these trabeculae and at the other end of the cells they are anchored near to the beccublast-muscle cell interface, closely associated with the muscles that move the beak. The second group of cells contain masses of endoplasmic reticulum the cysternae of which are arranged along the long axis of the cell. These cells also contain dense granules and are probably the major source of beak hard tissue. It is probable that each cell secretes its own column of beak hard tissue. The third group of cells cells contains a mixture of fibrils and secretory tissue. In the beccublast layer there are changes in the proportion of the three types of cells depending upon the region sampled. In the region where growth is most active there are mostly secretory cells, whereas near the biting and wearing tip there are mainly anchoring type cells.     

Retinal Development and Ommin Pigment in the Cranchiid Squid Teuthowenia pellucida (Cephalopoda: Oegopsida)

The cranchiid Teuthowenia pellucida, like many deep-sea squid species, possesses large eyes that maximise light sensitivity in a nearly aphotic environment. To assess ontogenetic changes in the visual system, we conducted morphometric and histological analyses of the eyes using specimens from New Zealand collections. While the ratio between eye diameter and mantle length maintained a linear relationship throughout development, histological sections of the retina revealed that the outer photoreceptor layer became proportionally longer as the animal aged, coincident with a habitat shift into deeper, darker ocean strata. Other retinal layers maintained the same absolute thickness as was observed in paralarvae. Granules of the pigment ommin, normally located in the screening layer positioned at the base of the photoreceptors, were also observed at the outer end of the photoreceptor segments throughout the retina in young and mid-sized specimens. Early developmental stages of this species, dwelling in shallow waters, may therefore rely on migratory ommin to help shield photoreceptors from excess light and prevent over-stimulation. The oldest, deeper-dwelling specimens of T. pellucida examined had longer photoreceptors, and little or no migrated ommin was observed; we suggest therefore that short-term adaptive mechanisms for bright light conditions may be used primarily during epipelagic, early life stages in this species.     

Possible imitation of jellyfish by the squid paralarvae of the family Gonatidae (Cephalopoda,oegopsida)

Paralarval behaviour of eight species of the family Gonatidae (Teuthoidea, Cephalopoda) was examined in small 3–1 aquaria on board ship during planktonic surveys, which were carried out above and off the continental slope of the western part of the Bering Sea. Undisturbed paralarvae moved in aquaria with an average frequency of 15–20 mantle contractions per minute. In response to a sudden disturbance (flash of light, impact to the aquarium wall) squids exhibited a defensive body posture, relaxing the mantle and pulling the head with tentacles and arms into the mantle cavity, thereby becoming similar in appearance, size and colour to small jellyfishesAglantha digitalis (Hydromedusae).     

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-spawned gonatid squid Gonatus onyx, caught between 1350 and 1420 m over a bottom depth of 2100 m in the San Clemente Basin off San Diego, California. It was found that the shape and size of the hatchling statolith were similar to those of the first-check statolith observed in paralarvae and small juveniles of G.onyx. The inner part of the bipartite postnuclear zone (= first-check statolith) is formed during late embryo-genesis, and the first check within the statolith microstructure must be considered as a starting point of increment counting for age estimation of Gonatus spp.      

Different types of photophore in the oceanic squids Octopoteuthis and Taningia (Cephalopoda: Octopoteuthidae)

The oceanic squid Octopoteuthis danue Joubin has one type of photophore on the head, body and arms, but another type on the eight arm tips. The first type has acomplexcapillary network, with elastic walls and a thick reflector. The arm tip organs have no such capillary core but a dense matrix containing paracrystalline assemblies.
Taningia danae Joubin (the only other genus in the family Octopoteuthidae) has only two large arm tip photophores. These are similar in their general organization to the arm tip photophores of Octopoteuthis , but their detailed structure is quite different.
There has evidently been independent evolution of photophores in this family of squids.     

Coral in Alaska: distribution,abundance, and species associations

To help identify fishery management actions that minimize the adverse impacts of fishing activities on corals in Alaska, the distribution and abundance of corals were analyzed based on trawl survey data collected during 1975–1998. We also examined the species of commercially managed fish that are associated with coral. Soft corals, primarily Gersemia sp. (=Eunephthya sp.), were the most frequently encountered corals in the Bering Sea. In the Aleutian Islands gorgonian corals, primarily in the genera Callogorgia, Primnoa, Paragorgia, Thouarella, and Arthrogorgia were the most common corals. In the Gulf of Alaska, gorgonian corals, primarily in the genera Callogorgia and Primnoa, and cup corals, primarily `Scleractinia unidentified', occurred most frequently. The Aleutian Islands area appears to have the highest abundance and diversity of corals. Some fish groups are associated with particular types of coral. Rockfish (Sebastes spp. and Sebastolobus alascanus) and Atka mackerel (Pleurogrammus monopterygius) were the most common fish captured with gorgonian, cup, and hydrocorals, whereas flatfish and gadids were the most common fish captured with soft corals.     

Ontogeny of the fused tentacles in three species of ommastrephid squids (Cephalopoda, Ommastrephidae)

Abstract. The tentacles of ommastrephid squids fuse during embryonic development and remain fused as they grow through hatching, but eventually separate to become two fully functional adult tentacles. The external anatomy of individuals at several post‐hatching ontogenetic stages of three species of ommastrephid squids (Ommastrephes bartramii, Sthenoteuthis oualaniensis, and Hyaloteuthis pelagica) was examined using scanning electron microscopy and morphometrics. The fusion of the transverse muscle mass of the tentacles was examined using light microscopy. Five ontogenetic stages of tentacle separation were defined based on landmark features such as the extent of the fusion and the presence of suckers or sucker buds at the distal tip. The total tentacle length and fused tentacle length reached a maximum when the dorsal mantle length (ML) equaled 3–4 mm (H. pelagica) or 4–6 mm (O. bartramii, S. oualaniensis), and then decreased with increasing ML. The average split length (measured from the base of the tentacles to the point of tentacle fusion) increased gradually with increasing ML, and the separate tentacle diameter was roughly half the diameter of the fused portion at all sizes. In all three species, separation of the fused tentacles began earlier in development (2–3‐mm ML) and was more advanced at smaller sizes than previously reported. The sizes presented here are conservative because excess epithelium at the location of the split may disguise the actual site of separation. Post‐separation tentacles were much shorter than the arms, and the carpal region appeared torn in 2 of the 4 specimens of S. oualaniensis examined. Finally, none of the original distal tip suckers were retained on the post‐separation tentacles of S. oualaniensis. These observations are consistent with the hypothesis that the tentacles separate gradually then rupture at the “wrist” (presumptive carpus), and argue against the possibility of prey capture by the fused tentacles.     

Systematics and distribution of the New Zealand onychoteuthid fauna (Cephalopoda: Oegopsida), including a new species, Notonykia nesisi sp. nov.

Onychoteuthid squids are among the most common cephalopods found in New Zealand waters, and comprise a major portion of the regional diets of teuthophagous marine mammals. Although several recent publications have addressed aspects of various species’ biology and reproduction, the systematics of the group remains poorly understood. Herein the ontogenetic and adult morphologies of regionally occurring known species of the genera Moroteuthis, Onychoteuthis, and Notonykia are redescribed, and Notonykia nesisi sp. nov. is described for the first time. Ontogenetic and sexually dimorphic variation in characters and character states associated with body proportions, and beak, radula, tentacular hook, palatine tooth and gladius morphologies are also described and compared between local onychoteuthid taxa for the first time.     

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.     

Annual distribution and abundance of Ceratium dens (Peridinales: Ceratiaceae) in the Gulf of California, Mexico

Ceratium dens distribution in the Gulf of California was studied based on three oceanographic campaigns, monthly abundance (1995-96) and during three red tide events in Mazatlán Bay. 52 phytoplankton samples with a Bongo net and 64 microns mesh light, during the year 120 water samples with a van Dorn bottle were collected in two sampling stations and from three red tide events. All samples were counted by the inverted-microscope method. The results showed that C. dens was present in the upper Gulf of California and surroundings of Cabo San Lucas. Two peaks were observed during spring and autumn in Mazatlán Bay during 1995-1996. The highest densities (20-360 cells.-l-1) were observed in coastal areas, whereas the lowest densities (1-14 cells.-l-1) were recorded in the open sea. During red tide events in 1985, 1989 and 1997, 144,000-256,000 cells.-l-1, 100,000-400,000 cells.-l-1, and 189,000-592,000 cells.ul-l was observed, respectively. During the red tide events C. dens varied, although sometimes was replaced by Skeletonema costatum or Pseudonitzchia spp and Ceratium furca. C. dens, seems to prefer areas with high productivity.