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Hillel J Chiel - One of the best experts on this subject based on the ideXlab platform.

  • soft surface grasping Radular opening in aplysia californica
    The Journal of Experimental Biology, 2019
    Co-Authors: Catherine Kehl, David M Neustadter, Richard F Drushel, Rebekah K Smoldt, Hillel J Chiel
    Abstract:

    Grasping soft, irregular material is challenging both for animals and robots. The feeding systems of many animals have adapted to this challenge. In particular, the feeding system of the marine mollusk Aplysia californica, a generalist herbivore, allows it to grasp and ingest seaweeds of varying shape, texture and toughness. On the surface of the grasper of A. californica is a structure known as the Radula, a thin flexible cartilaginous sheet with fine teeth. Previous in vitro studies suggested that intrinsic muscles, I7, are responsible for opening the Radula. Lesioning I7 in vivo does not prevent animals from grasping and ingesting food. New in vitro studies demonstrate that a set of fine muscle fibers on the ventral surface of the Radula - the sub-Radular fibers (SRFs) - mediate opening movements even if the I7 muscles are absent. Both in vitro and in vivo lesions demonstrate that removing the SRFs leads to profound deficits in Radular opening, and significantly reduces feeding efficiency. A theoretical biomechanical analysis of the actions of the SRFs suggests that they induce the Radular surface to open around a central crease in the Radular surface and to arch the Radular surface, allowing it to softly conform to irregular material. A three-dimensional model of the Radular surface, based on in vivo observations and magnetic resonance imaging of intact animals, provides support for the biomechanical analysis. These results suggest how a soft grasper can work during feeding, and suggest novel designs for artificial soft graspers.

  • mechanical reconfiguration mediates swallowing and rejection in aplysia californica
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2006
    Co-Authors: David M Neustadter, Gregory P. Sutton, Randall D. Beer, Valerie A Novakovic, Hillel J Chiel
    Abstract:

    Muscular hydrostats, such as tongues, trunks or tentacles, have fewer constraints on their degrees of freedom than musculoskeletal systems, so changes in a structure’s shape may alter the positions and lengths of other components (i.e., induce mechanical reconfiguration). We studied mechanical reconfiguration during rejection and swallowing in the marine mollusk Aplysia californica. During rejection, inedible material is pushed out of an animal’s buccal cavity. The grasper (Radula/odontophore) closes on inedible material, and then a posterior muscle, I2, pushes the grasper toward the jaws (protracts it). After the material is released, an anterior muscle complex (the I1/I3/jaw complex) pushes the grasper toward the esophagus (retracts it). During swallowing, the grasper is protracted open, and then retracts closed, pulling in food. Grasper closure changes its shape. Magnetic resonance images show that grasper closure lengthens I2. A kinetic model quantified the changes in the ability of I2 and I1/I3 to exert force as grasper shape changed. Grasper closure increases I2’s ability to protract during rejection, and increases I1/I3’s ability to retract during swallowing. Motor neurons controlling Radular closure may therefore affect the behavioral outputs of I2’s and I1/I3’s motor neurons. Thus, motor neurons may modulate the outputs of other motor neurons through mechanical reconfiguration.

  • Neural control exploits changing mechanical advantage and context dependence to generate different feeding responses in Aplysia
    Biological Cybernetics, 2004
    Co-Authors: Gregory P. Sutton, David M Neustadter, Patrick E Crago, Elizabeth V Mangan, Randall D. Beer, Hillel J Chiel
    Abstract:

    How does neural control reflect changes in mechanical advantage and muscle function? In the Aplysia feeding system a protractor muscle’s mechanical advantage decreases as it moves the structure that grasps food (the Radula/odontophore) in an anterior direction. In contrast, as the Radula/odontophore is moved forward, the jaw musculature’s mechanical advantage shifts so that it may act to assist forward movement of the Radula/odontophore instead of pushing it posteriorly. To test whether the jaw musculature’s context-dependent function can compensate for the falling mechanical advantage of the protractor muscle, we created a kinetic model of Aplysia ’s feeding apparatus. During biting, the model predicts that the reduction of the force in the protractor muscle I2 will prevent it from overcoming passive forces that resist the large anterior Radula/odontophore displacements observed during biting. To produce protractions of the magnitude observed during biting behaviors, the nervous system could increase I2’s contractile strength by neuromodulating I2, or it could recruit the I1/I3 jaw muscle complex. Driving the kinetic model with in vivo EMG and ENG predicts that, during biting, early activation of the context-dependent jaw muscle I1/I3 may assist in moving the Radula/odontophore anteriorly during the final phase of protraction. In contrast, during swallowing, later activation of I1/I3 causes it to act purely as a retractor. Shifting the timing of onset of I1/I3 activation allows the nervous system to use a mechanical equilibrium point that allows I1/I3 to act as a protractor rather than an equilibrium point that allows I1/I3 to act as a retractor. This use of equilibrium points may be similar to that proposed for vertebrate control of movement.

  • a kinematic model of swallowing in aplysia californica based on Radula odontophore kinematics and in vivo magnetic resonance images
    The Journal of Experimental Biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J Chiel
    Abstract:

    A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the odontophore, the muscular structure that underlies the pincer-like grasping structure, the Radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the Radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of Radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the Radular stalk and the I5 (ARC) muscle during Radular opening and closing.

  • Kinematics of the buccal mass during swallowing based on magnetic resonance imaging in intact, behaving Aplysia californica.
    The Journal of experimental biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Hillel J Chiel
    Abstract:

    A novel magnetic resonance imaging interface has been developed that makes it possible to image movements in intact, freely moving subjects. We have used this interface to image the internal structures of the feeding apparatus (i.e. the buccal mass) of the marine mollusc Aplysia californica. The temporal and spatial resolution of the resulting images is sufficient to describe the kinematics of specific muscles of the buccal mass and the internal movements of the main structures responsible for grasping food, the Radula and the odontophore. These observations suggest that a previously undescribed feature on the anterior margin of the odontophore, a fluid-filled structure that we term the prow, may aid in opening the jaw lumen early in protraction. Radular closing during swallowing occurs near the peak of protraction as the Radular stalk is pushed rapidly out of the odontophore. Retraction of the odontophore is enhanced by the closure of the lumen of the jaws on the elongated odontophore, causing the odontophore to rotate rapidly towards the esophagus. Radular opening occurs after the peak of retraction and without the active contraction of the protractor muscle 12 and is due, in part, to the movement of the Radular stalk into the odontophore. The large variability between responses also suggests that the great flexibility of swallowing responses may be due to variability in neural control and in the biomechanics of the ingested food and to the inherent flexibility of the buccal mass.

David M Neustadter - One of the best experts on this subject based on the ideXlab platform.

  • soft surface grasping Radular opening in aplysia californica
    The Journal of Experimental Biology, 2019
    Co-Authors: Catherine Kehl, David M Neustadter, Richard F Drushel, Rebekah K Smoldt, Hillel J Chiel
    Abstract:

    Grasping soft, irregular material is challenging both for animals and robots. The feeding systems of many animals have adapted to this challenge. In particular, the feeding system of the marine mollusk Aplysia californica, a generalist herbivore, allows it to grasp and ingest seaweeds of varying shape, texture and toughness. On the surface of the grasper of A. californica is a structure known as the Radula, a thin flexible cartilaginous sheet with fine teeth. Previous in vitro studies suggested that intrinsic muscles, I7, are responsible for opening the Radula. Lesioning I7 in vivo does not prevent animals from grasping and ingesting food. New in vitro studies demonstrate that a set of fine muscle fibers on the ventral surface of the Radula - the sub-Radular fibers (SRFs) - mediate opening movements even if the I7 muscles are absent. Both in vitro and in vivo lesions demonstrate that removing the SRFs leads to profound deficits in Radular opening, and significantly reduces feeding efficiency. A theoretical biomechanical analysis of the actions of the SRFs suggests that they induce the Radular surface to open around a central crease in the Radular surface and to arch the Radular surface, allowing it to softly conform to irregular material. A three-dimensional model of the Radular surface, based on in vivo observations and magnetic resonance imaging of intact animals, provides support for the biomechanical analysis. These results suggest how a soft grasper can work during feeding, and suggest novel designs for artificial soft graspers.

  • mechanical reconfiguration mediates swallowing and rejection in aplysia californica
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2006
    Co-Authors: David M Neustadter, Gregory P. Sutton, Randall D. Beer, Valerie A Novakovic, Hillel J Chiel
    Abstract:

    Muscular hydrostats, such as tongues, trunks or tentacles, have fewer constraints on their degrees of freedom than musculoskeletal systems, so changes in a structure’s shape may alter the positions and lengths of other components (i.e., induce mechanical reconfiguration). We studied mechanical reconfiguration during rejection and swallowing in the marine mollusk Aplysia californica. During rejection, inedible material is pushed out of an animal’s buccal cavity. The grasper (Radula/odontophore) closes on inedible material, and then a posterior muscle, I2, pushes the grasper toward the jaws (protracts it). After the material is released, an anterior muscle complex (the I1/I3/jaw complex) pushes the grasper toward the esophagus (retracts it). During swallowing, the grasper is protracted open, and then retracts closed, pulling in food. Grasper closure changes its shape. Magnetic resonance images show that grasper closure lengthens I2. A kinetic model quantified the changes in the ability of I2 and I1/I3 to exert force as grasper shape changed. Grasper closure increases I2’s ability to protract during rejection, and increases I1/I3’s ability to retract during swallowing. Motor neurons controlling Radular closure may therefore affect the behavioral outputs of I2’s and I1/I3’s motor neurons. Thus, motor neurons may modulate the outputs of other motor neurons through mechanical reconfiguration.

  • Neural control exploits changing mechanical advantage and context dependence to generate different feeding responses in Aplysia
    Biological Cybernetics, 2004
    Co-Authors: Gregory P. Sutton, David M Neustadter, Patrick E Crago, Elizabeth V Mangan, Randall D. Beer, Hillel J Chiel
    Abstract:

    How does neural control reflect changes in mechanical advantage and muscle function? In the Aplysia feeding system a protractor muscle’s mechanical advantage decreases as it moves the structure that grasps food (the Radula/odontophore) in an anterior direction. In contrast, as the Radula/odontophore is moved forward, the jaw musculature’s mechanical advantage shifts so that it may act to assist forward movement of the Radula/odontophore instead of pushing it posteriorly. To test whether the jaw musculature’s context-dependent function can compensate for the falling mechanical advantage of the protractor muscle, we created a kinetic model of Aplysia ’s feeding apparatus. During biting, the model predicts that the reduction of the force in the protractor muscle I2 will prevent it from overcoming passive forces that resist the large anterior Radula/odontophore displacements observed during biting. To produce protractions of the magnitude observed during biting behaviors, the nervous system could increase I2’s contractile strength by neuromodulating I2, or it could recruit the I1/I3 jaw muscle complex. Driving the kinetic model with in vivo EMG and ENG predicts that, during biting, early activation of the context-dependent jaw muscle I1/I3 may assist in moving the Radula/odontophore anteriorly during the final phase of protraction. In contrast, during swallowing, later activation of I1/I3 causes it to act purely as a retractor. Shifting the timing of onset of I1/I3 activation allows the nervous system to use a mechanical equilibrium point that allows I1/I3 to act as a protractor rather than an equilibrium point that allows I1/I3 to act as a retractor. This use of equilibrium points may be similar to that proposed for vertebrate control of movement.

  • a kinematic model of swallowing in aplysia californica based on Radula odontophore kinematics and in vivo magnetic resonance images
    The Journal of Experimental Biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J Chiel
    Abstract:

    A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the odontophore, the muscular structure that underlies the pincer-like grasping structure, the Radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the Radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of Radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the Radular stalk and the I5 (ARC) muscle during Radular opening and closing.

  • Kinematics of the buccal mass during swallowing based on magnetic resonance imaging in intact, behaving Aplysia californica.
    The Journal of experimental biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Hillel J Chiel
    Abstract:

    A novel magnetic resonance imaging interface has been developed that makes it possible to image movements in intact, freely moving subjects. We have used this interface to image the internal structures of the feeding apparatus (i.e. the buccal mass) of the marine mollusc Aplysia californica. The temporal and spatial resolution of the resulting images is sufficient to describe the kinematics of specific muscles of the buccal mass and the internal movements of the main structures responsible for grasping food, the Radula and the odontophore. These observations suggest that a previously undescribed feature on the anterior margin of the odontophore, a fluid-filled structure that we term the prow, may aid in opening the jaw lumen early in protraction. Radular closing during swallowing occurs near the peak of protraction as the Radular stalk is pushed rapidly out of the odontophore. Retraction of the odontophore is enhanced by the closure of the lumen of the jaws on the elongated odontophore, causing the odontophore to rotate rapidly towards the esophagus. Radular opening occurs after the peak of retraction and without the active contraction of the protractor muscle 12 and is due, in part, to the movement of the Radular stalk into the odontophore. The large variability between responses also suggests that the great flexibility of swallowing responses may be due to variability in neural control and in the biomechanics of the ingested food and to the inherent flexibility of the buccal mass.

Sirenko Boris - One of the best experts on this subject based on the ideXlab platform.

Richard F Drushel - One of the best experts on this subject based on the ideXlab platform.

  • soft surface grasping Radular opening in aplysia californica
    The Journal of Experimental Biology, 2019
    Co-Authors: Catherine Kehl, David M Neustadter, Richard F Drushel, Rebekah K Smoldt, Hillel J Chiel
    Abstract:

    Grasping soft, irregular material is challenging both for animals and robots. The feeding systems of many animals have adapted to this challenge. In particular, the feeding system of the marine mollusk Aplysia californica, a generalist herbivore, allows it to grasp and ingest seaweeds of varying shape, texture and toughness. On the surface of the grasper of A. californica is a structure known as the Radula, a thin flexible cartilaginous sheet with fine teeth. Previous in vitro studies suggested that intrinsic muscles, I7, are responsible for opening the Radula. Lesioning I7 in vivo does not prevent animals from grasping and ingesting food. New in vitro studies demonstrate that a set of fine muscle fibers on the ventral surface of the Radula - the sub-Radular fibers (SRFs) - mediate opening movements even if the I7 muscles are absent. Both in vitro and in vivo lesions demonstrate that removing the SRFs leads to profound deficits in Radular opening, and significantly reduces feeding efficiency. A theoretical biomechanical analysis of the actions of the SRFs suggests that they induce the Radular surface to open around a central crease in the Radular surface and to arch the Radular surface, allowing it to softly conform to irregular material. A three-dimensional model of the Radular surface, based on in vivo observations and magnetic resonance imaging of intact animals, provides support for the biomechanical analysis. These results suggest how a soft grasper can work during feeding, and suggest novel designs for artificial soft graspers.

  • a kinematic model of swallowing in aplysia californica based on Radula odontophore kinematics and in vivo magnetic resonance images
    The Journal of Experimental Biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J Chiel
    Abstract:

    A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the odontophore, the muscular structure that underlies the pincer-like grasping structure, the Radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the Radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of Radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the Radular stalk and the I5 (ARC) muscle during Radular opening and closing.

  • Kinematics of the buccal mass during swallowing based on magnetic resonance imaging in intact, behaving Aplysia californica.
    The Journal of experimental biology, 2002
    Co-Authors: David M Neustadter, Richard F Drushel, Hillel J Chiel
    Abstract:

    A novel magnetic resonance imaging interface has been developed that makes it possible to image movements in intact, freely moving subjects. We have used this interface to image the internal structures of the feeding apparatus (i.e. the buccal mass) of the marine mollusc Aplysia californica. The temporal and spatial resolution of the resulting images is sufficient to describe the kinematics of specific muscles of the buccal mass and the internal movements of the main structures responsible for grasping food, the Radula and the odontophore. These observations suggest that a previously undescribed feature on the anterior margin of the odontophore, a fluid-filled structure that we term the prow, may aid in opening the jaw lumen early in protraction. Radular closing during swallowing occurs near the peak of protraction as the Radular stalk is pushed rapidly out of the odontophore. Retraction of the odontophore is enhanced by the closure of the lumen of the jaws on the elongated odontophore, causing the odontophore to rotate rapidly towards the esophagus. Radular opening occurs after the peak of retraction and without the active contraction of the protractor muscle 12 and is due, in part, to the movement of the Radular stalk into the odontophore. The large variability between responses also suggests that the great flexibility of swallowing responses may be due to variability in neural control and in the biomechanics of the ingested food and to the inherent flexibility of the buccal mass.

Sanamyan Karen - One of the best experts on this subject based on the ideXlab platform.

  • FIGURE 11 in Description of the first cryptobranch onchidoridid Onchimira cavifera gen. et sp. nov., and of three new species of the genera Adalaria Bergh, 1879 and Onchidoris Blainville, 1816 (Nudibranchia: Onchidorididae) from Kamchatka waters
    2018
    Co-Authors: Martynov Alexander, Korshunova Tatiana, Sanamyan Nadezhda, Sanamyan Karen
    Abstract:

    FIGURE 11. Radulae of species of the genus Adalaria, scanning electron micrographs. A – C, Adalaria slavi sp. nov., paratype ZMMU Lc- 37457, living specimen, 18 mm length; A. Middle part of the Radula; B. Several middle rows showing outer laterals; C. Enlarged first laterals showing cusp denticle pattern; D. Adalaria slavi sp. nov., paratype ZMMU Lc- 37460, juvenile, 7 mm, middle part of the Radula; E – F, Adalaria olgae sp. nov., paratype ZMMU Lc- 37454, living specimen, 9 mm length; E. Middle part of the Radula; F. Few enlarged middle rows showing cusp denticles pattern of the first laterals and outer lateral teeth; G. Adalaria proxima (Alder & Hancock, 1854), ZMMU, not registered, Barents Sea, Dalne-Zelenetskaya Bay, living non-mature specimen with poorly differentiated reproductive system and smooth first lateral teeth, 15 mm length, intertidal, middle part of the Radula; H. Adalaria olgae sp. nov., paratype, ZMMU Lc- 37455, living specimen, 10 mm length, middle part of the Radula; I. Adalaria tschuktschica Krause, 1885, ZMMU, not registered, preserved specimen, 8 mm length, Chukchi Sea, Vrangel. Id., from 7 m depth, close up of the first laterals from the middle part of the Radula showing pattern of cusp denticles; J – K, Adalaria jannae Millen 1987, ZMMU, not registered, living specimen, 8 mm length, Starichkov Island; J. Middle part of the Radula, showing outer lateral teeth; K. Close up of the first laterals showing pattern of cusp denticles; L. Adalaria proxima (Alder et Hancock, 1854), ZMMU, not registered, juvenile specimen, 5 mm length, White Sea; M. Adalaria tschuktschica, middle part of the Radula. Scale bars: A ― 50 μm, B ― 50 μm, C ― 20 μm, D ― 20 μm, E ― 50 μm, F ― 20 μm, G ― 30 μm, H ― 50 μm, I ― 20 μm, J ― 20 μm, K ― 20 μm, L ― 30 μm, M ― 50 μm. Photos: Alexander Martynov

  • FIGURE 14 in Description of the first cryptobranch onchidoridid Onchimira cavifera gen. et sp. nov., and of three new species of the genera Adalaria Bergh, 1879 and Onchidoris Blainville, 1816 (Nudibranchia: Onchidorididae) from Kamchatka waters
    2018
    Co-Authors: Martynov Alexander, Korshunova Tatiana, Sanamyan Nadezhda, Sanamyan Karen
    Abstract:

    FIGURE 14. Radulae of species of the genus Onchidoris, scanning electron micrographs. A – C Onchidoris macropompa sp. nov., paratype ZMMU Lc- 37465, living specimen, 15 mm length, NW Pacific, Kamchatka peninsula, Starichkov Island; A. Part of the Radula; B. Middle rows enlarged, showing straight smooth first lateral teeth; C. Anterior rows enlarged, showing straight smooth first lateral teeth; D. Onchidoris macropompa sp. nov., paratype ZMMU Lc- 37467, preserved specimen, 7 mm length, NW Pacific, Commander Islands, anterior part of the Radula; E – F, Onchidoris macropompa sp. nov. ZMMU Lc- 37465, living specimen, 15 mm length; E. Close up of cusps of first lateral teeth; F. Few rows enlarged; G – H, Onchidoris muricata (Müller, 1776), ZMMU, not registered, living specimen, 9 mm length, Barents Sea, Dalne-Zelenetskaya Bay, intertidal; G. Middle part of the Radula; H. First lateral teeth enlarged; I. Onchidoris muricata (Müller, 1776), ZMMU, not registered, living specimen, 8 mm length, White Sea, Kandalakshsky Bay, Cape Kartesh, from 5 – 7 m depth. Scale bars: A ― 100 μm, B ― 20 μm, C ― 20 μm, D ― 60 μm, E ― 20 μm, F ― 10 μm, G ― 40 μm, H ― 50 μm, I ― 20 μm. Photos: Alexander Martynov

  • FIGURE 4 in Description of the first cryptobranch onchidoridid Onchimira cavifera gen. et sp. nov., and of three new species of the genera Adalaria Bergh, 1879 and Onchidoris Blainville, 1816 (Nudibranchia: Onchidorididae) from Kamchatka waters
    2018
    Co-Authors: Martynov Alexander, Korshunova Tatiana, Sanamyan Nadezhda, Sanamyan Karen
    Abstract:

    FIGURE 4. Radulae of representatives of the genera Onchimira gen. nov., Calycidoris Abraham, 1876, and Acanthodoris Gray, 1850, scanning electron micrographs. A – C, Onchimira cavifera gen. et sp. nov., paratype ZMMU Lc- 37450, living specimen, 20 mm length; A. Rows toward anterior Radula end; B. Enlarged, showing distinct rows of the small outer lateral teeth; C. Enlarged cusp of two first laterals showing indistinct denticles on the lower tooth; D – E, Acanthodoris uchidai Baba, 1935, preserved specimen, 18 mm length, Kurile Islands, Paramushir Id., depth 20 m; D. Middle rows; E. Details of the first lateral tooth cusp and outer laterals; F. Onchimira cavifera gen. et sp. nov., paratype ZMMU Lc- 37447, living specimen, 18 mm length, three middle rows showing outer laterals; G – I, Calycidoris guentheri Abraham, 1876, ZIN N 40, preserved specimen, 23 mm length; G. Part of the Radula; H. Enlarged two first lateral teeth from the middle rows; I. Part of the Radula; J – K, Onchimira cavifera gen. et sp. nov., paratype ZMMU Lc- 37447, living specimen, 15 mm length; J. Isolated penis; K. Close up of the terminal everted part. Scale bars: A ― 100 μm, B ― 50 μm, C ― 20 μm, D ― 300 μm, E ― 100 μm, F ― 50 μm, G ― 200 μm, H ― 100 μm, I ― 100 μm, J ― 200 μm, K ― 50 μm. Photos: Alexander Martynov