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The measured gross alpha and gross beta activities in the edible muscle tissues of eleven selected marine species along the coast of North Vietnam varied from 10.2 ± 1.5 to 73.2 ± 8.1 Bq/kg (wwt) and from 10.6 ± 0.4 to 68.8 ± 2.8 Bq/kg (wwt), respectively. The lowest gross alpha activity was recorded for bigfin reef squid (Sepioteuthis lessoniana) as a result of its carnivorous diet, and the highest alpha activity was noted for blood cockle (Anadara granosa) as a result of its omnivorous diet. However, the gross beta activities in both carnivorous and omnivorous species were similar. The highest and lowest gross beta activities were observed for narrow-barred Spanish mackerel (Scomberomorus commerson) and for bigfin reef squid and squid (Teuthida), respectively. All three aforementioned species have carnivorous diets. The calculated annual committed effective dose resulting from the consumption of 25 kg of muscle tissue per year varied from 192 to 1375 μS with an average of 689 μS.

The cephalopods are known to be commercially and ecologically important around the world. This group constitutes four major groups, Cuttlefishes, Squids, Octopuses, and Nautilii. The first three groups are present in the Egyptian Mediterranean and Red Seas and constitute a main component in the fisheries industry in Egypt. In order to understand the biology and ecology of any species, its identification should be conducted properly to maximize the accuracy of any study. The present monograph is prepared to demonstrate an identification key for the squid species of order Teuthoidea in the Egyptian waters. This is the second publication demonstrating a first-in-kind identification key for the three major cephalopod groups. The first monograph was about the cuttlefishes. Six Egyptian squid species were recorded; Loligo vulgaris, Loligo forbesi, Loligo duvauceli, Alloteuthis media, Illex coindetii, and Sepioteuthis lessoniana. Four of them; Loligo vulgaris, Loligo forbesi, Alloteuthis medi and Illex coindetii were recorded in the Mediterranean waters, while the other 2 species, Loligo duvauceli and Sepioteuthis lessoniana were recorded in Suez Gulf, Red Sea. Two squid species; Loligo forbesi and Sepioteuthis lessoniana were recorded in both the Mediterranean and Red Seas. Specimens of each species were collected for the purpose of identification using external morphological features. Body structures were separated and drawn by using a zoom stereoscopic microscope provided with a Camera Lucida drawing tube. The body structures were also photographed by a Canon Digital Camera.

Squid Sepioteuthis lessoniana is a sought-after fisheries commodity, leading to a high exploitation rate. This affects the sustainability of Squid (S. lessoniana) resources in wild, especially Spermonde Island. The aim of this study was to determine the population dynamics and the exploitation rate of Squid (S. lessoniana) in the Spermonde Islands of South Sulawesi. The results of the study are expected to provide information on the level of utilization of Squid and as a basis for sustainable management of squid in Spermonde Islands. The present study was conducted from March to July 2019 in Spermonde Islands, South Sulawesi. A survey was performed by direct measurement of the fish captured by local fishermen and merchants. Data collected on length and weight of squid were carried out for 3 or 4 times a week. The results showed length of squid ranged from 06 to 28 cm, the relationship between the length of the weight was negative allometric, the age group consisted of 4, the growth rate (K) of 0.37 per year, the maximum length (L max) of 31.5 cm, the total mortality rate (Z) of 2.85 per year, the natural mortality rate (M) of 0.95 per year, the capture mortality rate (F) of 1.90 per year and the exploitation rate is classified into over-exploitation.

Diversification of marine culture has an effective value for the sustainability of the livelihoods of small fishermen. In addition it can play a role in preventing the threat of utilization that is not environmentally friendly. Cuttlefish is one of the types of marine biota commodity that has high economic value and has the potential to be developed as a fishery diversification community. The purpose of this study was to determine the indicators of the potential of cuttlefish cultivation as a diversification strategy for small fishermen's cultivation and seagrass conservation in the study location. The research method used is the method of direct observation and interviews. Data analysis uses descriptive statistical analysis. The results showed that the average cuttlefish seedlings were 1293.5 individuals / month and the average cuttlefish caught by fishermen landed at TPI Tanjung Luar was 1229 individuals / month consisting of three species namely Sepia latimanus, Sepia pharaonis and Sepioteuthis lessoniana. In addition, marine cultivation has developed into the choice of livelihood for small fishermen, although it is still complementary. Furthermore, the group of farmers plays an active role in preventing local threats from uses that are not environmentally friendly. The conclusion is the diversification of cultivation with cuttlefish community is of strategic value to overcome the problem of the sustainability of small fishing livelihoods and local scale seagrass conservation in the study location. Therefore, diversification of cuttlefish culture can be considered, especially at the scale of small fishermen as a policy of developing seafood products to achieve food security, both at local, regional and national scale.

The accessory nidamental gland (ANG) is part of the reproduction organ in the majority of female cephalopods, including the bigfin reef squid Sepioteuthis lessoniana, an economically important fishery product. Microbes in Alphaproteobacteria, Gammaproteobacteria, and Verrucomicrobia have been suggested to play a role in the maturation of the S. lessoniana ANG and are responsible for its color. However, the bacterial composition and dynamics of the different maturation stages of the ANG remain unclear. In the present study, we surveyed ANG-associated bacterial dynamics in wild-caught S. lessoniana at various developmental stages in different populations over 3 years. The results obtained showed that the ANG bacterial community shifted gradually and decreased in diversity throughout maturation. Verrucomicrobia occupied the ANG during the early stages in large numbers, and was replaced by Bacteroidia, Alphaproteobacteria, and Gammaproteobacteria in the later stages. Flavobacteriales and Alphaproteobacteria both appeared to contribute to pigmentation, while Bacteroidia, Alphaproteobacteria, and Gammaproteobacteria may be involved in enriching the heme biosynthesis pathway in the ANG with the maturation of S. lessoniana. The present results provide an open question of whether S. lessoniana actively selects the bacterial community in the ANG to adjust to its surrounding environment.

Sepioteuthis lessoniana is a widely distributed neritic squid in the Indo-Pacific Ocean. It is an important species in fisheries, but species management is difficult because of inadequate information regarding its life history. The daily growth and δ18O values from the core to the edge of statoliths of S. lessoniana collected in northern Taiwan were analyzed to predict the experienced temperature history along with ontogenetic stages. The probability of occurrence in a given area at each life stage in three seasonal groups was determined using salinity values, deduced and measured temperatures, and the known ecology of S. lessoniana. The results showed that ontogenetic variation in the statolith δ18O values in S. lessoniana reflected the seasonal temperature fluctuation observed in Taiwanese waters, which indicated the reliability of the prediction method. Complex and diverse distribution and movement patterns were observed in the three seasonal groups. The results also indicated the importance of the waters near the coast of northeastern Taiwan as a spawning ground. Based on a model prediction, the distribution of S. lessoniana is likely associated with water temperature and current. A potential migration route from the Penghu Islands to northeastern Taiwan suggests a high level of population connectivity in S. lessoniana in Taiwan. This study provides information on the spatial and vertical distribution of S. lessoniana at various ontogenetic stages, which is essential for resource management and conservation of this commercial species.

MORPHOLOGY, CLASIFICATION, AND DISTRIBUTION OF SQUID FAMILY LOLINGINIDAE. Squids are one of Indonesian export commodities that is produced in frozen, salted, dried or canned, however the information about biology, ecology, habitat and distribution of squid are little known. Squid have ten tentacles equipped with suction, and generates ink to defend against their enemies. Squids are demersal or semi-pelagic animal that lives in the waters column up to a depth of 400 m with diurnal movements. Squids reproduce sexually and by deocious. Squids with family Lolinginidae (genus Lolious) are distributed across the Indonesian waters with temperatures of 8 to 32 C and salinity of 8.5 to 30 ppm. Familly Lolinginidae is grouped into several genera included Afrololigo, Allotheuthis, Dorytheuthis, Heterololigo, Loliolus, Lollinguncula, Pickfordiateuthis, Sepioteuthis, dan Urotheuthis

Indexación: Scopus. According to the vicariant hypothesis proposed by Brakoniecki (1986) the closure of the Sea of Tethys and the opening of the Atlantic Ocean would play an important role in the history of squids of the family Loliginidae, which is reflected in its current neritic distribution. Our study evaluated this hypothesis and alternative ideas to understand the historical biogeography of loliginid squids. This work is based on a phylogenetic hypothesis rebuilt with mitochondrial and nuclear sequences that incorporates the estimation of divergence times and ancestral distribution. Our results sustain that the squids of the family Loliginidae would have originated in the Western Pacific during the Late Paleocene about 59 My, following, during their diversification, at least 20 dispersion and 6 vicariant events. The first vicariant event fragments the ancestral distribution, remaining the ancestor of Sepioteuthis in the south and the subfamily Loligininae in the north. Successive events of dispersion, and some of vicariance (unrelated with the movement of tectonic plates and opening of the Atlantic Ocean), modeled it distribution. Our inference suggest a different origin compared to proposed by Brakoniecki (Tethys Sea), consistent with a center of origin that supports the most diversity of the family, with a predominance of dispersion processes over vicariant events, which explain the present distribution pattern. http://www.lajar.cl/pdf/imar/v45n1/Art%C3%ADculo_45_1_11.pdf

Female and male specimens of Doridicola similis Ho and Kim, 2001 (Copepoda: Poecilostomatoida: Rhynchomolgidae) from the gills of the loliginid squid Sepioteuthis sp. (called shiro-ika) (Cephalopoda: Myopsida: Loliginidae) in coastal Pacific waters of central Japan are described as a new country record. This collection represents the second record of D. similis and expands its distribution range from the Gulf of Thailand (type locality) northeast to the western North Pacific Ocean off central Japan.

Cephalopods in nature undergo highly dynamic skin coloration changes that allow rapid camouflage and intraspecies communication. The optic lobe is thought to play a key role in controlling the expansion of the chromatophores that generate these diverse body patterns. However, the functional organization of the optic lobe and neural control of the various body patterns by the optic lobe are largely unknown. We applied electrical stimulation within the optic lobe to investigate the neural basis of body patterning in the oval squid,Sepioteuthis lessoniana. Most areas in the optic lobe mediated predominately ipsilateral expansion of chromatophores present on the mantle, but not on the head and arms; furthermore, the expanded areas after electrical stimulation were positively correlated with an increase in stimulating voltage and stimulation depth. These results suggest a unilaterally dominant and vertically converged organization of the optic lobe. Furthermore, analyzing 14 of the elicited body pattern components and their corresponding stimulation sites revealed that the same components can be elicited by stimulating different parts of the optic lobe and that various subsets of these components can be coactivated by stimulating the same area. These findings suggest that many body pattern components may have multiple motor units in the optic lobe and that these are organized in a mosaic manner. The multiplicity associated with the nature of the neural controls of these components in the cephalopod brain thus reflects the versatility of the individual components during the generation of diverse body patterns.SIGNIFICANCE STATEMENTNeural control of the dynamic body patterning of cephalopods for camouflage and intraspecies communication is a fascinating research topic. Previous studies have shown that the optic lobe is the motor command center for dynamic body patterning. However, little is known about its neural organization and the mechanisms underlying its control of body pattern generation. By electrically stimulating the optic lobe of the oval squids and observing their body pattern changes, surprisingly, we found that there is no somatotopic organization of motor units. Instead, many of these components have multiple motor units within the optic lobe and are organized in a mosaic manner. The present work reveals a novel neural control of dynamic body patterning for communication in cephalopods.

The use of mass-marking techniques of enriched stable isotopes has increased in studies of ecology, movement patterns and the dispersal of marine organisms. However, the efficacy of this technique and its potential effects on hatchling size and statolith chemistry of cephalopods are yet to be investigated. Sepioteuthis lessoniana egg capsules were collected from northern Taiwan and assigned randomly to 137Ba-spiking experimental groups at 0.2, 0.5 and 1ppm and three immersion durations (1, 3 and 7 days). Immersion duration >3 days produced significantly lower 138Ba:137Ba ratios, with 100% marking success, indicating that it is a reliable marking technique. The 137Ba mass marking had a positive effect on size at hatch and was likely to affect statolith trace element incorporation, including Cu, Zn and Pb. These findings highlight that it is necessary to consider the species-specific effects on hatchling size and physiological responses in when using stable isotopes mass-marking techniques.

Anthropogenic carbon dioxide (CO2) emissions are being absorbed by the oceans, a process known as ocean acidification, and risks adversely affecting a variety of behaviours in a range of marine species, including inhibited learning in some fishes. However, the effects of elevated CO2on learning in advanced invertebrates such as cephalopods are unknown. Any impacts to the learning abilities of cephalopods could have far-reaching consequences for their populations and the communities they inhabit. Cephalopods have some of the most advanced cognitive abilities among invertebrates and are one of the few invertebrate taxa in which conditional discrimination has been demonstrated, though the trait has not been demonstrated in any species of squid. Here, we tested for the first time the capacity for conditional discrimination in a squid species (Sepioteuthis lessoniana). Furthermore, we investigated the effects of projected future CO2levels (1,084 µatm) on conditional discrimination and learning more generally. A three-task experiment within a two-choice arena was used to test learning and conditional discrimination. Learning was measured by improvements in task completion in repeated trials over time and the number of trials required to pass each task. Squid exhibited significant learning capabilities, with an increase in correct choices over successive trials and a decrease in the number of trials needed to complete the successive tasks. Six of the 12 squid tested successfully passed all three tasks indicating a capacity for conditional discrimination in the species. Elevated CO2had no effect on learning or on the capacity for conditional discrimination in squid. This study highlights the remarkable cognitive abilities ofS. lessoniana, demonstrated by their capacity for conditional discrimination, and suggests that ocean acidification will not compromise learning abilities. However, other behavioural traits in the species have been shown to be altered at comparable elevated CO2conditions. It is not clear why some ecologically important behaviours are altered by elevated CO2whereas others are unaffected. Future research should focus on the physiological mechanism responsible for altered behaviours in squid at elevated CO2.

The wide disparity in adult body size observed both within and among animal taxa has long attracted widespread interest, with several general rules having been proposed to explain trends in body size evolution. Adult body size disparity among the cephalopod mollusks is remarkable, with adult body sizes ranging from a few centimeters to several meters. Some of the smallest cephalopods are found within Pickfordiateuthis, a group comprising three described species of squid found in the western Atlantic and tropical eastern Pacific. Pickfordiateuthis pulchella, the type species of the genus, was initially proposed to be closely related to the loliginid squids (Loliginidae), with subsequent descriptions of additional species supporting a placement within Loliginidae. Pickfordiateuthis is remarkable in that all species reach sexual maturity at about one-fifth to one-tenth the size seen in most loliginid species. To date, no phylogenetic analyses have included representatives of Pickfordiateuthis. To infer the phylogenetic position of Pickfordiateuthis and explore its implications for body size evolution, we collected specimens of Pickfordiateuthis pulchella from Brazilian waters and sequenced regions of two loci—the mitochondrial large ribosomal subunit (rrnL a.k.a. 16S) gene and the nuclear gene rhodopsin. Maximum likelihood and Bayesian analyses of these sequences support a placement of Pickfordiateuthis pulchella as sister to a clade comprising the Western Hemisphere loliginid genera Doryteuthis and Lolliguncula. Analyses of body size evolution within Loliginidae suggest that a shift to a smaller body size optimum occurred along the lineage leading to P. pulchella, with some evidence of shifts toward larger sizes in the ancestors of Loligo and Sepioteuthis; these inferences seem to be robust to phylogenetic uncertainty and incomplete taxon sampling. The small size and juvenile-like morphological traits seen in adult Pickfordiateuthis (e.g., sepiolid-like fins and biserial sucker arrangement in the tentacles) may be due to paedomorphosis.

Long-term exposure to projected future CO2 levels has no effect on the aerobic performance of two tropical cephalopod species. The resting oxygen uptake rates, maximal oxygen uptake rates, aerobic scope, and recovery time of both bigfin reef squid and two-toned pygmy squid were unaltered by elevated CO2., Squid and many other cephalopods live continuously on the threshold of their environmental oxygen limitations. If the abilities of squid to effectively take up oxygen are negatively affected by projected future carbon dioxide (CO2) levels in ways similar to those demonstrated in some fish and invertebrates, it could affect the success of squid in future oceans. While there is evidence that acute exposure to elevated CO2 has adverse effects on cephalopod respiratory performance, no studies have investigated this in an adult cephalopod after relatively prolonged exposure to elevated CO2 or determined any effects on aerobic scope. Here, we tested the effects of prolonged exposure (≥20% of lifespan) to elevated CO2 levels (~1000 μatm) on the routine and maximal oxygen uptake rates, aerobic scope and recovery time of two tropical cephalopod species, the two-toned pygmy squid, Idiosepius pygmaeus and the bigfin reef squid, Sepioteuthis lessoniana. Neither species exhibited evidence of altered aerobic performance after exposure to elevated CO2 when compared to individuals held at control conditions. The recovery time of I. pygmaeus under both control and elevated CO2 conditions was less than 1 hour, whereas S. lessoniana required approximately 8 hours to recover fully following maximal aerobic performance. This difference in recovery time may be due to the more sedentary behaviours of I. pygmaeus. The ability of these two cephalopod species to cope with prolonged exposure to elevated CO2 without detriment to their aerobic performance suggests some resilience to an increasingly high CO2 world.

Unlike vitellogenin, which is the sole major precursor of yolk protein in all oviparous vertebrates, a variety of major precursor of yolk proteins are found among oviparous invertebrates. Sea urchins have a transferrin-like yolk protein, while all other major precursors of yolk proteins in oviparous invertebrates belong to the superfamily of large lipid transfer proteins (LLTPs). However, a comprehensive understanding of vitellogenesis is absent in cephalopods. To understand control of vitellogenesis by the LLTPs gene, two vitellogenins (VTG1 and VTG2), two apolipophorins (APOLP2A and APOLP2B), and a cytosolic large subunit of microsomal triglyceride transfer protein (MTTP) found in the bigfin reef squid. Only the two VTGs showed high levels of expression in mature females compared to males.We further analyzed the expression profile and localization of both VTGs/VTGs during ovarian development. Our data showed that VTGs/VTGs expressions were correlated to the female reproductive cycle. Ovarian VTG1 and VTG2 were localized in the follicle cells but not in oocytes. In addition, VTG1 and VTG2 were represented in follicle cells and oocytes. Thus, our results showed that both VTGs were synthesized by follicle cells and are then delivered to oocytes. In addition, we demonstrated that VTGs were the major precursor of yolk protein in bigfin reef squid. We also found differential proteolytic cleavage processes of VTG1 and VTG2 during VTGs accumulation in oocytes. Therefore, our data shed light on the molecular mechanism of the yolk accumulation pathway in cephalopods.Summary SentenceTwo distinct vitellogenins, which are synthesized by the follicle cells, are the major precursor of yolk protein of oocytes in bigfin reef squid.

Cephalopods use a diverse range of body patterns for visual communication. Each pattern is composed of several distinct chromatic components that are under neural control and are expressed dynamically. In the oval squid Sepioteuthis lessoniana, males use distinct body patterns to interact with females and other males at the spawning site. To systematically examine their visual signals during reproductive behavior, an ethogram of 27 body pattern components produced by S. lessoniana was observed in both the wild and captivity; these were then characterized. Five behaviors were commonly seen among these reproductively active squids, namely parallel swimming, male guarding, male-male fighting, male-parallel mating, and male-upturn mating. Each behavior was found to be composed of the expression in a temporal sequence of different chromatic components. By analyzing the dynamic body patterning time series associated with each behavior, it was found that a certain subset of components was expressed simultaneously or sequentially in response to conspecifics. Importantly, the results not only revealed that each behavior is composed of multiple chromatic components, but the findings also showed that each component is often associated with multiple behaviors. To gain insight into the visual communication associated with each behavior in terms of the body patterning's key components, the co-expression frequencies of two or more components at any moment in time were calculated in order to assess uniqueness when distinguishing one behavior from another. This approach identified the minimum set of key components that, when expressed together, represents an unequivocal visual communication signal. While the interpretation of the signal and the associated response of the receiver during visual communication are difficult to determine, the concept of the component assembly is similar to a typical language within which individual words often have multiple meanings, but when they appeared together with other words, the message becomes unequivocal. The present study thus demonstrates that dynamic body pattering, by expressing unique sets of key components acutely, is an efficient way of communicating behavioral information between oval squids.

The big-fin reef squid, Sepioteuthis cf. lessoniana (Lesson 1930), is an important commodity species within artisanal and near-shore fisheries in the Indian and Indo-Pacific regions. While there has been some genetic and physical evidence that supports the existence of a species complex within S. cf. lessoniana, these studies have been extremely limited in scope geographically. To clarify the extent of cryptic diversity within S. cf. lessoniana, this study examines phylogenetic relationships using mitochondrial genes (cytochrome oxidase c, 16s ribosomal RNA) and nuclear genes (rhodopsin, octopine dehydrogenase) from nearly 400 individuals sampled from throughout the Indian, Indo-Pacific, and Pacific Ocean portions of the range of this species. Phylogenetic analyses using maximum likelihood methods and Bayesian inference identified three distinct lineages with no clear geographic delineations or morphological discriminations. Phylogeographic structure analysis showed high levels of genetic connectivity in the most widespread lineage, lineage C and low levels of connectivity in lineage B. This study provides significant phylogenetic evidence for cryptic lineages within this complex and confirms that cryptic lineages of S. cf. lessoniana occur in sympatry at both small and large spatial scales. Furthermore, it suggests that two closely related co-occurring cryptic lineages have pronounced differences in population structure, implying that underlying differences in ecology and/or life history may facilitate co-occurrence. Further studies are needed to assess the range and extent of cryptic speciation throughout the distribution of this complex. This information is extremely useful as a starting point for future studies exploring the evolution of diversity within Sepioteuthis and can be used to guide fisheries management efforts.

The oval squid Sepioteuthis lessoniana is one of the most economically important squid species in Japan; however, its population structure is poorly understood due to the lack of hypervariable markers. Such information is critical for managing sustainable fisheries, as well as for ensuring the existence of wild S. lessoniana stocks. Eleven candidate microsatellite loci were isolated from a small insert genomic DNA library. Polymorphisms in these 11 loci were screened in 24 wild individuals. The number of alleles per locus was found to range from 5 to 19 alleles, and the observed heterozygosity ranged from 0.292 to 0.958. No evidence for linkage disequilibrium was detected among all the loci. The genotypic proportions conformed to Hardy-Weinberg equilibrium, except at one locus. In conclusion, these polymorphic microsatellite loci may be used to develop a genetic framework to manage S. lessoniana in the future.

Coleoid cephalopods (squid, cuttlefish, and octopus) have the largest and most complex brains of all invertebrates and show behavioral abilities similar to those of vertebrates. Among the coleoids, the oval squid Sepioteuthis lessoniana forms well-structured schools that are indicative of sociality. These behaviors are re flected in aspects of the well-developed brain. In this study, we focused on the role of the cephalopod brain in complex behavior. In order to reveal the network of γ-aminobutyric acid (GABA) in coleoids, we examined the immunohistochemical localization of glutamic acid decarboxylase (GAD), which is the synthetic enzyme of GABA, in the brain of young S. lessoniana. We found that GABAergic neurons and their axons were distributed throughout the brain. GABA neurons were abundantly localized in the inferior frontal lobe, which is involved in controlling arm motions, and in the subesophageal masses, which are lower and intermediate centers of action. GABAergic fibers were abundantly localized in the tract that runs from the superior frontal lobe to the vertical lobe. These results sug- gested the involvement of GABA in both cognitive behaviors (such as learning and memory) and in movement.

A total of 25 mature female Sepioteuthis lessoniana (Lesson, 1830) specimens, with a dorsal mantle length between 120-196 mm, were investigated. Estimated potential fecundity varied from 180 to 1054 eggs with mean value of 497 eggs. The potential fecundity values of S. lessoniana in the Mandapam waters (Palk Bay) are found almost similar to those found in Tanzanian waters but higher than the ones in Sri Lankan lagoons. Larger females have higher potential fecundity. The correlation values showed that the fecundity is more closely related to the ovary weight and body weight than to the mantle length. Fecundity increased exponentially with mantle length. The Nidamental gland weight was also found more closely related to the ovary weight in logarithmic relationship. Fecundity vs. ovary weight (r = 0.899) and Nidamental gland weight vs. ovary weight (r = 0.942) exhibited a strong relationships while fecundity showed week correlations with mantle length (r = 0.658) and body weight (r = 0.663).

Some aspects of the reproductive characteristics of the commercially important squid Sepioteuthis lessoniana (Lesson, 1830) in the coastal waters of Mandapam, Palk Bay was studied with a view to provide possible management measures in this region. A total of 984 individuals (508 males and 476 females) were collected between April, 2009 to March, 2010. The size of specimens ranged from 40 mm to 290 mm in mantle length. Sex ratio was not significantly different from the expected ratio of 1:1 except for months of July, October and December. Spawning season as revealed by seasonal maturity stages, gonadosomatic index of sexes and nidamental gland length (NGL) and dorsal mantle length (DML) ratio of females, lied between January to June with peak at February. Size at maturity as determined by graphical method was 83.5 for males and 112.5 for females.

In the present study, the impact of cadmium on embryonic development, morphology of eggs and newly hatched larvae of the Sepioteuthis lessoniana were described using the laboratory-reared specimens originating from Thondi, South East coast of India. The eggs were exposed to a concentration of 25 μg Cd/L for up to hatching. The average incubation period of the eggs varied between 18-23 days and the estimated mean temperatures were 18.6 ± 0.7°C for control, and 19.2 ± 1.1°C for Cd exposed groups. The results revealed that a total hatching rate of 99.2 ± 1.6% was achieved in control group and only 65.2 ± 8.8% in treated group. The deformities of the paralarvae were illustrated with light and scanning electron microscopy. In conclusion, the present concentration exhibited toxic effects to the eggs and paralarvae of S. lessoniana. Therefore, Cd level as high as we used in this study could give good information on dangerous Cd levels on squid.

Antipredator responses, especially those of open-ocean squid, have been seldom studied in the natural environment. Sepioteuthis sepioidea, observed by snorkellers near the shore in early morning/late afternoon, produced an average of eight moves of over 1 m per hour, apparently mostly antipredator behaviours. Close approaches by herbivorous parrotfish elicited no response in 74% of encounters; otherwise, squid produced agonistic zebra stripes or startle-mantle-dots skin patterns. Predatory bar jack fish caused flight but not zebra displays, and squid usually paled and fled quickly (66%) from snapper. The speed of approach was the best predictor for flight and display responses to snapper, but for bar jack and parrotfish, the relative fish size and distance were the predictors for escalated responses. Paired dorsolateral mantle dots were produced when squid approached the sea bottom or hunted outside the group and in reaction to fish approaches; 56% of these were to the very common parrotfish. Reactive pai...

Genetic diversity and population structure of Japanese populations of the oval squid, Sepioteuthis cf. lessoniana, were compared with populations from Taiwan and Vietnam using nucleotide sequences of the mitochondrial DNA non-coding region 2. In total, 402 nucleotide sequences representing 242 individuals from Japanese waters (Ishikawa, Japan Sea coast of Honshu; Tokushima, eastern Shikoku; Nagasaki, western Kyushu; and Okinawajima and Ishigakijima Island, in the Ryukyu Archipelago) and the East and South China Seas (Keelung, northern Taiwan; Vietnam, Gulf of Tonkin) were examined. Among the 29 haplotypes recognized, haplotype no. 1 was shared by more than 75% of individuals from Japanese localities, whereas it was found in less than 13% of specimens from the East and South China Seas populations. Conversely, the East and South China Seas populations included more than 30% individuals with haplotype no. 2, whereas less than 10% of haplotype no. 2 individuals were from Japanese localities. The differences of haplotype and nucleotide diversities between pooled Japanese populations (0.2639, 0.23%) and the East and South China Seas populations (0.7900, 1.01%) indicate that S. cf. lessoniana from Japanese waters exhibits lower genetic diversity. An analysis of molecular variance between the Japanese populations and the East and South China Seas populations was highly significant. A minimum spanning tree of 29 haplotypes and an Unweighted Pair Group Method with Arithmetic mean (UPGMA) tree based on pairwise F ST comparisons also supported the separation between Japanese and the East and South China Seas populations. We suggest that the Kuroshio Current physically limits gene flow and has thus caused the differences in genetic diversity among the populations examined.

Jackson, G. D., Meekan, M. G., Wotherspoon, S., and Jackson, C. H. 2008. Distributions of young cephalopods in the tropical waters of Western Australia over two consecutive summers. – ICES Journal of Marine Science, 65: 140–147. Cephalopod paralarvae and juveniles were sampled with light traps deployed at the surface and deeper in the southern NW Shelf and on Ningaloo Reef off Western Australia during two consecutive summers. One cross shelf transect (Exmouth) was sampled in the late spring and summers of 1997/1998 (summer 1) and 1998/1999 (summer 2), and a second cross shelf transect (Thevenard) and a longshore transect (Ningaloo) along the Ningaloo Reef were sampled in summer 2. Species captured in the order of abundance were octopods, Photololigo sp., Sepioteuthis lessoniana, and Sthenoteuthis oualaniensis. Most were captured in shallow traps except for Photololigo sp., which was common in both shallow and deep traps with larger animals found in deeper water. The presence of Idiosepius pygmaeus in deep water off Ningaloo Reef revealed the species to be eurytopic, inhabiting a wider range of habitats than previously known. Photololigo sp. and S. lessoniana were more abundant inshore, and octopods were especially abundant on mid-depth stations of the Exmouth transect, probably because of the turbulent mixing and increased productivity there. Fewer S. oualaniensis were caught during the first summer on the Ningaloo transect (n = 5) than during the second summer (n = 79).

アオリイカ死後の鮮度変化と外套筋の白濁について検討した。試料を即殺後，外套筋を氷蔵，5，10，15℃ の各温度で保存し，ATP 関連化合物，グリコーゲン，pH および L*値を経時的に測定した。ATP 量の減少は氷蔵≒5℃>15℃>10℃ の順であった。グリコーゲン含量は氷蔵より 10℃ の方が緩やかに減少した。pH は明瞭な変化が見られなかった。外套筋が明らかに白濁した L*値 50 を越える保存時間は 10℃ が 12 時間で最も遅く ATP 量の減少と同傾向であった。

CO2 ocean storage is proposed as a possible measure to mitigate climate changes caused by increasing atmospheric concentrations of the gas. The feasibility of the measure has been intensively investigated, yet its biological impact on marine animals is still largely unknown. We investigated the acute CO2 tolerance of juveniles of three marine invertebrates; the cuttlefish, Sepia lycidas, the squid, Sepioteuthis lessoniana, and the prawn, Marsupenaeus japonicus. Median tolerance limits of CO2 were 8.4% (24 h) for the cuttlefish, 5.9% (24 h) and 3.8% (48 h) for the squid and 14.3% (72 h) for the prawn. Comparison of these and previously reported data suggests an inverse relationship between O2 requirement and CO2 tolerance among marine animals., Plankton and Benthos Research, 3(3), pp.184-187; 2008

The use of temporal and/or spatial fish- ing exclusions is a common approach in managing impacts of squid fisheries targeting spawning aggre- gations, although there are limited data for assessing closed areas as a management tool. We evaluated the degree of protection that 2 closed areas were providing to individual spawning Sepioteuthis aus- tralis and assessed the extent of exchange between these coastal regions, separated by only 25 to 32 km. VR2 acoustic receivers were placed along the bound- aries of closed areas on the east coast of Tasmania, Australia, across smaller bays within these areas, and on individual seagrass beds. Over 77 000 detection events were obtained from 46 individuals over dura- tions of up to 129 d, demonstrating that individuals spawn over several months, traveling 100s of km within the spawning areas during this time. Squid were detected at closed area boundaries; however, most were detected again on other receivers within the closed area, indicating that although squid had moved within boundary vicinities, they had not actually left the protected area. Closures of critical spawning regions during times of heightened repro- ductive activity will therefore achieve the desired effect of protecting spawners and will allow for egg- laying. Clearly, inshore squid species can be highly mobile during an extended spawning phase and any assessment of the management benefits of closed areas needs to explicitly consider the temporal and spatial scales of the closed area in question.

We examined the relationship between mantle muscle structure and mantle kinematics in an ontogenetic series (5-85 mm dorsal mantle length) of oval squid, Sepioteuthis lessoniana. Thick filament length increased during growth in the mantle muscle fibres that power jet locomotion (i.e. the circular muscles). The thick filament length of both the superficial mitochondria-rich (SMR; analogous to vertebrate red muscle fibres) and central mitochondria-poor (CMP; analogous to vertebrate white muscle fibres) circular muscles increased significantly during ontogeny. Thick filaments in the SMR circular muscle fibres of newly hatched squid (N=5) ranged from 0.7 to 1.4 microm and averaged 1.0 microm, while the thick filaments of the SMR fibres of the largest squids (N=4) studied ranged from 1.2 to 3.4 microm and averaged 1.9 microm. The ontogeny of thick filament length in the CMP circular muscle fibres showed a similar trend. The range for hatchling CMP circular muscles was 0.7-1.4 microm, with an average of 1.0 microm, whereas the range and average for the largest squids studied were 0.9-2.2 microm and 1.5 microm, respectively. Within an individual hatchling, we noted no significant differences between the thick filament lengths of the SMR and CMP fibres. Within an individual juvenile, the thick filaments of the SMR fibres were approximately 25% longer than the CMP fibres. The change in thick filament length may alter the contractile properties of the circular muscles and may also result in a decrease in the rate of mantle contraction during jetting. In escape-jet locomotion, the maximum rate of mantle contraction was highest in newly hatched squid and declined during ontogeny. The maximum rate of mantle contraction varied from 7-13 muscle lengths per second in newly hatched squid (N=14) and from 3-5 muscle lengths per second in the largest squids (N=35) studied.

Allozyme electrophoresis was used to investigate the taxonomic status of northern calamary Sepioteuthis lessoniana (Lesson 1830) from two sites in Shark Bay, Western Australia. Of the 40 squid examined at 38 presumptive loci, four individuals from the oceanic site were clearly differentiated from the rest by fixed allelic differences at four loci (Acp, Got2, Idh2, and PepD) and near-fixed differences at another three (Est, Ocdh, and 6Pgd). The genetic distances between these two groups of individuals (13% Fixed Differences and Nei, D (1978) = 0.178) were roughly twofold greater than those between the two cryptic taxa in the southern calamary S. australis, but are considerably smaller than those between the northern and southern calamary. The most likely explanation for these data is that S. lessoniana comprises two “cryptic” biological species in this region. Further studies are needed to delineate the total number of species found throughout Australasia for this important loliginid squid.

The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set net were 85.3 and 11.3 mm, respectively. In the trammel net fishery where oval squid are herded into the net, most of the oval squid are caught in the bag-shaped inner net. Hence, the logistic function was employed for the size selectivity curve of the trammel net. The ‘share each length's catch total’ (SELECT) model was implemented for the estimation of the selectivity curve. The size selectivity r(l) of the trammel net for the oval squid was expressed as a logistic function of the mantle length l: r(l) = exp(−18.57 + 0.88 l)/[1 + exp(−18.57 + 0.88 l)]. From these logistic parameter estimates, the 50% selection mantle length and selection range (L75–L25) were calculated as 21.07 and 2.49 cm, respectively. The selection probability of oval squid whose mantle girth was equivalent to the mesh perimeter of the inner net was 0.09. Accordingly, oval squid of a girth smaller than the mesh perimeter were likely to pass through the mesh to escape from the net.

Fish catch by a set net in Hamdeuk fishing ground off Jeju Island were studied to determine seasonal variation of species composition and catch from 1998 to 2000. A total 72,022.9 kg was caught during the survey period, including Scomber japonicus and Trachurus japonicus of in the total. The other dominant species were Siganus fuscescens, Loligo chinesis, Seriola dumerili, Sepioteuthis lessoniana, Sardinops melanostictus, and Seriola lalandi accounting to of the total. The fishing period conducted by a set net in Hamdeuk fishing ground were from May to November. The catch by a set net were higher in summer than in spring and autumn and closely related with the seasonal variation of sea water temperature. The catch was higher in 1998 than In 1999 and 2000, which was related to the sea water temperature in fishing ground.

Predation by invertebrates may be one of the major factors influencing the mortality of released flounder juveniles in the field. We developed a polymerase chain reaction (PCR)-based technique for the detection of Japanese flounder material from the gut contents of potential predators in the field. The PCR primers used here are flounder specific and encompass a 153 bp region from the right domain of the mitochondrial control region. With these oligonucleotide primers, PCR reactions yielded specific amplification products from the gut contents of some putative predators, including Matuta lunaris, Portunus gladiator, Sepioteuthis lessoniana, Suggrundus meerdervoorti, Platycephalus sp. and Rhyncopelates oxyrhynchus. Many animals with gut contents of unidentified fish material showed indication of predation on the flounder after release of hatchery reared flounder juveniles. The technique developed in the present study is useful not only for the survey of predation on the flounder by known species, but also for the search for novel potential predatory species in the field.

In Sepioteuthis lessoniana, the oval squid, on- togenetic changes in the kinematics of the mantle during escape-jet locomotion imply a decline in the relative mass flux of the escape jet and may affect the peak weight- specific thrust of the escape jet. To examine the relationship between ontogenetic changes in the kinematics of the man- tle and the thrust generated during the escape jet, we simul- taneously measured the peak thrust and the kinematics of the mantle of squid tethered to a force transducer. We tested an ontogenetic series of S. lessoniana that ranged in size from 5 to 40 mm dorsal mantle length (DML). In newly hatched squids, thrust peaked 40 ms after the start of the escape jet and reached a maximum of between 0.10 mN and 0.80 mN. In the largest animals, thrust peaked 70 ms after the start of the escape jet and reached a maximum of between 18 mN and 110 mN. Peak thrust was normalized by the wet weight of the squid and also by the cross-sectional area of the circumferential muscle that provides power for the escape jet. The weight-specific peak thrust of the escape jet averaged 0.36 in newly hatched squid and increased significantly to an average of 1.5 in the largest squids measured (P 0.01). The thrust per unit area of circum- ferential muscle averaged 0.25 mN/mm 2 in hatchlings and increased significantly to an average of 1.4 mN/mm 2 in the largest animals tested ( P 0.01). The impulse of the escape jet was also lowest in newly hatched individuals (1.3 mN s) and increased significantly to 1000 mN si n the largest squids measured (P 0.01). These ontogenetic changes in the mechanics of the escape jet suggest (1) that propulsion efficiency of the exhalant phase of the jet is highest in hatchlings, and (2) that the mechanics of the circumferential muscles of the mantle change during growth.

Giant squids ( Architeuthis ) are a legendary species among the cephalopods. They live in the deep sea and are well known for their enormous body and giant eyes. It has been suggested that their giant eyes are not adapted for the detection of either mates or prey at distance, but rather are best suited for monitoring very large predators, such as sperm whales, at distances exceeding 120 m and at a depth below 600 m (Nilsson et al. 2012 Curr. Biol. 22 , 683–688. ( doi:10.1016/j.cub.2012.02.031 )). However, it is not clear how the brain of giant squids processes visual information. In this study, the optic lobe of a giant squid ( Architeuthis dux , male, mantle length 89 cm), which was caught by local fishermen off the northeastern coast of Taiwan, was scanned using high-resolution magnetic resonance imaging in order to examine its internal structure. It was evident that the volume ratio of the optic lobe to the eye in the giant squid is much smaller than that in the oval squid ( Sepioteuthis lessoniana ) and the cuttlefish ( Sepia pharaonis ). Furthermore, the cell density in the cortex of the optic lobe is significantly higher in the giant squid than in oval squids and cuttlefish, with the relative thickness of the cortex being much larger in Architeuthis optic lobe than in cuttlefish. This indicates that the relative size of the medulla of the optic lobe in the giant squid is disproportionally smaller compared with these two cephalopod species. This morphological study of the giant squid brain, though limited only to the optic lobe, provides the first evidence to support that the optic lobe cortex, the visual information processing area in cephalopods, is well developed in the giant squid. In comparison, the optic lobe medulla, the visuomotor integration centre in cephalopods, is much less developed in the giant squid than other species. This finding suggests that, despite the giant eye and a full-fledged cortex within the optic lobe, the brain of giant squids has not evolved proportionally in terms of performing complex tasks compared with shallow-water cephalopod species.

Background: Cephalopods have evolved strong acid–base regulatory abilities to cope with CO2 induced pH fluctuations in their extracellular compartments to protect gas transport via highly pH sensitive hemocyanins. To date, the mechanistic basis of branchial acid–base regulation in cephalopods is still poorly understood, and associated energetic limitations may represent a critical factor in high power squids during prolonged exposure to seawater acidification. Results: The present work used adult squid Sepioteuthis lessoniana to investigate the effects of short-term (few hours) to medium-term (up to 168 h) seawater acidification on pelagic squids. Routine metabolic rates, NH4 + excretion, extracellular acid–base balance were monitored during exposure to control (pH 8.1) and acidified conditions of pH 7.7 and 7.3 along a period of 168 h. Metabolic rates were significantly depressed by 40% after exposure to pH 7.3 conditions for 168 h. Animals fully restored extracellular pH accompanied by an increase in blood HCO3 � levels within 20 hours. This compensation reaction was accompanied by increased transcript abundance of branchial acid–base transporters including V-type H + -ATPase (VHA), Rhesus protein (RhP), Na + /HCO3 � cotransporter (NBC) and cytosolic carbonic anhydrase (CAc). Immunocytochemistry demonstrated the sub-cellular localization of Na + /K + -ATPase (NKA), VHA in basolateral and Na + /H + -exchanger 3 (NHE3) and RhP in apical membranes of the ion-transporting branchial epithelium. Branchial VHA and RhP responded with increased mRNA and protein levels in response to acidified conditions indicating the importance of active NH4 transport to mediate acid–base balance in cephalopods. Conclusion: The present work demonstrated that cephalopods have a well developed branchial acid–base regulatory machinery. However, pelagic squids that evolved a lifestyle at the edge of energetic limits are probably more sensitive to prolonged exposure to acidified conditions compared to their more sluggish relatives including cuttlefish and octopods.

Muchlisin ZA, Zulkarnaini B, Purnawan S, Muhadjier A, Fadli N, Cheng SH. 2014. Morphometric variations of three species of harvested cephalopods found in northern sea of Aceh Province, Indonesia. Biodiversitas 15: 142-146. The purpose of the present studywas to evaluate the morphometrics of three harvested cephalopods, Sepioteuthis lessoniana, Sepia officinalis and Uroteuthis sp. found innorthern sea of Aceh Province, Indonesia. Sampling was conducted for six months from July to December 2012 in one week interval. Atotal of 318 cephalopods; 139 Sepioteuthis lessoniana, 139 Uroteuthis sp. and 40 Sepia officinalis were analyzed for morphometricstudy and 13 anatomical characters were measured to the nearest 0.01 mm using a digital caliper. Morphometric measurements weresignificantly different between the different species of cephalopods (ANOVA, p

The phylogenetic relationships among the loliginid squids, a species-rich group of shallow-water muscular squids, have been investigated recently using several approaches, including allozyme electrophoresis and analyses of morphological and DNA sequence data, yet no consensus has been reached. This study examines the effects of combining multiple data sets (morphology, allozymes and DNA sequence data from two mitochondrial genes) on estimates of loliginid phylogeny. Various data combinations were analysed under three maximum parsimony weighting schemes: equal weights for all characters, successive approximations and implicit weights parsimony. When feasible, support for branches within trees was assessed with nonparametric bootstrapping and decay analysis. Some ingroup relationships were consistent across all analyses, but relationships among outgroup taxa and basal ingroup taxa varied. Combining data increased bootstrap support for several nodes. Methods that downweight highly variable characters (i.e. successive approximations and implicit weights parsimony) produced very similar trees which included two major clades: a clade consisting of all species sampled from American waters (except Sepioteuthis ), and a clade of several east Atlantic species ( Loligo forbesi Steenstrup, Loligo vulgaris Lamarck and Loligo reynaudi d»Orbigny) plus several Indo-West Pacific species in the genera Uroteuthis and Loliolus . The Sepioteuthis species occupied a basal position within Loliginidae, but Sepioteuthis itself was not always monophyletic. The position of a clade of a few Lolliguncula species and Loligo ( Alloteuthis ) also varied across analyses. A new loliginid classification is proposed based on these findings.

epioteuthis lessoniana Lesson, 1830, represents the most common species of squids in the Red Sea. It was chosen for a detailed study of the macro- and microscopic anatomy of its male reproductive system with special reference to the structure of its spermatophores and the method of their formation. The male reproductive system is differentiated into a single testis and a gonoduct which consists of a vas deferens, a complex spermatophoric organ, a spermatophoric duct and a spermatophoric sac that ends with a muscular conducting tube. The testis is formed of a large number of closely compact seminiferous tubules containing different stages of spermatogenesis. The spermatophoric organ is composed of six glands: mucilagenous I & n, ejaculatory appartaus, middle and outer tunic and accessory gland with its appendix. The structure of each of these glands was demonstrated and discussed. The spermatophore of S. lessoniana is a minute structure that consists of a spermatophoric cord and an ejaculatory apparatus connected together through the connective region. The structure of different parts of the spermatophore and the method of their formation were studied and discussed. s

A vasoactive intestinal peptide (VIP)-like peptide is released by axonal stimulation in the giant axon–Schwann cell preparation from the tropical squid Sepioteuthis sepioidea. It is also released by direct application of L-glutamate, the giant axon–Schwann cell signalling molecule in this preparation. The release of the peptide parallels the release of acetylcholine from the Schwann cells themselves in this preparation in a number of different ways. The release of both acetylcholine and the VIP-like peptide have the same threshold (between 2×10−10 and 5×10−10 mol l−1) for L-glutamate application and the same recovery time after inhibition of release by exposure of the preparation to a prolonged pulse of L-glutamate. A prolonged L-glutamate pulse of 10−8 mol l−1 releases both substances for as long as the pulse is applied to the preparation, whereas a prolonged pulse of 10−9 mol l−1 L-glutamate releases acetylcholine in the same way but releases the VIP-like peptide only transiently. The VIP-like peptide is likely to be co-released with acetylcholine from the Schwann cells.