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Chang W, Hale ME. Mechanosensory signal transmission in the arms and the nerve ring, an interarm connective, of Octopus bimaculoides. iScience 2023; 26:106722. [PMID: 37216097 PMCID: PMC10192654 DOI: 10.1016/j.isci.2023.106722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/28/2023] [Accepted: 04/19/2023] [Indexed: 05/24/2023] Open
Abstract
Octopuses coordinate their arms in a range of complex behaviors. In addition to brain-based sensorimotor integration and control, interarm coordination also occurs through a nerve ring at the arms' base. Here, we examine responses to mechanosensory stimulation of the arms by recording neural activity in the stimulated arm, the nerve ring, and other arms in a preparation of only the ring and arms. Arm axial nerve cords show graded responses to mechanosensory input and activity is transmitted proximally and distally in the arm. Mechanostimulation of one arm generates spiking in the nerve ring and in other arms. Activity in the nerve ring decreases with distance from the stimulated arm. Spontaneous activity with a range of spiking patterns occurs in the axial nerve cords and the nerve ring. These data show rich interarm signaling that supports arm control and coordination occurring outside of the brain.
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Affiliation(s)
- Weipang Chang
- Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
| | - Melina E. Hale
- Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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2
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Abstract
We propose an expansion of neuroecological comparisons to include the capabilities of brainless and non-neural organisms. We begin this enterprise by conducting a systematic search for studies on learning in echinoderms. Echinodermata are marine invertebrates comprising starfish, brittle stars, sea cucumbers, sea urchins, and sea lilies. Animals in this phylum lack any centralized brain and instead possess diffuse neural networks known as nerve nets. The learning abilities of these animals are of particular interest as, within the bilaterian clade, they are close evolutionary neighbors to chordates, a phylum whose members exhibit complex feats in learning and contain highly specialized brains. The learning capacities and limitations of echinoderms can inform the evolution of nervous systems and learning in Bilateria. We find evidence of both non-associative and associative learning (in the form of classical conditioning) in echinoderms, which was primarily focused on starfish. Additional evidence of learning is documented in brittle stars, sand dollars, and sea urchins. We then discuss the evolutionary significance of learning capabilities without a brain, the presence of embodied cognition across multiple groups, and compare the learning present in echinoderms with the impressive cognitive abilities documented in the oldest linage group within vertebrates (the major group within the phylum of chordates), fish.
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3
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Lau SCY, Strugnell JM, Sands CJ, Silva CNS, Wilson NG. Evolutionary innovations in Antarctic brittle stars linked to glacial refugia. Ecol Evol 2021; 11:17428-17446. [PMID: 34938519 PMCID: PMC8668817 DOI: 10.1002/ece3.8376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 12/31/2022] Open
Abstract
The drivers behind evolutionary innovations such as contrasting life histories and morphological change are central questions of evolutionary biology. However, the environmental and ecological contexts linked to evolutionary innovations are generally unclear. During the Pleistocene glacial cycles, grounded ice sheets expanded across the Southern Ocean continental shelf. Limited ice-free areas remained, and fauna were isolated from other refugial populations. Survival in Southern Ocean refugia could present opportunities for ecological adaptation and evolutionary innovation. Here, we reconstructed the phylogeographic patterns of circum-Antarctic brittle stars Ophionotus victoriae and O. hexactis with contrasting life histories (broadcasting vs brooding) and morphology (5 vs 6 arms). We examined the evolutionary relationship between the two species using cytochrome c oxidase subunit I (COI) data. COI data suggested that O. victoriae is a single species (rather than a species complex) and is closely related to O. hexactis (a separate species). Since their recent divergence in the mid-Pleistocene, O. victoriae and O. hexactis likely persisted differently throughout glacial maxima, in deep-sea and Antarctic island refugia, respectively. Genetic connectivity, within and between the Antarctic continental shelf and islands, was also observed and could be linked to the Antarctic Circumpolar Current and local oceanographic regimes. Signatures of a probable seascape corridor linking connectivity between the Scotia Sea and Prydz Bay are also highlighted. We suggest that survival in Antarctic island refugia was associated with increase in arm number and a switch from broadcast spawning to brooding in O. hexactis, and propose that it could be linked to environmental changes (such as salinity) associated with intensified interglacial-glacial cycles.
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Affiliation(s)
- Sally C. Y. Lau
- Centre for Sustainable Tropical Fisheries and Aquaculture and College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
| | - Jan M. Strugnell
- Centre for Sustainable Tropical Fisheries and Aquaculture and College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
- Department of Ecology, Environment and EvolutionSchool of Life SciencesLa Trobe UniversityMelbourneVicAustralia
- Securing Antarctica's Environmental FutureJames Cook UniversityTownsvilleQldAustralia
| | - Chester J. Sands
- British Antarctic SurveyNatural Environment Research CouncilCambridgeUK
| | - Catarina N. S. Silva
- Centre for Sustainable Tropical Fisheries and Aquaculture and College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
| | - Nerida G. Wilson
- Collections & ResearchWestern Australian MuseumWelshpoolWAAustralia
- School of Biological SciencesUniversity of Western AustraliaPerthWAAustralia
- Securing Antarctica's Environmental FutureWestern Australian MuseumWelshpoolWAAustralia
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4
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Chappell DR, Horan TM, Speiser DI. Panoramic spatial vision in the bay scallop Argopecten irradians. Proc Biol Sci 2021; 288:20211730. [PMID: 34753355 PMCID: PMC8580434 DOI: 10.1098/rspb.2021.1730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/20/2021] [Indexed: 11/12/2022] Open
Abstract
We have a growing understanding of the light-sensing organs and light-influenced behaviours of animals with distributed visual systems, but we have yet to learn how these animals convert visual input into behavioural output. It has been suggested they consolidate visual information early in their sensory-motor pathways, resulting in them being able to detect visual cues (spatial resolution) without being able to locate them (spatial vision). To explore how an animal with dozens of eyes processes visual information, we analysed the responses of the bay scallop Argopecten irradians to both static and rotating visual stimuli. We found A. irradians distinguish between static visual stimuli in different locations by directing their sensory tentacles towards them and were more likely to point their extended tentacles towards larger visual stimuli. We also found that scallops track rotating stimuli with individual tentacles and with rotating waves of tentacle extension. Our results show, to our knowledge for the first time that scallops have both spatial resolution and spatial vision, indicating their sensory-motor circuits include neural representations of their visual surroundings. Exploring a wide range of animals with distributed visual systems will help us learn the different ways non-cephalized animals convert sensory input into behavioural output.
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Affiliation(s)
- Daniel R. Chappell
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA
| | - Tyler M. Horan
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA
| | - Daniel I. Speiser
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA
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5
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Sumner-Rooney L, Kirwan JD, Lüter C, Ullrich-Lüter E. Run and hide: visual performance in a brittle star. J Exp Biol 2021; 224:jeb236653. [PMID: 34100540 PMCID: PMC8214828 DOI: 10.1242/jeb.236653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 04/12/2021] [Indexed: 11/24/2022]
Abstract
Spatial vision was recently reported in a brittle star, Ophiomastix wendtii, which lacks discrete eyes, but little is known about its visual ecology. Our aim was to better characterize the vision and visual ecology of this unusual visual system. We tested animal orientation relative to vertical bar stimuli at a range of angular widths and contrasts, to identify limits of angular and contrast detection. We also presented dynamic shadow stimuli, either looming towards or passing the animal overhead, to test for potential defensive responses. Finally, we presented animals lacking a single arm with a vertical bar stimulus known to elicit a response in intact animals. We found that O. wendtii orients to large (≥50 deg), high-contrast vertical bar stimuli, consistent with a shelter-seeking role and with photoreceptor acceptance angles estimated from morphology. We calculate poor optical sensitivity for individual photoreceptors, and predict dramatic oversampling for photoreceptor arrays. We also report responses to dark stimuli moving against a bright background - this is the first report of responses to moving stimuli in brittle stars and suggests additional defensive uses for vision in echinoderms. Finally, we found that animals missing a single arm orient less well to static stimuli, which requires further investigation.
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Affiliation(s)
- Lauren Sumner-Rooney
- Oxford University Museum of Natural History, University of Oxford, Parks Road, Oxford OX1 3PW, UK
| | - John D. Kirwan
- Stazione Zoologica Anton Dohrn, Via Francesco Caracciolo, 333, 80122 Naples, Italy
| | - Carsten Lüter
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany
| | - Esther Ullrich-Lüter
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany
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Extraocular Vision in a Brittle Star Is Mediated by Chromatophore Movement in Response to Ambient Light. Curr Biol 2020; 30:319-327.e4. [PMID: 31902727 DOI: 10.1016/j.cub.2019.11.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/27/2019] [Accepted: 11/13/2019] [Indexed: 01/01/2023]
Abstract
Almost all animals can sense light, but only those with spatial vision can "see." Conventionally, this was restricted to animals possessing discrete visual organs (eyes), but extraocular vision could facilitate vision without eyes. Echinoderms form the focus of extraocular vision research [1-7], and the brittle star Ophiocoma wendtii, which exhibits light-responsive color change and shelter seeking, became a key species of interest [4, 8, 9]. Both O. wendtii and an apparently light-indifferent congeneric, O. pumila, possess an extensive network of r-opsin-reactive cells, but its function remains unclear [4]. We show that, although both species are strongly light averse, O. wendtii orients to stimuli necessitating spatial vision for detection, but O. pumila does not. However, O. wendtii's response disappears when chromatophores are contracted within the skeleton. Combining immunohistochemistry, histology, and synchrotron microtomography, we reconstructed models of photoreceptors in situ and extracted estimated angular apertures for O. wendtii and O. pumila. Angular sensitivity estimates, derived from these models, support the hypothesis that chromatophores constitute a screening mechanism in O. wendtii, providing sufficient resolving power to detect the stimuli. RNA sequencing (RNA-seq) identified opsin candidates in both species, including multiple r-opsins and transduction pathway constituents, congruent with immunohistochemistry and studies of other echinoderms [10, 11]. Finally, we note that differing body postures between the two species during experiments may reflect aspect of signal integration. This represents one of the most detailed mechanisms for extraocular vision yet proposed and draws interesting parallels with the only other confirmed extraocular visual system, that of some sea urchins, which also possess chromatophores [1].
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Heydari S, Johnson A, Ellers O, McHenry MJ, Kanso E. Sea star inspired crawling and bouncing. J R Soc Interface 2020; 17:20190700. [PMID: 31910778 PMCID: PMC7014793 DOI: 10.1098/rsif.2019.0700] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/04/2019] [Indexed: 12/11/2022] Open
Abstract
The oral surface of sea stars is lined with arrays of tube feet that enable them to achieve highly controlled locomotion on various terrains. The activity of the tube feet is orchestrated by a nervous system that is distributed throughout the body without a central brain. How such a distributed nervous system produces a coordinated locomotion is yet to be understood. We develop mathematical models of the biomechanics of the tube feet and the sea star body. In the model, the feet are coupled mechanically through their structural connection to a rigid body. We formulate hierarchical control laws that capture salient features of the sea star nervous system. Namely, at the tube foot level, the power and recovery strokes follow a state-dependent feedback controller. At the system level, a directionality command is communicated through the nervous system to all tube feet. We study the locomotion gaits afforded by this hierarchical control model. We find that these minimally coupled tube feet coordinate to generate robust forward locomotion, reminiscent of the crawling motion of sea stars, on various terrains and for heterogeneous tube feet parameters and initial conditions. Our model also predicts a transition from crawling to bouncing consistently with recent experiments. We conclude by commenting on the implications of these findings for understanding the neuromechanics of sea stars and their potential application to autonomous robotic systems.
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Affiliation(s)
- Sina Heydari
- Department of Aerospace and Mechanical Engineering, University of Southern California, 854 Downey Way, Los Angeles, CA 90089, USA
| | - Amy Johnson
- Department of Biology, Bowdoin College, 6500 College Station Brunswick, ME 04011, USA
| | - Olaf Ellers
- Department of Biology, Bowdoin College, 6500 College Station Brunswick, ME 04011, USA
| | - Matthew J. McHenry
- Department of Ecology and Evolutionary Biology, University of California Irvine, 321 Steinhaus Hall, Irvine, CA 92697, USA
| | - Eva Kanso
- Department of Aerospace and Mechanical Engineering, University of Southern California, 854 Downey Way, Los Angeles, CA 90089, USA
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8
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Wakita D, Kagaya K, Aonuma H. A general model of locomotion of brittle stars with a variable number of arms. J R Soc Interface 2020; 17:20190374. [PMID: 31910773 PMCID: PMC7014800 DOI: 10.1098/rsif.2019.0374] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/27/2019] [Indexed: 01/16/2023] Open
Abstract
Typical brittle stars have five radially symmetrical arms that coordinate to move the body in a certain direction. However, some species have a variable number of arms, which is a unique trait since intact animals normally have a fixed number of limbs. How does a single species manage different numbers of appendages for adaptive locomotion? We herein describe locomotion in Ophiactis brachyaspis with four, five, six and seven arms to propose a common rule for the movement of brittle stars with different numbers of arms. For this, we mechanically stimulated one arm of individuals to analyse escape direction and arm movement. By gathering quantitative indices and employing Bayesian statistical modelling, we noted a pattern: regardless of the total number of arms, an anterior position emerges at one of the second neighbouring arms to a mechanically stimulated arm, while arms adjacent to the anterior one synchronously work as left and right rowers. We propose a model in which an afferent signal runs clockwise or anticlockwise along the nerve ring while linearly counting how many arms it passes through. With this model, the question on how 'left and right' emerges in a radially symmetrical body via a decentralized system is answered.
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Affiliation(s)
- Daiki Wakita
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan
| | - Katsushi Kagaya
- The Hakubi Center for Advanced Research, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan
- Seto Marine Biological Laboratory, Field Science, Education and Research Center, Kyoto University, Shirahama, Wakayama 649-2211, Japan
| | - Hitoshi Aonuma
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan
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9
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Kano T, Kanauchi D, Ono T, Aonuma H, Ishiguro A. Flexible Coordination of Flexible Limbs: Decentralized Control Scheme for Inter- and Intra-Limb Coordination in Brittle Stars' Locomotion. Front Neurorobot 2019; 13:104. [PMID: 31920614 PMCID: PMC6923253 DOI: 10.3389/fnbot.2019.00104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 11/29/2019] [Indexed: 11/30/2022] Open
Abstract
Conventional mobile robots have difficulties adapting to unpredictable environments or performing adequately after undergoing physical damages in realtime operation, unlike animals. We address this issue by focusing on brittle stars, an echinoderm related to starfish. Most brittle stars have five flexible arms, and they can coordinate among the arms (i.e., inter-arm coordination) as well as the many bodily degrees of freedom within each arm (i.e., intra-arm coordination). They can move in unpredictable environments while promptly adapting to those, and to their own physical damages (e.g., arm amputation). Our previous work focused on the inter-arm coordination by studying trimmed-arm brittle stars. Herein, we extend our previous work and propose a decentralized control mechanism that enables coupling between the inter-arm and intra-arm coordination. We demonstrate via simulations and real-world experiments with a brittle star-like robot that the behavior of brittle stars when they are intact and undergoing shortening or amputation of arms can be replicated.
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Affiliation(s)
- Takeshi Kano
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Daichi Kanauchi
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Tatsuya Ono
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
| | - Akio Ishiguro
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
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Kano T, Kanauchi D, Aonuma H, Clark EG, Ishiguro A. Decentralized Control Mechanism for Determination of Moving Direction in Brittle Stars With Penta-Radially Symmetric Body. Front Neurorobot 2019; 13:66. [PMID: 31507399 PMCID: PMC6716452 DOI: 10.3389/fnbot.2019.00066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 08/05/2019] [Indexed: 11/16/2022] Open
Abstract
A brittle star, an echinoderm with penta-radially symmetric body, can make decisions about its moving direction and move adapting to various circumstances despite lacking a central nervous system and instead possessing a rather simple distributed nervous system. In this study, we aimed to elucidate the essential control mechanism underlying the determination of moving direction in brittle stars. Based on behavioral findings on brittle stars whose nervous systems were lesioned in various ways, we propose a phenomenological mathematical model. We demonstrate via simulations that the proposed model can well reproduce the behavioral findings. Our findings not only provide insights into the mechanism for the determination of moving direction in brittle stars, but also help understand the essential mechanism underlying autonomous behaviors of animals. Moreover, they will pave the way for developing fully autonomous robots that can make decisions by themselves and move adaptively under various circumstances.
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Affiliation(s)
- Takeshi Kano
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Daichi Kanauchi
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
| | - Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
| | - Elizabeth G Clark
- Department of Geology and Geophysics, Yale University, New Haven, CT, United States
| | - Akio Ishiguro
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
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Formery L, Schubert M, Croce JC. Ambulacrarians and the Ancestry of Deuterostome Nervous Systems. Results Probl Cell Differ 2019; 68:31-59. [PMID: 31598852 DOI: 10.1007/978-3-030-23459-1_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The evolutionary origin and history of metazoan nervous systems has been at the heart of numerous scientific debates for well over a century. This has been a particularly difficult issue to resolve within the deuterostomes, chiefly due to the distinct neural architectures observed within this group of animals. Indeed, deuterosomes feature central nervous systems, apical organs, nerve cords, and basiepidermal nerve nets. Comparative analyses investigating the anatomy and molecular composition of deuterostome nervous systems have nonetheless succeeded in identifying a number of shared and derived features. These analyses have led to the elaboration of diverse theories about the origin and evolutionary history of deuterostome nervous systems. Here, we provide an overview of these distinct theories. Further, we argue that deciphering the adult nervous systems of representatives of all deuterostome phyla, including echinoderms, which have long been neglected in this type of surveys, will ultimately provide answers to the questions concerning the ancestry and evolution of deuterostome nervous systems.
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Affiliation(s)
- Laurent Formery
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Evolution of Intercellular Signaling in Development (EvoInSiDe) Team, Villefranche-sur-Mer, France
| | - Michael Schubert
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Evolution of Intercellular Signaling in Development (EvoInSiDe) Team, Villefranche-sur-Mer, France
| | - Jenifer C Croce
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Evolution of Intercellular Signaling in Development (EvoInSiDe) Team, Villefranche-sur-Mer, France.
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