Male Squid Research Articles

Males conditionally inseminate at three female body locations according to female mating history and female maturity status in a squid.

In some squids, such as those in the family Loliginidae, upon copulation, females receive and store male-delivered sperm capsules, spermatangia, at two different body locations: the buccal membrane and the distal end of the oviduct. This insemination site dimorphism is associated with alternative reproductive strategies. However, in Loliolus sumatrensis, a species of Loliginidae, the females possess three insemination sites: buccal membrane (BM), basal left IV arm (ARM) and lateral head behind the left eye (EYE), therefore we studied such the unusual phenomena. We developed microsatellite markers and genotyped the paternity of each spermatangium on three sites. We found multiple paternity at every single site and simultaneous usage of all three sites by a few males. The seasonal dynamics of a population in the Seto Inland Sea revealed a set priority for the initial use of insemination sites as BM, followed by ARM and then EYE, whereas the maximum number of stored spermatangia was greater in EYE > ARM > BM. Female maturity status was correlated with the usage pattern of insemination sites but not with the number of stored spermatangia at any insemination site. These results suggest that a male squid inseminates at different locations according to female mating history and female maturity status.

Biological aspects of squid (Loligo edulis) in the waters of Eastern North Sumatra, Indonesia

Squid is one of the non-fish resources that have economic value and is a target species in demersal fisheries activities with squid fishing gear and stick-held deep net. This research aims to determine the biological aspects of squid (Loligo edulis) such as length frequency distribution, length-weight relationship, sex ratio, gonadal maturity level, gonadal maturity index, size at first caught, and size at first maturity of the gonads. The method used in this research was a descriptive survey. The sample collection method used systematic random sampling and purposive sampling techniques. This observation was carried out on March 7 to July 30, 2022, at the Belawan Ocean Fishing Port and Tanjung Balai Port. The results showed that the average length distribution of squid was 17.73 cm. The relationship between the length and weight of squid is negative allometric. The sex ratio is 1:1.05. The negative allometric growth pattern is dominated by Gonadal Maturity Level (GML) I and GML II. The highest GML value for male squid was 2.06% at GML III, and the highest GML value for female squid was 1.92% at GML III. The average size of the caught squid length (Lc) is 10.42 cm. The size of the first gonad maturity (Lc) was 13.32 cm.Keywords:SquidBiological aspectsFisheries aspectManagement effort

Inter-annual variability in growth and maturation of the swordtip squid Uroteuthis edulis in Yilan Bay off northeastern Taiwan

The swordtip squid Uroteuthis edulis, distributed in the temperate and tropical neritic waters in the Indo-Pacific region, is a crucial component of marine ecosystems and is a target species of fisheries in the Northwest Pacific. Although studies have elucidated the growth and maturation of the squid in the southern East China Sea (ECS) shelf, few have assessed the population biology of the squid in waters in the vicinity of the southern ECS. We collected samples of swordtip squid from a trawler in Yilan Bay (YLB) between January 2011 and December 2012 to examine the growth and maturation of the squid based on statolith microstructures and the inter-annual variability in certain parameters as well as the potential underlying mechanisms. The average dorsal mantle length (ML) of the squid was significantly higher in 2011 than in 2012 in both sexes. The ML-body weight relationship differed significantly between 2011 and 2012 in both sexes. Squid hatching peaked in summer (June and August)in 2011 and spring (March and April) in 2012. The average ML-at-age data were described using the exponential function and power function for female and male squid, respectively. Female squid matured to 139 mm at 133 days in 2011 and to 133 mm at 137 days in 2012. Male squid matured to 160 mm at 151 days in 2011 and to 148 mm at 133 days in 2012. However, the ML- and age-at-maturity of the squid in YLB were lower than those of the squid in the southern ECS shelf. These results indicate that YLB is one of the feeding grounds for squid that have hatched in the southern ECS shelf and have been transported southward intermittently to YLB. Further study of the population structure and potential population connectivity of the squid in the entire ECS shelf is warranted to obtain data for the development of effective conservation and management measures for the squid and its fisheries in the Northwest Pacific.

Environmental influence on life-history traits in male squid Uroteuthis edulis with alternative reproductive tactics

Squid are characterized by flexible life-history traits (LHTs) that change in response to changing oceanic parameters. Male alternative reproductive tactics (ARTs), characterized by large-sized ‘consorts’ versus small-sized ‘sneakers’, are commonly observed in loliginid species. This study reports on LHTs flexibility in male squids displaying ARTs. LHTs of consorts and sneakers in Uroteuthis edulis, including body size, age, growth rate and gonado-somatic energy allocation, were compared among seasonal and geographical groups from Japan and Taiwan. The ratio of consorts to sneakers was highest in the group spawning in the ‘Japan-warm’ season (June–November), followed by that of the ‘Japan-cold’ season (December–May), and lowest in Taiwan (spring and autumn). LHTs were compared among cohorts separated by hatching season and catch location (Jwarm, Jcold and Taiwan cohorts). Mean body size of consorts showed no difference among cohorts, although Taiwan consorts were relatively younger than Japan consorts. Mean size and age of sneakers decreased with increased water temperature at hatching. Growth rates of consorts and sneakers were slightly different among cohorts, in accordance with differences of statolith increment widths during their early life stage (50–150 days). Growth rates of both consorts and sneakers were highest in the Taiwan cohort, followed by the Jwarm cohort, with the Jcold cohort lowest. Sneakers invested more both in mantle and gonadal weights than consorts in all cohorts. Gonado-somatic energy allocation patterns of consorts and sneakers were consistent at different temperatures. LHTs of U. edulis consorts and sneakers were strongly influenced by temperature, with higher flexibility in sneakers than consorts.

Relationship between empirical water temperature and spring characteristics of swordtip squid (Uroteuthis edulis) caught in the eastern Tsushima Strait

ABSTRACTWe analysed the data of swordtip squid Uroteuthis edulis caught in the eastern Tsushima Strait, from April to September between 2012 and 2018, to consider the relationships among mantle length and body and gonad weights, associated with the estimated seasonal migratory routes and itineraries improved by the quantitative results of the tracer experiments. Our analyses have enabled us to reveal the characteristics of kensaki-type squid and the reasons for their appearance. We identified the kensaki-type U. edulis as male individuals, caught mainly in April–June, with long slender bodies, probably adapted to empirical duration of the cold sea water temperature in the Sea of Amakusa. Researchers and fishermen have referred to the seasonal migrating group including such males as a spring-migrating group. However, the females belonging to the spring-migrating group had no kensaki-type characteristics. Moreover, contrary to that achieved by the males, the female squid had acquired greater maturation in the spring than in any other seasons. These data demonstrated that the females continued to grow to maturation even in the cold sea waters, implying a different female strategy for reproduction from that of male squid. We are concerned that the commercially valuable kensaki-type squid may decrease in the future because the water temperature in the northern East China Sea is gradually rising, probably due to global climate change.

Population Dynamic of Squid (Loligo, sp) In the Banten Bay, Banten Province

Cumi-cumi (Loligo sp.) merupakan sumberdaya perikanan yang memiliki nilai ekonomis penting dan merupakan sumberdaya dengan produksi tertinggi kedua yang didaratkan di PPN Karangantu, Banten. Tujuan penelitian ini ialah mengkaji aspek dinamika populasi cumi-cumi (Loligo sp.) di perairan Teluk Banten. Pola pertumbuhan cumi-cumi betina dan jantan bersifat allometrik negatif. Panjang asimtotik (L∞) jantan lebih tinggi dari pada betina dengan nilai koefisien pertumbuhan (K) jantan dan betina sebesar 0,06 dan 0,16. Hasil analisis laju eksploitasi cumi- cumi di PPN Karangantu, Kota Serang, Banten telah melibihi laju eksploitasi optimum (0,5) sehingga secara biologi sumberdaya perikanan cumi-cumi diduga telah mengalami over eksploitasi.

The overlapping reproductive traits of the two male mating types of the oval squid Sepioteuthis lessoniana

The oval squid Sepioteuthis lessoniana is polyandrous, and a female mates with several males during a spawning season. This has resulted in two alternative male mating tactics in this species. The larger consort males usually use the male-parallel (MP) mating posture to put spermatophores at the opening of the oviduct; the smaller sneaker males predominantly use the male-upturned (MU) mating posture to place spermatophores around the female’s buccal membrane. Since squid eggs are released from the oviduct, MP mating is expected to have a higher fertilization rate than MU mating. Given the fact that these two male mating tactics are largely dependent on the body size of the male relative to the female, it is unclear how the smaller males are able to reproductively compete with the larger males. On analyzing spermatophore and sperm morphology from populations of adult male squids, spermatophore size was found to be positively correlated with mantle length of these squids, but sperm length was negatively correlated with squid mantle length. More importantly, no distinct size dimorphism exists in relation to either spermatophore morphology or sperm morphology. The overlap in size distributions of the spermatophores and sperms of the male squid thus implies that medium-sized males may have flexible reproductive strategies, switching between MP and MU mating tactics depending on the context of the mating event and/or female choice. This presumed behavioral plasticity might increase the reproductive success of these males and maintain the dynamic stability of two alternative mating types in this polyandrous species.

From sneaky to bully: reappraisal of male squid dimorphism indicates ontogenetic mating tactics and striking ejaculate transition

From sneaky to bully: reappraisal of male squid dimorphism indicates ontogenetic mating tactics and striking ejaculate transition

Female Choice Leads to a Switch in Oval Squid Male Mating Tactics.

Oval squids are polyandrous, with one female mating with multiple males during the spawning season. There are two alternative male mating tactics used by Sepioteuthis lessoniana. Larger males place spermatophores at the opening of the oviduct using a male-parallel mating posture, whereas smaller males attach spermatophores around the female buccal membrane using a male-upturned mating posture. If the route of egg transportation is taken into consideration, male-parallel mating would be expected to result in higher fertilization success than male-upturned mating. Although these male mating tactics are largely dependent on the body size of the male relative to that of the female, it is unclear how female choice affects the male's mating tactics and his mating success. Squids are highly visual animals, and they communicate through dynamic body patterning. In the present study, we observed that smaller male squids in captivity would attempt to mate with a larger female using the male-parallel tactic repeatedly, but they failed to be successful most of the time because of a rejection signal by the female. In contrast, when the males switched to the male-upturned tactic, the mating success rate was increased significantly, with much less female rejection signal. This finding suggests that female squids signal their mating receptivity visually and that male squids alter their mating tactics accordingly. This is the evidence to support the hypothesis that the switch in male mating tactics depends on female choice in oval squids and that this is transmitted via visual communication.

Dimorphic male squid show differential gonadal and ejaculate expenditure

Under intense sexual selection, males less successful in fighting and mate guarding often adopt alternative reproductive tactics. In many species, males employing alternative tactics show not only behavioral differences, but also divergences in morphology and physiology, a phenomenon called intrasexual male dimorphism. Herein, we investigated intrasexual male dimorphism in the loliginid squid Doryteuthis plei, associated with alternative mating tactics. We show that small males (sneakers) have spermatophores with discontinuously smaller sperm mass and longer spermatozoa than large males (consorts). Moreover, sneakers produce club-like spermatangia, whereas consorts produce hook-like spermatangia, each type of spermatangia associated with a different female storage site and adoption of a distinct mating position. We also show that dimorphic males have different gonadal investment, sneakers showing higher increment rates in testis mass and higher investment in spermatophoric complex than consorts. Under the complex squid mating system, with two distinct fertilization environments, we hypothesize that sneakers may maximize their reproductive success by both investing more in gonad growth and partitioning ejaculates into extra mating opportunities, whereas consorts may benefit from investment in somatic growth. Squids may be the first example of animals that, even with distinct sperm storage sites, fit the general predictions of sneaks and guards theoretical models.

Impact of cryptic female choice on insemination success: Larger sized and longer copulating male squid ejaculate more, but females influence insemination success by removing spermatangia.

In polyandrous mating systems, sperm competition and cryptic female choice (CFC) are well recognized as postcopulatory evolutionary forces. However, it remains challenging to separate CFC from sperm competition and to estimate how much CFC influences insemination success because those processes usually occur inside the female's body. The Japanese pygmy squid, Idiosepius paradoxus, is an ideal species in which to separate CFC from sperm competition because sperm transfer by the male and sperm displacement by the female can be observed directly at an external location on the female's body. Here, we counted the number of spermatangia transferred to, removed from, and remaining on the female body during single copulation episodes. We measured behavioral and morphological characteristics of the male, such as duration of copulation and body size. Although males with larger body size and longer copulation time were capable of transferring larger amounts of sperm, females preferentially eliminated sperm from males with larger body size and shorter copulation time by spermatangia removal; thus, CFC could attenuate sperm precedence by larger males, whereas it reinforces sperm precedence by males with longer copulation time. Genetic paternity analysis revealed that fertilisation success for each male was correlated with remaining sperm volume that is adjusted by females after copulation.

Sneaker Male Squid Produce Long-lived Spermatozoa by Modulating Their Energy Metabolism

Spermatozoa released by males should remain viable until fertilization. Hence, sperm longevity is governed by intrinsic and environmental factors in accordance with the male mating strategy. However, whether intraspecific variation of insemination modes can impact sperm longevity remains to be elucidated. In the squid Heterololigo bleekeri, male dimorphism (consort and sneaker) is linked to two discontinuous insemination modes that differ in place and time. Notably, only sneaker male spermatozoa inseminated long before egg spawning can be stored in the seminal receptacle. We found that sneaker spermatozoa exhibited greater persistence in fertilization competence and flagellar motility than consort ones because of a larger amount of flagellar glycogen. Sneaker spermatozoa also showed higher capacities in glucose uptake and lactate efflux. Lactic acidosis was considered to stabilize CO2-triggered self-clustering of sneaker spermatozoa, thus establishing hypoxia-induced metabolic changes and sperm survival. These results, together with comparative omics analyses, suggest that postcopulatory reproductive contexts define sperm longevity by modulating the inherent energy levels and metabolic pathways.

When should male squid prudently invest sperm?

Ejaculate production can be costly and males are expected to prudently allocate this potentially limiting resource to higher quality females. However, relatively little is known about facultative sperm allocation in response to the quality distribution of sequentially encountered females, despite this being a more realistic scenario for males in many species. Here, we examined patterns of male investment in a squid, Sepiadarium austrinum, when presented sequentially with small versus large females. Owing to a positive size – fecundity relationship in this species, large and small females are expected to differ in terms of their perceived quality to males as potential mating partners. Yet, despite large sperm investment and significant variation in female quality, sperm investment was determined only by mating order, with males consistently decreasing sperm investment in second matings. These results highlight that, when mates are encountered sequentially rather than simultaneously, prudent sperm allocation may not occur when it is otherwise predicted.

Male reproductive system and spermatophores production and storage in Histioteuthis bonnellii (Cephalopoda: Histioteuthidae): A look into deep-sea squids׳ reproductive strategy

Coleoid cephalopods go through a single breeding period in their life cycle, i.e., they are semelparous, although a great flexibility has been observed in their reproductive strategies, which range from simultaneous terminal spawning over a short period at the end of the animal׳s life to continuous spawning over a long period of the animal׳s life. So far, the information available on deep-sea species reproductive strategies is still poor and most of our knowledge about squid reproduction relates to females. In particular, not much is known on what strategy male squids have evolved to store sperm into spermatophores and adapt to semelparity. In this study an investigation of male reproductive strategy of the deep-sea umbrella squid Histioteuthis bonnellii (Férussac, 1835) is presented. The reproductive system was examined in 119 males caught in the Sardinian waters (Central Western Mediterranean) and is described for the first time. Results indicate that this species produces and stores spermatophores over a considerable period of time. The total number of spermatophores found in the reproductive system ranged between 12 and 3097 and the size of spermatophores stored by a single individual varied greatly, up to over 300%. Spermatophore length (SpL) gradually decreased towards the distal end of the reproductive system, so that spermatophores found in the proximal part of Needham׳s Sac were larger than those found in the terminal organ. Body size and SpL of spermatophores from the proximal part of Needham׳s Sac were positively correlated. Both indices of the sperm mass and of the ejaculatory apparatus decreased with the increase of SpL, while the cement body index increased, indicating that larger spermatophores contain less sperm and are equipped with larger cement bodies. Up to 64 spermatangia were found, exclusively in the terminal organ. The large size range of mature males (ML: 60.0–198.0mm; TW: 113.50–2409.00g) and the variation in spermatophore number and size indicate that in H. bonnellii males the allocation and storage of sperm start early in the individual life and extends in time, while animals continue to grow and produce spermatophores presumably more successful in attaching to female tissues. This pattern enlarges the time window available for reproduction and likely maximizes the percentage of mating success as the animals grow older and chances of mating events become comparatively lower, due to the basic low density of specimens in the deep-sea environment. Both aspects are potentially indicative of adaptation to the deep sea.

北太平洋柔鱼两个群体角质颚形态差异及生长特性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 北太平洋两个柔鱼群体角质颚形态及生长特征 DOI: 10.5846/stxb201301110083 作者: 作者单位: 上海海洋大学海洋科学学院;上海海洋大学海洋科学学院,上海海洋大学大洋渔业资源可持续开发省部共建教育部重点实验室;上海海洋大学大洋渔业资源可持续开发省部共建教育部重点实验室;上海海洋大学海洋科学学院;上海海洋大学海洋科学学院;上海海洋大学海洋科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（NSFC41276156）；国家863计划（2012AA092303）；上海市科技创新行动计划（12231203900） Morphology and growth of beaks in two cohorts for neon flying squid (Ommastrephes bartramii) in the North Pacific Ocean Author: Affiliation: College of Marine Sciences,Shanghai Ocean University;College of Marine Sciences,Shanghai Ocean University,The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources,Ministry of Education;College of Marine Sciences,Shanghai Ocean University;College of Marine Sciences,Shanghai Ocean University;College of Marine Sciences,Shanghai Ocean University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根据2011年5-11月我国鱿钓船在北太平洋海域（150°E-176°W）采集的渔获物样本，对柔鱼两个群体各项角质颚外部形态和生长进行分析。结果表明，角质颚参数值雌性均大于雄性，冬春生群体雌雄参数值间差异要大于秋生群体；角质颚各项参数值中，上头盖长（Upper Hood length， UHL）、上脊突长（Upper Crest length， UCL）、下脊突长（Lower crest length， LCL）、下翼长（Lower Wing length， LWL）与胴长、体重分别呈线性和指数关系（P < 0.01）。主成分分析认为，秋生群体雌、雄个体角质颚第一主成分因子均为UCL/ML，第二主成分因子均为UWL/ML，冬春生群体雌、雄个体角质颚第一主成分因子分别ULWL/ML和LLWL/ML，第二主成分分别与URW/ML和LRL/ML，这些这成分因子代表了角质颚水平和垂直方向上的生长特征。两个群体的雌性个体角质颚形态上存在显著差异，但雄性个体间差异不显著。方差分析（ANOVA）表明，2个群体不同胴长组间的角质颚形态均存在着显著差异（P < 0.01）；LSD法分析认为，除了秋生群体雌性个体上头盖长、上喙长、下头盖长、下喙宽在胴长组<250 mm和250-300 mm间不存在差异外，其他组之间均有着显著差异（P < 0.01）。同一群体不同性腺成熟度等级间的柔鱼角质颚形态存在显著差异（P < 0.01），但性成熟度为Ⅰ期和Ⅱ期时2个群体角质颚各项形态指标均存在显著差异（P < 0.01），而性成熟度Ⅲ期时则不存在差异（P > 0.05）。研究认为，不同群体的柔鱼角质颚形态及生长特征均存在着一定差异。 Abstract:Neon flying squid Ommastrephes bartramii an economically and ecologically important cephalopod, is one of main targeted species in the Chinese jigging squid fishery. In this paper, based on the samples collected by the Chinese squid jigging vessels during May to November in 2011 in the high seas of North Pacific Ocean (150°E-176°W), we compared differences in morphology and growth characteristics of beaks for two cohorts of O. bartramii. The results showed that females dominated in both the fall cohort and the winter-spring cohort. The morphological values in females' beak were larger than those of males, and the difference in these parameters between males and females in the winter-spring cohort was greater than that for the fall cohort. The upper hood length (UHL), upper crest length (UCL), lower crest length (LCL), lower wing length (LWL) had significant linear correlations with mantle length (ML) and significant exponential relationships with body weight (BW)(P < 0.01). The principal component analysis showed that the first principal component for the beak morphology of the fall cohort was related to UCL/ML of both males and females, and the second was UWL/ML. While for the winter-spring cohort, the first principal components of beak morphology were ULWL/ML and LLWL/ML, and the seconds were URW/ML and LRL/ML respectively, both represented the growth characteristics in horizontal and vertical directions. The morphology of beak for the two cohorts of female squid had significant differences, but no differences were found for male squid. The ANOVA indicated that the morphology of beak had significant differences among different ML groups(P < 0.01). However, the Least Significant Difference (LSD) analysis showed that the significant difference existed between the groups(P < 0.01)for all the morphological measurements except for UHL, URL, LHL and Lower Rostral width within the ranges of 250mm ML and 250-300mm ML for females of fall cohort. For the same corhot, the morphology of beak also had significant differences among different sex maturity stages(P < 0.01). The maturity stages I and II showed significant difference between the two cohorts, but no difference was found for stage III. In conclusion, the morphology and growth of beak for the two cohorts of O. bartramii differed with cohort, mantle length and sexual maturity. 参考文献 相似文献 引证文献

Sperm from Sneaker Male Squids Exhibit Chemotactic Swarming to CO2

Behavioral traits of sperm are adapted to the reproductive strategy that each species employs. In polyandrous species, spermatozoa often form motile clusters, which might be advantageous for competing with sperm from other males. Despite this presumed advantage for reproductive success, little is known about how sperm form such functional assemblies. Previously, we reported that males of the coastal squid Loligo bleekeri produce two morphologically different euspermatozoa that are linked to distinctly different mating behaviors. Consort and sneaker males use two distinct insemination sites, one inside and one outside the female's body, respectively. Here, we show that sperm release a self-attracting molecule that causes only sneaker sperm to swarm. We identified CO2 as the sperm chemoattractant and membrane-bound flagellar carbonic anhydrase as its sensor. Downstream signaling results from the generation of extracellular H(+), intracellular acidosis, and recovery from acidosis. These signaling events elicit Ca(2+)-dependent turning behavior, resulting in chemotactic swarming. These results illuminate the bifurcating evolution of sperm underlying the distinct fertilization strategies of this species.

Relationship between beak morphological variables and body size and mantle length of male and female Argentine shortfin squid (Illex argentinus)

Beak of cephalopod is an important hard tissue. Understanding the morphology of beak can yield critical information on the role of cephalopods in the ecosystem. The south patagonic stock of the Argentine shortfin squid, Illex argentinus, is not only one of the most important fishing targets, but also one of the most important species in the marine eco-system of the southwest Atlantic. A total of 430 samples of I. argentinus, including 229 females 103–346mm in mantle length (ML) and 201 males 140–298mm in ML, were collected from the area off the Exclusive Economic Zone of Argentinean waters by Chinese squid jigging vessels during February to May 2007. The morphology of their beaks was evaluated. The relationships between beak morphological variables and ML differed significantly among males and females. They could be best described by logarithmic functions for females and linear functions for males except for upper wing length (UWL) and lower rostrum length (LRL), which followed exponential functions in their relationships with ML. The results showed the sexual dimorphism in the relationship between ML and beak morphology for the south patagonic stock of I. argentinus. However, no significant difference was found between males and females in the relationships of beak morphological variables (except for UWL) versus body weight (BW), suggesting that the relationship between beak morphological variables and BW can be used for estimating the biomass consumed by their predators.

Revisiting a medical case of “stinging” in the human oral cavity caused by ingestion of raw squid (Cephalopoda: Teuthida): new data on the functioning of squid’s spermatophores

Male squid produce intricate spermatophores that, when transferred to the female, undergo the spermatophoric reaction, a complex process of evagination that leads to the attachment of the spermatangium, that is, the everted spermatophore containing the sperm mass. While this process is still not completely understood, the medical literature includes several reports of “oral stinging” (i.e., punctured wounds in the human oral cavity) following consumption of raw male squid, which contains undischarged spermatophores able to inflict such wounds. Here, we revisit a recent medical report of oral stinging by Shiraki et al. (Pathol Int 61:749–751, 2011), providing an in-depth reanalysis of their histological biopsies and revealing vital information on the functioning of squid spermatophores. The morphology of the spermatangia attached within the oral cavity is similar to the condition found in spermatangia naturally attached to female squids. The spermatangia were able to superficially puncture the superficial layers of the oral stratified squamous epithelium, and numerous, minute stellate particles from the squid spermatophore were found adhered to the oral epithelium. These findings corroborate previous hypotheses on the functioning of squid spermatophores, namely that spermatophore attachment generally involves tissue scarification, and that stellate particles play a vital role in the attachment process. Moreover, spermatophore attachment is confirmed to be autonomous (i.e., performed by the spermatophore itself) in another squid species (possibly a loliginid), and the results strongly indicate that the attachment mechanism is not dependent upon a specialized epithelium, nor a mate’s specific chemical stimulus. From the pathological point of view, the best prophylactic measure at present is the removal of the internal organs of the raw squid prior to its consumption.

Quantification of EPA and DHA in seafood of the south coast of Brazil

Purpose – The increase in seafood trade in recent years motivates more detailed studies of different species, as well as evaluation of the nutritional quality of their lipid content. Thus, the purpose of this paper is to evaluate the fatty acid composition, especially the concentrations and fractionation of omega‐3 essential fatty acid in classes of mussels (male and female), oysters, squid, and octopus captured on the south coast of Brazil.Design/methodology/approach – Fatty acid methyl esters were prepared by methylation of total lipids and were separated by gas chromatography. Quantification of LNA, AA, EPA, and DHA was done against tricosanoic acid methyl ester as an internal standard. Total lipids were fractionated into neutral lipids and polar lipids by classical column chromatography.Findings – The results of this study were as follows: the female mussel had the highest lipid content (3.52 per cent), followed by the male mussel (2.70 per cent), squid (1.05 per cent), octopus (0.79 per cent), and oy...

A shot in the dark: same-sex sexual behaviour in a deep-sea squid

Little is known about the reproductive habits of deep-living squids. Using remotely operated vehicles in the deep waters of the Monterey Submarine Canyon, we have found evidence of mating, i.e. implanted sperm packages, on similar body locations in males and females of the rarely seen mesopelagic squid Octopoteuthis deletron. Equivalent numbers of both sexes were found to have mated, indicating that male squid routinely and indiscriminately mate with both males and females. Most squid species are short-lived, semelparous (i.e. with a single, brief reproductive period) and promiscuous. In the deep, dark habitat where O. deletron lives, potential mates are few and far between. We suggest that same-sex mating behaviour by O. deletron is part of a reproductive strategy that maximizes success by inducing males to indiscriminately and swiftly inseminate every conspecific that they encounter.