Squid Sepioteuthis Lessoniana Research Articles

Squid adjust their body color according to substrate

Coleoid cephalopods camouflage on timescales of seconds to match their visual surroundings. To date, studies of cephalopod camouflage-to-substrate have been focused primarily on benthic cuttlefish and octopus, because they are readily found sitting on the substrate. In contrast to benthic cephalopods, oval squid (Sepioteuthis lessoniana species complex) are semi-pelagic animals that spend most of their time in the water column. In this study, we demonstrate that in captivity, S. lessoniana Sp.2 (Shiro-ika, white-squid) from the Okinawa archipelago, Japan, adapts the coloration of their skin using their chromatophores according to the background substrate. We show that if the animal moves between substrates of different reflectivity, the body patterning is changed to match. Chromatophore matching to substrate has not been reported in any loliginid cephalopod under laboratory conditions. Adaptation of the chromatophore system to the bottom substrate in the laboratory is a novel experimental finding that establishes oval squid as laboratory model animals for further research on camouflage.

Allometry for Eyes and Optic Lobes in Oval Squid (Sepioteuthis lessoniana) with Special Reference to Their Ontogenetic Asymmetry

Eyes develop in relation to body size and brain area for visual processing in some vertebrates. Meanwhile, it is well known that many animals exhibit left–right asymmetry in both morphology and behavior, namely, lateralization. However, it remains unclear whether the eyes and visual processing brain areas synchronously develop for their asymmetry. Oval squid (Sepioteuthis lessoniana) exhibits lateralization of optic lobe volume and left or right eye usage toward specific targets during their ontogeny. We address the question of how left–right asymmetry of the eyes and optic lobes exhibit an allometric pattern. To examine this question, we estimated the left and right volumes of eyes and optic lobes using microcomputed tomography. We found that, for the optic lobe volume, the right enlargement that appeared at ages 45 and 80 days then shifted to the left at age 120 days. In contrast, the volume of eyes did not show any left–right asymmetries from hatching to age 120 days. We also found that the volume of the eyes and optic lobes showed a slower increase than that of the whole-body size. Within these two visually related organs, the eyes grew faster than the optic lobes until age 120 days. These results are discussed in the context of the survival strategy of oval squid that form schools, two months post-hatching.

Location probing by males complicates sexual dynamics and successful mate‐guarding in squid groups

Reproductive fitness is defined by the successful passing of an individual's genes to the next generation. Cephalopods that mate in groups, in particular coastal squid and cuttlefish species, have evolved complex sexual tactics in order to maximize reproductive success (Morse and Huffard 2019). Through dynamic skin patterning accompanied by typical body postures, individuals send visual signals in the form of displays to potential mates and rival competitors, often engaging in escalating conflicts (Moynihan and Rodaniche 1982, Mather 2016).

Bacterial Dynamics in the Accessory Nidamental Gland of Sepioteuthis lessoniana throughout Maturation.

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.

Gross alpha and gross beta activities in selected marine species in Vietnam

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.

DINAMIKA POPULASI DAN LAJU EKSPLOITASI CUMI-CUMI (Sepioteuthis Lessoniana) DI KEPULAUAN SPERMONDE SULAWESI SELATAN

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.

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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.

Two distinct vitellogenin genes are similar in function and expression in the bigfin reef squid Sepioteuthis lessoniana.

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.

Spatiotemporal variations in life-history traits and statolith trace elements of Sepioteuthis lessoniana populations around northern Taiwan

The bigfin reef squid Sepioteuthis lessoniana is a neritic species widely distributed in coastal waters of the Indo-Pacific region and is of interest to fisheries for its high commercial value. Squid samples were collected from Keelung (KL) and Penghu (PH), around northern Taiwan from October 2012 to September 2013. A total of 949 squid were examined, and 620 squid were aged using statoliths. The age range of the squid in KL (55–183 days) was similar to that in PH (77–186 days). The squid hatched almost year-round, except in January and December in KL. Two seasonal cohorts were identified: a spring cohort (hatched in March to May) and an autumn cohort (July to October). Concentrations of nine trace elements in statoliths were analysed using solution-based inductively coupled plasma mass spectrometry (ICP-MS). Significant differences in Fe/Ca, Cu/Ca and Sr/Ca were found between the two locations, while significant differences in concentration ratios of Sr/Ca and Ba/Ca were noted between the two seasonal cohorts. Results of a principal component analysis and cluster analysis varied in life-history traits between the two geographic stocks and in elemental concentrations between the two seasonal cohorts. Squid in KL and PH might undertake different migration routes, while seasonal variability in oceanographic conditions was apparent in the two locations.

Morphological changes of the optic lobe from late embryonic to adult stages in oval squids Sepioteuthis lessoniana.

The optic lobe is the largest brain area within the central nervous system of cephalopods and it plays important roles in the processing of visual information, the regulation of body patterning, and locomotive behavior. The oval squid Sepioteuthis lessoniana has relatively large optic lobes that are responsible for visual communication via dynamic body patterning. It has been observed that the visual behaviors of oval squids change as the animals mature, yet little is known about how the structure of the optic lobes changes during development. The aim of the present study was to characterize the ontogenetic changes in neural organization of the optic lobes of S. lessoniana from late embryonic stage to adulthood. Magnetic resonance imaging and micro-CT scans were acquired to reconstruct the 3D-structure of the optic lobes and examine the external morphology at different developmental stages. In addition, optic lobe slices with nuclear staining were used to reveal changes in the internal morphology throughout development. As oval squids mature, the proportion of the brain making up the optic lobes increases continuously, and the optic lobes appear to have a prominent dent on the ventrolateral side. Inside the optic lobe, the cortex and the medulla expand steadily from the late embryonic stage to adulthood, but the cell islands in the tangential zone of the optic lobe decrease continuously in parallel. Interestingly, the size of the nuclei of cells within the medulla of the optic lobe increases throughout development. These findings suggest that the optic lobe undergoes continuous external morphological change and internal neural reorganization throughout the oval squid's development. These morphological changes in the optic lobe are likely to be responsible for changes in the visuomotor behavior of oval squids from hatching to adulthood.

Mismatch between the eye and the optic lobe in the giant squid.

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.

Quantitative Analysis of Dynamic Body Patterning Reveals the Grammar of Visual Signals during the Reproductive Behavior of the Oval Squid Sepioteuthis lessoniana

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.

Morphological characteristics of paralarvae of cephalopods found in Thai waters

Paralarvae of nine species of cephalopods, including the bobtail squid (Euprymna hyllebergi), sharp-tail pygmy squid (Idiosepius pygmaeus), bigfin reef squid (Sepioteuthis lessoniana), needle cuttlefish (Sepia aculeata), spineless cuttlefish (Sepiella inermis), Pharaoh cuttlefish (Sepia pharaonis), marble octopus (Amphioctopus aegina), lesser blue-ringed octopus (Hapalochaena maculosa), and muddy argonaut (Argonauta hians) were collected from broodstock that had been cultured in the laboratories of the Department of Marine Science, Faculty of Fisheries of Kasetsart University in Bangkok, Thailand. The external morphological characteristics of the paralarva of each species were observed and recorded, such as the number and pattern of chromatophores, weight, length, and length index of the mantle. The compiled information would be a useful reference for the identification of cephalopods, especially at species level.

Effect of Cadmium on the Embryonic Development and Hatching Rhythm of Big Fin Squid Sepioteuthis lessoniana, Lesson (1830) from Palk Strait, East Coast of India

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.

Collaborative adaptive management for bigfin squid applied to tourism-related activities in coastal waters of Northeast Taiwan

The bigfin squid Sepioteuthis lessoniana, a commercially important fishery resource and also an object of sightseeing for diving, are under risk situation arising from current management procedure in Taiwan. Significant decline in abundance of bigfin squid and destruction of suitable substrates for spawning of neritic squids in coastal waters of Northeast Taiwan has been noted by local fishermen in recent years. Local divers arbitrarily deployed bamboo clusters as a squid aggregation device, for mating and spawning, in order to restore the abundance of squid. The deployment of the devices was not approved by the government, in particular the fishery authorities. Following conflict and compromises, the bamboo clusters were placed in restricted regions with permission from the local government. However, the interim management measure faced a serious challenge. The fishing activity of fishermen and recreational anglers, who were not consulted for the interim measure, targeted the aggregated squids putting them at risk. To prevent hazards, a theoretical management model was proposed to involve and direct essential stakeholders in conservation and sustainable utilization of the resource. A fishbone diagram and spiral model was created to analyze and illustrate the potential problems. Collaborative management tools were applied to coordinate the participants' duties and responsibilities and build the interrelationships between them. Finally, a modified management model based on adaptive management strategies was developed to cope with the changing situations. This modified management model process might further serve as an example for conservation and management measures of other fisheries resources.

Microbial quality of frozen squid (Sepioteuthis lessoniana, Lesson 1830) treated with food grade commercial chemicals

Squids perish rapidly like other fishes and require some treatment to maintain the quality for export. The microbial quality of frozen squid (Sepioteuthis lessoniana, Lesson 1830) treated with the commercial food grade chemicals imported from Spain was therefore studied. Dressed squids were treated with the chemicals Hidratech_4A (0.4%) and Whitech_3 (0.25%) dissolved in chilled freshwater (STCF) and chilled saltwater (STCS). Chilled squids not treated served as control (SNTC). Squids were quick frozen at -40°C in contact plate freezer and stored at-20±1°C. Samples were tested raw, after pre-processing, treatments and freezing and during storage at monthly intervals for 7 months. The microbial quality evaluation included Total Plate Count (TPC), Escherichia coli, Staphylococcus aureus, Vibrio cholerae and Salmonella. Study revealed a better quality of treated samples than control. Microbiological quality of STCS was better than STCF and SNTC. E. coli counts decreased after treatment. Salmonella and V. cholerae were absent.

Variation in life-history traits for micro-cohorts of Sepioteuthis lessoniana in the waters off northern Taiwan

The bigfin reef squid Sepioteuthis lessoniana is a neritic squid widely distributed in the Indo-Pacific region and of interest to fisheries for its high commercial value. The age and growth of this squid has been studied along its distribution range, from Japan to Australia; however, the life-history parameters of this squid around Taiwan are unclear. In this study, growth and maturation of S. lessoniana in the waters off northern Taiwan between April 2009 and March 2010 was studied using statolith microstructure analysis. Statoliths of 142 females (88–355 mm mantle length, ML) and 129 males (85–401 mm ML) were read. The oldest female was mature at 216 days (355 mm ML), whereas the oldest male was mature at 209 days (345 mm ML). The squids hatch almost year-round, except in January and February, peaking in May and August–September. The ML-at-age data were best described by Schnute and linear functions for the females and males, respectively. The males attained a higher size-at-age than the females. Maturity ogives by age and ML class indicated that females mature later and at a larger size than males. Growth and maturation parameters of seasonal cohorts showed little difference, although squids hatching in warmer seasons tend to have a faster growth rate and higher size-at-age than those hatching in colder seasons for both sexes. The differences of life-history traits between seasonal cohorts could be inferred by progressive changes in the life-history traits of the squids hatching during transitional months, i.e. months between two peak seasons. These results provide essential life-history traits and improve our understanding of S. lessoniana populations in the waters off northern Taiwan.

Branchial NH4+-dependent acid–base transport mechanisms and energy metabolism of squid (Sepioteuthis lessoniana) affected by seawater acidification

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. 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. 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.

Isolation and structural characterisation of acid- and pepsin-soluble collagen from the skin of squid Sepioteuthis lessoniana (Lesson, 1830)

Acid-solubilised collagen (ASC) and pepsin-solubilised collagen (PSC) were effectively isolated from squid skin with good yield and total protein content. ASC and PSC consist of two α-chains with an imino acid content of 182.6 and 184 imino acid residues/1000 residues. The molecular weight was determined to be between 73 and 107 kDa by using SDS-PAGE. For peptide mapping, collagens were digested with achromo endopeptidase, and all components, including α, β-chains, were markedly hydrolysed. Degradation peptides with molecular weights between 106.9 and 15.47 kDa were obtained. UV–vis absorption spectrum revealed distinct absorption at 220–240 nm. FT-IR spectra of collagens were almost similar when compared with standard. In differential scanning calorimetry profile, ASC and PSC exhibited a To of 59.10, 62.18°C and TP of 104.91, 98.10 °C, respectively. This investigation indicates that the collagen isolated from the squid skin, which is thrown as waste in the seafood-processing plant, might supplement the vertebrate collagen in industrial applications.