Hanlon Roger T.

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Roger T.

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  • Article
    Squid have nociceptors that display widespread long-term sensitization and spontaneous activity after bodily injury
    (Society for Neuroscience, 2013-06-12) Crook, Robyn J. ; Hanlon, Roger T. ; Walters, Edgar T.
    Bodily injury in mammals often produces persistent pain that is driven at least in part by long-lasting sensitization and spontaneous activity (SA) in peripheral branches of primary nociceptors near sites of injury. While nociceptors have been described in lower vertebrates and invertebrates, outside of mammals there is limited evidence for peripheral sensitization of primary afferent neurons, and there are no reports of persistent SA being induced in primary afferents by noxious stimulation. Cephalopod molluscs are the most neurally and behaviorally complex invertebrates, with brains rivaling those of some vertebrates in size and complexity. This has fostered the opinion that cephalopods may experience pain, leading some governments to include cephalopods under animal welfare laws. It is not known, however, if cephalopods possess nociceptors, or whether their somatic sensory neurons exhibit nociceptive sensitization. We demonstrate that squid possess nociceptors that selectively encode noxious mechanical but not heat stimuli, and that show long-lasting peripheral sensitization to mechanical stimuli after minor injury to the body. As in mammals, injury in squid can cause persistent SA in peripheral afferents. Unlike mammals, the afferent sensitization and SA are almost as prominent on the contralateral side of the body as they are near an injury. Thus, while squid exhibit peripheral alterations in afferent neurons similar to those that drive persistent pain in mammals, robust changes far from sites of injury in squid suggest that persistently enhanced afferent activity provides much less information about the location of an injury in cephalopods than it does in mammals.
  • Article
    Defensive responses of cuttlefish to different teleost predators
    (Marine Biological Laboratory, 2013-12-01) Staudinger, Michelle D. ; Buresch, Kendra C. ; Mathger, Lydia M. ; Fry, Charlie ; McAnulty, Sarah ; Ulmer, Kimberly M. ; Hanlon, Roger T.
    We evaluated cuttlefish (Sepia officinalis) responses to three teleost predators: bluefish (Pomatomus saltatrix), summer flounder (Paralichthys dentatus), and black seabass (Centropristis striata). We hypothesized that the distinct body shapes, swimming behaviors, and predation tactics exhibited by the three fishes would elicit markedly different antipredator responses by cuttlefish. Over the course of 25 predator-prey behavioral trials, 3 primary and 15 secondary defense behaviors of cuttlefish were shown to predators. In contrast, secondary defenses were not shown during control trials in which predators were absent. With seabass—a benthic, sit-and-pursue predator—cuttlefish used flight and spent more time swimming in the water column than with other predators. With bluefish—an active, pelagic searching predator—cuttlefish remained closely associated with the substrate and relied more on cryptic behaviors. Startle (deimatic) displays were the most frequent secondary defense shown to seabass and bluefish, particularly the Dark eye ring and Deimatic spot displays. We were unable to evaluate secondary defenses by cuttlefish to flounder—a lie-and-wait predator—because flounder did not pursue cuttlefish or make attacks. Nonetheless, cuttlefish used primary defense during flounder trials, alternating between cryptic still and moving behaviors. Overall, our results suggest that cuttlefish may vary their behavior in the presence of different teleost predators: cryptic behaviors may be more important in the presence of active searching predators (e.g., bluefish), while conspicuous movements such as swimming in the water column and startle displays may be more prevalent with relatively sedentary, bottom-associated predators (e.g., seabass).
  • Article
    Cephalopod genomics : a plan of strategies and organization
    (Genomic Standards Consortium, 2012-09-26) Albertin, Caroline B. ; Bonnaud, Laure ; Brown, C. Titus ; Crookes-Goodson, Wendy J. ; da Fonseca, Rute R. ; Di Cristo, Carlo ; Dilkes, Brian P. ; Edsinger-Gonzales, Eric ; Freeman, Robert J. ; Hanlon, Roger T. ; Koenig, Kristen M. ; Lindgren, Annie R. ; Martindale, Mark Q. ; Minx, Patrick ; Moroz, Leonid L. ; Nodl, Marie-Therese ; Nyholm, Spencer V. ; Ogura, Atsushi ; Pungor, Judit R. ; Rosenthal, Joshua J. C. ; Schwarz, Erich M. ; Shigeno, Shuichi ; Strugnell, Jan M. ; Wollesen, Tim ; Zhang, Guojie ; Ragsdale, Clifton W.
    The Cephalopod Sequencing Consortium (CephSeq Consortium) was established at a NESCent Catalysis Group Meeting, “Paths to Cephalopod Genomics- Strategies, Choices, Organization,” held in Durham, North Carolina, USA on May 24-27, 2012. Twenty-eight participants representing nine countries (Austria, Australia, China, Denmark, France, Italy, Japan, Spain and the USA) met to address the pressing need for genome sequencing of cephalopod molluscs. This group, drawn from cephalopod biologists, neuroscientists, developmental and evolutionary biologists, materials scientists, bioinformaticians and researchers active in sequencing, assembling and annotating genomes, agreed on a set of cephalopod species of particular importance for initial sequencing and developed strategies and an organization (CephSeq Consortium) to promote this sequencing. The conclusions and recommendations of this meeting are described in this White Paper.
  • Article
    Acoustic detection and quantification of benthic egg beds of the squid Loligo opalescens in Monterey Bay, California
    (Acoustical Society of America, 2006-02) Foote, Kenneth G. ; Hanlon, Roger T. ; Iampietro, Pat J. ; Kvitek, Rikk G.
    The squid Loligo opalescens is a key species in the nearshore pelagic community of California, supporting the most valuable state marine fishery, yet the stock biomass is unknown. In southern Monterey Bay, extensive beds occur on a flat, sandy bottom, water depths 20–60 m, thus sidescan sonar is a prima-facie candidate for use in rapid, synoptic, and noninvasive surveying. The present study describes development of an acoustic method to detect, identify, and quantify squid egg beds by means of high-frequency sidescan-sonar imagery. Verification of the method has been undertaken with a video camera carried on a remotely operated vehicle. It has been established that sidescan sonar images can be used to predict the presence or absence of squid egg beds. The lower size limit of detectability of an isolated egg bed is about 0.5 m with a 400-kHz sidescan sonar used with a 50-m range when towed at 3 knots. It is possible to estimate the abundance of eggs in a region of interest by computing the cumulative area covered by the egg beds according to the sidescan sonar image. In a selected quadrat one arc second on each side, the estimated number of eggs was 36.5 million.
  • Article
    Vertical visual features have a strong influence on cuttlefish camouflage
    (Marine Biological Laboratory, 2013-04) Ulmer, Kevin M. ; Buresch, Kendra C. ; Kossodo, M. M. ; Mathger, Lydia M. ; Siemann, Liese A. ; Hanlon, Roger T.
    Cuttlefish and other cephalopods use visual cues from their surroundings to adaptively change their body pattern for camouflage. Numerous previous experiments have demonstrated the influence of two-dimensional (2D) substrates (e.g., sand and gravel habitats) on camouflage, yet many marine habitats have varied three-dimensional (3D) structures among which cuttlefish camouflage from predators, including benthic predators that view cuttlefish horizontally against such 3D backgrounds. We conducted laboratory experiments, using Sepia officinalis, to test the relative influence of horizontal versus vertical visual cues on cuttlefish camouflage: 2D patterns on benthic substrates were tested versus 2D wall patterns and 3D objects with patterns. Specifically, we investigated the influence of (i) quantity and (ii) placement of high-contrast elements on a 3D object or a 2D wall, as well as (iii) the diameter and (iv) number of 3D objects with high-contrast elements on cuttlefish body pattern expression. Additionally, we tested the influence of high-contrast visual stimuli covering the entire 2D benthic substrate versus the entire 2D wall. In all experiments, visual cues presented in the vertical plane evoked the strongest body pattern response in cuttlefish. These experiments support field observations that, in some marine habitats, cuttlefish will respond to vertically oriented background features even when the preponderance of visual information in their field of view seems to be from the 2D surrounding substrate. Such choices highlight the selective decision-making that occurs in cephalopods with their adaptive camouflage capability.
  • Article
    Lateralization of eye use in cuttlefish : opposite direction for anti-predatory and predatory behaviors
    (Frontiers Media, 2016-12-12) Schnell, Alexandra K. ; Hanlon, Roger T. ; Benkada, Aïcha ; jozet-alves, christelle
    Vertebrates with laterally placed eyes typically exhibit preferential eye use for ecological activities such as scanning for predators or prey. Processing visual information predominately through the left or right visual field has been associated with specialized function of the left and right brain. Lateralized vertebrates often share a general pattern of lateralized brain function at the population level, whereby the left hemisphere controls routine behaviors and the right hemisphere controls emergency responses. Recent studies have shown evidence of preferential eye use in some invertebrates, but whether the visual fields are predominately associated with specific ecological activities remains untested. We used the European common cuttlefish, Sepia officinalis, to investigate whether the visual field they use is the same, or different, during anti-predatory, and predatory behavior. To test for lateralization of anti-predatory behavior, individual cuttlefish were placed in a new environment with opaque walls, thereby obliging them to choose which eye to orient away from the opaque wall to scan for potential predators (i.e., vigilant scanning). To test for lateralization of predatory behavior, individual cuttlefish were placed in the apex of an isosceles triangular arena and presented with two shrimp in opposite vertexes, thus requiring the cuttlefish to choose between attacking a prey item to the left or to the right of them. Cuttlefish were significantly more likely to favor the left visual field to scan for potential predators and the right visual field for prey attack. Moreover, individual cuttlefish that were leftward directed for vigilant scanning were predominately rightward directed for prey attack. Lateralized individuals also showed faster decision-making when presented with prey simultaneously. Cuttlefish appear to have opposite directions of lateralization for anti-predatory and predatory behavior, suggesting that there is functional specialization of each optic lobe (i.e., brain structures implicated in visual processing). These results are discussed in relation to the role of lateralized brain function and the evolution of population level lateralization.
  • Article
    Clicking for calamari : toothed whales can echolocate squid Loligo pealeii
    (Inter-Research, 2007-11-27) Madsen, Peter T. ; Wilson, M. ; Johnson, Mark P. ; Hanlon, Roger T. ; Bocconcelli, Alessandro ; Aguilar De Soto, Natacha ; Tyack, Peter L.
    Squid play an important role in biomass turnover in marine ecosystems and constitute a food source for ~90% of all echolocating toothed whale species. Nonetheless, it has been hypothesized that the soft bodies of squid provide echoes too weak to be detected by toothed whale biosonars, and that only the few hard parts of the squid body may generate significant backscatter. We measured the acoustic backscatter from the common squid Loligo pealeii for signals similar to toothed whale echolocation clicks using an energy detector to mimic the mammalian auditory system. We show that the dorsal target strengths of L. pealeii with mantle lengths between 23 and 26 cm fall in the range from –38 to –44 dB, and that the pen, beak and lenses do not contribute significantly to the backscatter. Thus, the muscular mantle and fins of L. pealeii constitute a sufficient sonar target for individual biosonar detection by toothed whales at ranges between 25 and 325 m, depending on squid size, noise levels, click source levels, and orientation of the ensonified squid. While epipelagic squid must be fast and muscular to catch prey and avoid visual predators, it is hypothesized that some deep-water squid may have adopted passive acoustic crypsis, with a body of low muscle mass and low metabolism that will render them less conspicuous to echolocating predators.
  • Article
    Adaptable night camouflage by cuttlefish
    (University of Chicago Press, 2007-02-12) Hanlon, Roger T. ; Naud, Marie-Jose ; Forsythe, John W. ; Hall, Karina ; Watson, Anya C. ; McKechnie, Joy
    Cephalopods are well known for their diverse, quick‐changing camouflage in a wide range of shallow habitats worldwide. However, there is no documentation that cephalopods use their diverse camouflage repertoire at night. We used a remotely operated vehicle equipped with a video camera and a red light to conduct 16 transects on the communal spawning grounds of the giant Australian cuttlefish Sepia apama situated on a temperate rock reef in southern Australia. Cuttlefish ceased sexual signaling and reproductive behavior at dusk and then settled to the bottom and quickly adapted their body patterns to produce camouflage that was tailored to different backgrounds. During the day, only 3% of cuttlefish were camouflaged on the spawning ground, but at night 86% (71 of 83 cuttlefish) were camouflaged in variations of three body pattern types: uniform (n=5), mottled (n=33), or disruptive (n=34) coloration. The implication is that nocturnal visual predators provide the selective pressure for rapid, changeable camouflage patterning tuned to different visual backgrounds at night.
  • Preprint
    Hyperspectral imaging of cuttlefish camouflage indicates good color match in the eyes of fish predators
    ( 2011-03-31) Chiao, Chuan-Chin ; Wickiser, J. Kenneth ; Allen, Justine J. ; Genter, Brock ; Hanlon, Roger T.
    Camouflage is a widespread phenomenon throughout nature and an important anti-predator tactic in natural selection. Many visual predators have keen color perception, thus camouflage patterns should provide some degree of color matching in addition to other visual factors such as pattern, contrast, and texture. Quantifying camouflage effectiveness in the eyes of the predator is a challenge from the perspectives of both biology and optical imaging technology. Here we take advantage of Hyperspectral Imaging (HSI), which records full-spectrum light data, to simultaneously visualize color match and pattern match in the spectral and the spatial domains, respectively. Cuttlefish can dynamically camouflage themselves on any natural substrate and, despite their colorblindness, produce body patterns that appear to have high-fidelity color matches to the substrate when viewed directly by humans or with RGB images. Live camouflaged cuttlefish on natural backgrounds were imaged using HSI, and subsequent spectral analysis revealed that most reflectance spectra of individual cuttlefish and substrates were similar, rendering the color match possible. Modeling color vision of potential di- and tri-chromatic fish predators of cuttlefish corroborated the spectral match analysis and demonstrated that camouflaged cuttlefish show good color match as well as pattern match in the eyes of fish predators. These findings (i) indicate the strong potential of HSI technology to enhance studies 3 of biological coloration, and (ii) provide supporting evidence that cuttlefish can produce color-coordinated camouflage on natural substrates despite lacking color vision.
  • Article
    Multiple genetic stocks of longfin squid Loligo pealeii in the NW Atlantic : stocks segregate inshore in summer, but aggregate offshore in winter
    (Inter-Research, 2006-04-03) Buresch, Kendra C. ; Gerlach, Gabriele ; Hanlon, Roger T.
    The longfin squid Loligo pealeii is distributed widely in the NW Atlantic and is the target of a major fishery. A previous electrophoretic study of L. pealeii was unable to prove genetic differentiation, and the fishery has been managed as a single unit stock. We tested for population structure using 5 microsatellite loci. In early summer (June), when the squids had migrated inshore to spawn, we distinguished 4 genetically distinct stocks between Delaware and Cape Cod (ca. 490 km); a 5th genetic stock occurred in Nova Scotia and a 6th in the northern Gulf of Mexico. One of the summer inshore stocks did not show genetic differentiation from 2 of the winter offshore populations. We suggest that squids from summer locations overwinter in offshore canyons and that winter offshore fishing may affect multiple stocks of the inshore fishery. In spring, squids may segregate by genetic stock as they undertake their inshore migration, indicating an underlying mechanism of subpopulation recognition.
  • Article
    Octopus arms exhibit exceptional flexibility
    (Nature Research, 2020-11-30) Kennedy, E. B. Lane ; Buresch, Kendra C. ; Boinapally, Preethi ; Hanlon, Roger T.
    The octopus arm is often referred to as one of the most flexible limbs in nature, yet this assumption requires detailed inspection given that this has not been measured comprehensively for all portions of each arm. We investigated the diversity of arm deformations in Octopus bimaculoides with a frame-by-frame observational analysis of laboratory video footage in which animals were challenged with different tasks. Diverse movements in these hydrostatic arms are produced by some combination of four basic deformations: bending (orally, aborally; inward, outward), torsion (clockwise, counter-clockwise), elongation, and shortening. More than 16,500 arm deformations were observed in 120 min of video. Results showed that all eight arms were capable of all four types of deformation along their lengths and in all directions. Arms function primarily to bring the sucker-lined oral surface in contact with target surfaces. Bending was the most common deformation observed, although the proximal third of the arms performed relatively less bending and more shortening and elongation as compared with other arm regions. These findings demonstrate the exceptional flexibility of the octopus arm and provide a basis for investigating motor control of the entire arm, which may aid the future development of soft robotics.
  • Dataset
    An unexpected diversity of photoreceptor classes in the Longfin squid, Doryteuthis pealeii
    ( 2015-07-10) Kingston, Alexandra C. N. ; Wardill, Trevor J. ; Hanlon, Roger T. ; Cronin, Thomas W.
    Cephalopods are famous for their ability to change color and pattern rapidly for signaling and camouflage. They have keen eyes and remarkable vision, made possible by photoreceptors in their retinas. External to the eyes, photoreceptors also exist in parolfactory vesicles and some light organs, where they function using a rhodopsin protein that is identical to that expr essed in the retina. Furthermore, dermal chromatophore organs contain rhodopsin and other components of phototransduction (including retinochrome, a photoisomerase first found in the retina), suggesting that they are photoreceptive. In this study, we used a modified whole - mount immunohistochemical technique to explore rhodopsin and retinochrome expression in a number of tissues and organs in the longfin squid, Doryteuthis pealeii. We found that fin central muscles, hair cells (epithelial primary sensory neu rons), arm axial ganglia, and sucker peduncle nerves all express rhodopsin and retinochrome proteins. Our findings indicate that these animals possess an unexpected diversity of extraocular photoreceptors and suggest that extraocular photoreception using v isual opsins and visual phototransduction machinery is far more widespread throughout cephalopod tissues than previously recognized.
  • Preprint
    Biological versus electronic adaptive coloration : how can one inform the other?
    ( 2011-11) Kreit, Eric ; Mathger, Lydia M. ; Hanlon, Roger T. ; Dennis, Patrick B. ; Naik, Rajesh R. ; Forsythe, Eric ; Heikenfeld, Jason
    Adaptive reflective surfaces have been a challenge for both electronic paper (e-Paper) and biological organisms. Multiple colours, contrast, polarization, reflectance, diffusivity and texture must all be controlled simultaneously without optical losses in order to fully replicate the appearance of natural surfaces and vividly communicate information. This review merges the frontiers of knowledge for both biological adaptive coloration, with a focus on cephalopods, and synthetic reflective e-Paper within a consistent framework of scientific metrics. Currently, the highest performance approach for both nature and technology utilizes colourant transposition. Three outcomes are envisioned from this review: reflective display engineers may gain new insights from millions of years of natural selection and evolution; biologists will benefit from understanding the types of mechanisms, characterization, and metrics used in synthetic reflective e-Paper; all scientists will gain a clearer picture of the long-term prospects for capabilities such as adaptive concealment and signalling.
  • Preprint
    Potential for sound sensitivity in cephalopods
    ( 2010-07) Mooney, T. Aran ; Hanlon, Roger T. ; Madsen, Peter T. ; Christensen-Dalsgaard, Jakob ; Ketten, Darlene R. ; Nachtigall, Paul E.
    Hearing is a primary sense in many marine animals and we now have a reasonable understanding of what stimuli generate clear responses, the frequency range of sensitivity, expected threshold values and mecha-nisms of sound detection for several species of marine mammals and fishes (Fay 1988; Au et al. 2000). For marine invertebrates, our knowledge of hearing capabilities is relatively poor and a definition or even certainty of sound detection is not agreed upon (Webster et al. 1992) despite their magnitude of biomass and often central role in ocean ecosystems. Cephalopods (squid, cuttlefish, octopods and nautilus) are particularly interesting subjects for inver-tebrate sound detection investigations for several reasons. Ecologically, they occupy many of the same niches as sound-sensitive fish (Budelmann 1994) and may benefit from sound perception and use for the same reasons, such as to detect predators, navigate, or locate conspecifics. Squid, for example, are often the prey of loud, echolocating marine mammals (Clarke 1996), and may therefore be expected to have evolved hearing to avoid predators. Anatomically, squid have complex statocysts that are considered to serve primarily as vestibular and acceleration detectors (Nixon and Young 2003). However, statocysts may also be analogs for fish otolithic organs, detecting acoustic stimuli (Budelmann 1992). Previous studies have debated the subject of squid hearing and recently there has been a revival of research on the subject. Here, we briefly review what is known about squid sound detection, revisit hearing definitions, discuss potential squid susceptibility to anthropogenic noise and suggest potential future research direc-tions to examine squid acoustic sensitivity.
  • Preprint
    Expression of squid iridescence depends on environmental luminance and peripheral ganglion control
    ( 2013-10) Gonzalez-Bellido, Paloma T. ; Wardill, Trevor J. ; Buresch, Kendra C. ; Ulmer, Kevin M. ; Hanlon, Roger T.
    Squids display impressive changes in body coloration that are afforded by two types of dynamic skin elements: structural iridophores (which produce iridescence) and pigmented chromatophores. Both color elements are neurally controlled, but nothing is known about the iridescence circuit, or the environmental cues, that elicit iridescence expression. To tackle this knowledge gap, we performed denervation, electrical stimulation and behavioral experiments using the long-fin squid, Doryteuthis pealeii. We show that while the pigmentary and iridescence circuits originate in the brain, they are wired differently in the periphery: (i) the iridescence signals are routed through a peripheral center called the stellate ganglion and (ii) the iridescence motorneurons likely originate within this ganglion (as revealed by nerve fluorescence dye fills). Cutting the inputs to the stellate ganglion that descend from the brain shifts highly reflective iridophores into a transparent state. Taken together, these findings suggest that although brain commands are necessary for expression of iridescence, integration with peripheral information in the stellate ganglion could modulate the final output. We also demonstrate that squids change their iridescence brightness in response to environmental luminance; such changes are robust but slow (minutes to hours). The squid's ability to alter its iridescence levels may improve camouflage under different lighting intensities.
  • Article
    Dramatic fighting by male cuttlefish for a female mate
    (University of Chicago Press, 2017-05-02) Allen, Justine J. ; Akkaynak, Derya ; Schnell, Alexandra K. ; Hanlon, Roger T.
    Male cuttlefish compete for females with a repertoire of visually dramatic behaviors. Laboratory experiments have explored this system in Sepia officinalis, but corroborative field data have eluded collection attempts by many researchers. While scuba diving in Turkey, we fortuitously filmed an intense sequence of consort/intruder behaviors in which the consort lost and then regained his female mate from the intruder. These agonistic bouts escalated in stages, leading to fast dramatic expression of the elaborate intense zebra display and culminating in biting and inking as the intruder male attempted a forced copulation of the female. When analyzed in the context of game theory, the patterns of fighting behavior were more consistent with mutual assessment than self-assessment of fighting ability. Additional observations of these behaviors in nature are needed to conclusively determine which models best represent conflict resolution, but our field observations agree with laboratory findings and provide a valuable perspective.
  • Article
    Tactical decisions for changeable cuttlefish camouflage : visual cues for choosing masquerade are relevant from a greater distance than visual cues used for background matching
    (Marine Biological Laboratory, 2015-10-01) Buresch, Kendra C. ; Ulmer, Kimberly M. ; Cramer, Corinne ; McAnulty, Sarah ; Davison, William ; Mathger, Lydia M. ; Hanlon, Roger T.
    Cuttlefish use multiple camouflage tactics to evade their predators. Two common tactics are background matching (resembling the background to hinder detection) and masquerade (resembling an uninteresting or inanimate object to impede detection or recognition). We investigated how the distance and orientation of visual stimuli affected the choice of these two camouflage tactics. In the current experiments, cuttlefish were presented with three visual cues: 2D horizontal floor, 2D vertical wall, and 3D object. Each was placed at several distances: directly beneath (in a circle whose diameter was one body length (BL); at zero BL [(0BL); i.e., directly beside, but not beneath the cuttlefish]; at 1BL; and at 2BL. Cuttlefish continued to respond to 3D visual cues from a greater distance than to a horizontal or vertical stimulus. It appears that background matching is chosen when visual cues are relevant only in the immediate benthic surroundings. However, for masquerade, objects located multiple body lengths away remained relevant for choice of camouflage.
  • Article
    Evidence for biased use of sperm sources in wild female giant cuttlefish (Sepia apama)
    (Royal Society, 2005-05-22) Naud, Marie-Jose ; Shaw, Paul W. ; Hanlon, Roger T. ; Havenhand, Jon N.
    In species where females store sperm from their mates prior to fertilization, sperm competition is particularly probable. Female Sepia apama are polyandrous and have access to sperm from packages (spermatangia) deposited by males onto their buccal area during mating and to sperm stored in internal sperm-storage organs (receptacles) located below the beak. Here, we describe the structure of the sperm stores in the female's buccal area, use microsatellite DNA analyses to determine the genetic diversity of stored sperm and combine these data with offspring genotypes to determine the storage location of paternal sperm. The number of male genotypes represented in the sperm receptacles was significantly lower than that found among the spermatangia. Estimation of the volumes of sperm contained in the receptacles and the spermatangia were statistically comparable; however, paternal sperm were more likely to have come from spermatangia than from the sperm receptacles. These results confirm a genetic polyandrous mating system in this species and suggest that fertilization pattern with respect to the sperm stores used is not random.
  • Preprint
    Visual phototransduction components in cephalopod chromatophores suggest dermal photoreception
    ( 2015-04) Kingston, Alexandra C. N. ; Kuzirian, Alan M. ; Hanlon, Roger T. ; Cronin, Thomas W.
    Cephalopod molluscs are renowned for their colorful and dynamic body patterns, produced by an assemblage of skin components that interact with light. These may include iridophores, leucophores, chromatophores, and (in some species) photophores. Here, we present molecular evidence suggesting that cephalopod chromatophores, small dermal pigmentary organs that reflect various colors of light, are photosensitive. RT-PCR revealed the presence of transcripts encoding rhodopsin and retinochrome within the retinas and skin of the squid Doryteuthis pealeii, and the cuttlefish Sepia officinalis and Sepia latimanus. In D. pealeii, Gqα and squid TRP channel transcripts were present in the retina and in all dermal samples. Rhodopsin, retinochrome, and Gqα transcripts were also found in RNA extracts from dissociated chromatophores isolated from D. pealeii dermal tissues. In D. pealeii, immunohistochemical staining labeled rhodopsin, retinochrome, and Gqα proteins in several chromatophore components, including pigment cell membranes, radial muscle fibers, and sheath cells. This is the first evidence that cephalopod dermal tissues, and specifically chromatophores, may possess the requisite combination of molecules required to respond to light.
  • Preprint
    Microstructural and biochemical characterization of the nanoporous sucker rings from Dosidicus gigas
    ( 2008-11-24) Miserez, Ali ; Weaver, James C. ; Pedersen, Peter B. ; Schneeberk, Todd ; Hanlon, Roger T. ; Kisailus, David ; Birkedal, Henrik
    Recent interest in the development of environmentally benign routes to the synthesis of novel multifunctional materials has resulted in numerous investigations into structure-function relationships of a wide range of biological systems at the ultrastructural, micromechanical, and biochemical levels. While much of this research has concentrated on mineralized structures such as bone, mollusk shells sponge spicules and echinoderm ossicles, there is an equally broad range of animals whose skeletal structures are devoid of mineral components.One such group, the squids (Mollusca: Cephalopoda: Teuthoidea), are remarkable in several aspects. In addition to having an exceptionally well developed brain, sensory systems and skin (for adaptive coloration), these swift agile predators have eight flexible strong arms, two fast extensible tentacles, and strong malleable suckers, all of which are muscular hydrostats.