Recent papers

DWhatley

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tonmo

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Hey @gjbarord, note the cuttlebone paper above...

New paper:

Structure and mechanical properties of Octopus vulgaris suckers
Francesca Tramacere, Alexander Kovalev, Thomas Kleinteich, Stanislav N. Gorb, and Barbara Mazzolai

Abstract
In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers.

Keywords: octopus suckers, suction cup, elasticity modulus, viscoelasticity, bioinspiration
 

DWhatley

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Evolution of spermatophore transfer mechanisms in cephalopods
José Eduardo Amoroso Rodriguez Marian 2013 (subscription)

Abstract
Spermatophores from coleoid cephalopods are capable of functioning autonomously during mating, attaching themselves to the female body through the “spermatophoric reaction”. In decapodiforms this attachment involves some varying degree of implantation into female tissue, herein divided into shallow and deep implantation. This paper reviews the literature concerning the phenomenon of spermatophore implantation, and presents evidence corroborating a theoretical model ascribing the role of implantation to the ejaculatory apparatus, an invaginated tube found in the spermatophore oral region. In light of parsimonious character optimizations performed on published phylogenetic trees, two hypotheses for the evolution of spermatophore transfer mechanisms are tested. One hypothesis assumes that deep implantation arose first, shallow implantation evolving later associated with the emergence of specialized receptacles. The second hypothesis assumes that shallow implantation emerged first, deep implantation arising later, possibly associated with the adoption of deep-water lifestyles. Support for each hypothesis is dependent upon the phylogeny under consideration.
 

DWhatley

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Utilization of diets with different fish oil content in common octopus (Octopus vulgaris Cuvier, 1797) and resulting changes in its biochemical composition
Piedad S Morillo-Velarde, Jesús Cerezo Valverde, Benjamín García-García 2014 (subscription)

Abstract
The aim of the present work was to obtain the lipid utilization of Octopus vulgaris supplying formulated semi-moist diets with different contents in cod oil (reduced from water content): 0 g kg−1 (A0, 138 g kg−1 lipids DW; N = 4), 100 g kg−1 (A100, 286 g kg−1 lipids DW; N = 6) and 200 g kg−1 (A200, 388 g kg−1 lipids DW; N = 6). The rest of the ingredients were constant in the three diets: 200 g kg−1 gelatin, 100 g kg−1 egg yolk powder, 150 g kg−1 freeze-dried Todarodes sagittatus and 50 g kg−1 freeze-dried Sardinella aurita). Survival was 100% with the three diets. The highest absolute feeding (15.8 ± 1.2 g day−1), growth (9.6 ± 1.4 g day−1; 0.91% BW day−1) and feed efficiency rates (60.3%) were obtained with diet A0. This diet also showed greater retention of lipid and protein than A100 and A200. Protein digestibility was above 95% in all of the diets. Only diet A0 led to a high lipid digestibility coefficient (81.25%), which fell drastically to 12.3% in A200. It was notable the high polar lipid digestibility rates (83–89%) respect to neutral lipids (2–87%) in all diets. The best results were obtained with lipid feeding rates of around 1 g day−1 and a suitable lipid content on 130–140 g kg−1 DW in formulated diets for O. vulgaris.
 

DWhatley

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Close Genetic Relationships between Two American Octopuses: Octopus hubbsorum Berry, 1953, and Octopus mimus Gould, 1852
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Ricardo Pliego-Cárdenas ,Frederick G. Hochberg , Francisco Javier García De León, Irene De Los Angeles Barriga-Sosa

ABSTRACT

The octopuses Octopus hubbsorum and Octopus mimus are two species of octopuses that inhabit shallow waters of the eastern Pacific Ocean. The former species is found in the north, from the Gulf of California to Oaxaca, Mexico, whereas O. mimus lives in the south, from Peru to Chile. To infer the phylogenetic relationships between these species we used the mitochondrial genes cytochrome oxidase subunits I and III, and r16S with the aim of comparing their genetic distances with those of other Octopus sp. The genetic distance values between both species estimated per gene or concatenated were low (0%–1.6%) in comparison with other interspecific distances values (4.6%–18.4%). Application of 10× rule showed there is no overlap between intra- and interspecific octopus distances, whereas the application of the 4× rule confirmed that both octopuses belong to the same lineage. The resolved topologies with maximum parsimony and Bayesian approaches clustered the specimens of O. hubbsorum and O. mimus in a single clade with high bootstrap and posterior probability values (100 and 1.0, respectively). These results allow us to suggest that O. hubbsorum and O. mimus could represent the same species.
 

SepiaInc

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This is a really interesting recent release suggesting different hemocyte types:

Morphologic, cytometric and functional characterization of the common octopus (Octopus vulgaris) hemocytes
S. Castellanos-Martíneza, M. Prado-Alvarezb, A. Lobo-da-Cunhab, C. Azevedob, C. Gestala

http://www.sciencedirect.com/science/article/pii/S0145305X13003340

Abstract
The hemocytes of Octopus vulgaris were morphologically and functionally characterized. Light and electron microscopy (TEM and SEM), and flow cytometry analyses revealed the existence of two hemocyte populations. Large granulocytes showed U-shaped nucleus, a mean of 11.6 μm ± 1.2 in diameter with basophilic granules, polysaccharide and lysosomic deposits in the cytoplasm. Small granulocytes measured a mean of 8.1 μm ± 0.7 in diameter, and have a round nucleus occupying almost the entire cell and few or not granules in the cytoplasm. Flow cytometry analysis showed that large granulocytes are the principal cells that develop phagocytosis of latex beads (rising up to 56%) and ROS after zymosan stimulation. Zymosan induced the highest production of both ROS and NO. This study is the first tread towards understanding the O. vulgaris immune system by applying new tools to provide a most comprehensive morpho-functional study of their hemocytes.
 

SepiaInc

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Suggesting that variations in the immune system could be derived from adaptations to planktonic life? I suspect someone will be looking into similar relationships in the Euprymna symbiotic system since it's considered an immune model.
 

mucktopus

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I love this new paper. It's exactly the next step I would have taken with the A. aculeatus studies.

http://rd.springer.com/article/10.1007/s00227-014-2437-3

Aggressive male mating behavior depends on female maturity in Octopus bimaculoides
  • Sobhi Mohanty,
  • Alfredo F. Ojanguren,
  • Lee A. Fuiman
  • This laboratory study examined the combined effects of male and female behaviors on the outcome of mating encounters in Octopus bimaculoides. We found that male–male competition for mating opportunities depends on female maturity; the presence of immature females elicited significantly higher levels of aggression between competing males. We conclude that males are able to assess the reproductive status of females. The study also found that immature and mature females resisted male mating attempts to a similar extent but that males that showed more aggression toward male competitors were able to spend more time in contact with females. We suggest that the lack of prominent visual displays in these mating trials indicates the importance of chemical cues in Octopus mating systems, as has been demonstrated for other cephalopods. This study contributes to the growing research on cephalopod mating systems and in particular shows that Octopus mating dynamics may be more behaviorally complex than initially assumed.
 

DWhatley

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The study of deep-sea cephalopods
Hoving HJ, Perez JA, Bolstad KS, Braid HE, Evans AB3, Fuchs D, Judkins H, Kelly JT, Marian JE, Nakajima R, Piatkowski U, Reid A, Vecchione M, Xavier JC.

Abstract
"Deep-sea" cephalopods are here defined as cephalopods that spend a significant part of their life cycles outside the euphotic zone. In this chapter, the state of knowledge in several aspects of deep-sea cephalopod research are summarized, including information sources for these animals, diversity and general biogeography and life cycles, including reproduction. Recommendations are made for addressing some of the remaining knowledge deficiencies using a variety of traditional and more recently developed methods. The types of oceanic gear that are suitable for collecting cephalopod specimens and images are reviewed. Many groups of deep-sea cephalopods require taxonomic reviews, ideally based on both morphological and molecular characters. Museum collections play a vital role in these revisions, and novel (molecular) techniques may facilitate new use of old museum specimens. Fundamental life-cycle parameters remain unknown for many species; techniques developed for neritic species that could potentially be applied to deep-sea cephalopods are discussed. Reproductive tactics and strategies in deep-sea cephalopods are very diverse and call for comparative evolutionary and experimental studies, but even in the twenty-first century, mature individuals are still unknown for many species. New insights into diet and trophic position have begun to reveal a more diverse range of feeding strategies than the typically voracious predatory lifestyle known for many cephalopods. Regular standardized deep-sea cephalopod surveys are necessary to provide insight into temporal changes in oceanic cephalopod populations and to forecast, verify and monitor the impacts of global marine changes and human impacts on these populations.
 
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DWhatley

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Depth perception: cuttlefish (Sepia officinalis) respond to visual texture density gradients
Noam Josef, Ofri Mann, António V. Sykes, Graziano Fiorito, João Reis, Steven Maccusker, Nadav Shashar 2014 (subscription)

Abstract
Studies concerning the perceptual processes of animals are not only interesting, but are fundamental to the understanding of other developments in information processing among non-humans. Carefully used visual illusions have been proven to be an informative tool for understanding visual perception. In this behavioral study, we demonstrate that cuttlefish are responsive to visual cues involving texture gradients. Specifically, 12 out of 14 animals avoided swimming over a solid surface with a gradient picture that to humans resembles an illusionary crevasse, while only 5 out of 14 avoided a non-illusionary texture. Since texture gradients are well-known cues for depth perception in vertebrates, we suggest that these cephalopods were responding to the depth illusion created by the texture density gradient. Density gradients and relative densities are key features in distance perception in vertebrates. Our results suggest that they are fundamental features of vision in general, appearing also in cephalopods.
 

DWhatley

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The study of deep-sea cephalopods.
Hoving HJ, Perez JA, Bolstad KS, Braid HE, Evans AB, Fuchs D, Judkins H, Kelly JT, Marian JE, Nakajima R, Piatkowski U, Reid A, Vecchione M1, Xavier JC. 2014 (subscription)

Abstract
"Deep-sea" cephalopods are here defined as cephalopods that spend a significant part of their life cycles outside the euphotic zone. In this chapter, the state of knowledge in several aspects of deep-sea cephalopod research are summarized, including information sources for these animals, diversity and general biogeography and life cycles, including reproduction. Recommendations are made for addressing some of the remaining knowledge deficiencies using a variety of traditional and more recently developed methods. The types of oceanic gear that are suitable for collecting cephalopod specimens and images are reviewed. Many groups of deep-sea cephalopods require taxonomic reviews, ideally based on both morphological and molecular characters. Museum collections play a vital role in these revisions, and novel (molecular) techniques may facilitate new use of old museum specimens. Fundamental life-cycle parameters remain unknown for many species; techniques developed for neritic species that could potentially be applied to deep-sea cephalopods are discussed. Reproductive tactics and strategies in deep-sea cephalopods are very diverse and call for comparative evolutionary and experimental studies, but even in the twenty-first century, mature individuals are still unknown for many species. New insights into diet and trophic position have begun to reveal a more diverse range of feeding strategies than the typically voracious predatory lifestyle known for many cephalopods. Regular standardized deep-sea cephalopod surveys are necessary to provide insight into temporal changes in oceanic cephalopod populations and to forecast, verify and monitor the impacts of global marine changes and human impacts on these populations.
 

DWhatley

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The Taxonomy and Morphometry of Squids in the Family Loliginidae (Cephalopoda:Myopsida) from the Pacific Coast of Mexico Jasmin Granados-Amores, Francisco J. García-Rodríguez, F. G. Hochberg, César A. Salinas-Zavala 2014 (subscription)

Abstract:
The present research was a morphological and morphometric analysis of species from the family Loliginidae distributed in the Mexican Pacific and Gulf of California. These species are captured incidentally in shrimp fisheries and commercialized locally. Nevertheless, the number of species from the zone is uncertain, and there are numerous taxonomic problems in the group that limit the accurate identification of species and complicate the proper elaboration of the fisheries record. Morphological and morphometric analyses were performed using a canonical variable analysis (CVA) of 530 organisms. Six groups were separated a priori based on the shape of the funnel organ.
Based on the observed differences, four species were recognized: Lolliguncula (Lolliguncula) panamensis Berry, 1911, Lolliguncula (Lolliguncula) argus Brakoniecki and Roper, 1985, Lolliguncula (Loliolopsis) diomedeae (Hoyle, 1904), and Doryteuthis (Amerigo) opalescens (Berry, 1911). Two additional forms were recognized and named the following: Lolliguncula sp. 1, and Lolliguncula sp. 2. Three canonical variables (CV) explained 95.4% of variability among the groups in the analysis results. Variance percentages related to CV1, CV2, and CV3 were 61.9, 19.5, and 13.9%, respectively. A MANOVA analysis supported the statistically significant differences among the squid groups (Wilk's lambda = 0.023; F(752447) = 38.6; P < 0.0000). In accordance with the analyses developed in this research, it is evident that there are morphological and morphometric characteristics that indicate a greater diversity of taxa are present compared to the list of species previously reported off the Pacific coasts of Mexico.
 

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De Novo Transcriptome Sequencing of the Octopus vulgaris Hemocytes Using Illumina RNA-Seq Technology: Response to the Infection by the Gastrointestinal Parasite Aggregata octopiana
Sheila Castellanos-Martínez, David Arteta, Susana Catarino, Camino Gestal 2014 (full text)

Abstract
Background
Octopus vulgaris is a highly valuable species of great commercial interest and excellent candidate for aquaculture diversification; however, the octopus’ well-being is impaired by pathogens, of which the gastrointestinal coccidian parasite Aggregata octopiana is one of the most important. The knowledge of the molecular mechanisms of the immune response in cephalopods, especially in octopus is scarce. The transcriptome of the hemocytes of O. vulgaris was de novo sequenced using the high-throughput paired-end Illumina technology to identify genes involved in immune defense and to understand the molecular basis of octopus tolerance/resistance to coccidiosis.
Results
A bi-directional mRNA library was constructed from hemocytes of two groups of octopus according to the infection by A. octopiana, sick octopus, suffering coccidiosis, and healthy octopus, and reads were de novo assembled together. The differential expression of transcripts was analysed using the general assembly as a reference for mapping the reads from each condition. After sequencing, a total of 75,571,280 high quality reads were obtained from the sick octopus group and 74,731,646 from the healthy group. The general transcriptome of the O. vulgaris hemocytes was assembled in 254,506 contigs. A total of 48,225 contigs were successfully identified, and 538 transcripts exhibited differential expression between groups of infection. The general transcriptome revealed genes involved in pathways like NF-kB, TLR and Complement. Differential expression of TLR-2, PGRP, C1q and PRDX genes due to infection was validated using RT-qPCR. In sick octopuses, only TLR-2 was up-regulated in hemocytes, but all of them were up-regulated in caecum and gills.
Conclusion
The transcriptome reported here de novo establishes the first molecular clues to understand how the octopus immune system works and interacts with a highly pathogenic coccidian. The data provided here will contribute to identification of biomarkers for octopus resistance against pathogens, which could improve octopus farming in the near future.
 
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