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Jarva TM, Phillips NM, Von Eiff C, Poulakis GR, Naylor G, Feldheim KA, Flynt AS. Gene expression, evolution, and the genetics of electrosensing in the smalltooth sawfish, Pristis pectinata. Ecol Evol 2024; 14:e11260. [PMID: 38694751 PMCID: PMC11057056 DOI: 10.1002/ece3.11260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 03/14/2024] [Accepted: 03/28/2024] [Indexed: 05/04/2024] Open
Abstract
Sawfishes (Pristidae) are large, highly threatened rays named for their tooth-studded rostrum, which is used for prey sensing and capture. Of all five species, the smalltooth sawfish, Pristis pectinata, has experienced the greatest decline in range, currently found in only ~20% of its historic range. To better understand the genetic underpinnings of these taxonomically and morphologically unique animals, we collected transcriptomic data from several tissue types, mapped them to the recently completed reference genome, and contrasted the patterns observed with comparable data from other elasmobranchs. Evidence of positive selection was detected in 79 genes in P. pectinata, several of which are involved in growth factor/receptor tyrosine kinase signaling and body symmetry and may be related to the unique morphology of sawfishes. Changes in these genes may impact cellular responses to environmental conditions such as temperature, dissolved oxygen, and salinity. Data acquired also allow for examination of the molecular components of P. pectinata electrosensory systems, which are highly developed in sawfishes and have likely been influential in their evolutionary success.
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Affiliation(s)
- Taiya M. Jarva
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Nicole M. Phillips
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Cory Von Eiff
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Gregg R. Poulakis
- Charlotte Harbor Field LaboratoryFish and Wildlife Research Institute, Florida Fish and Wildlife Conservation CommissionPort CharlotteFloridaUSA
| | - Gavin Naylor
- Florida Program for Shark ResearchUniversity of FloridaGainesvilleFloridaUSA
| | - Kevin A. Feldheim
- Pritzker Laboratory for Molecular Systematics and Evolution, the Field MuseumChicagoIllinoisUSA
| | - Alex S. Flynt
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
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2
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Claeson KM, Sidlauskas BL, Troll R, Prescott ZM, Davis EB. From sabers to spikes: A newfangled reconstruction of the ancient, giant, sexually dimorphic Pacific salmon, †Oncorhynchus rastrosus (SALMONINAE: SALMONINI). PLoS One 2024; 19:e0300252. [PMID: 38656950 PMCID: PMC11042722 DOI: 10.1371/journal.pone.0300252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/24/2024] [Indexed: 04/26/2024] Open
Abstract
The impressive †Oncorhynchus rastrosus of the Pacific Northwest's Miocene and Pliocene eras was the largest salmonid ever to live. It sported a hypertrophied premaxilla with a pair of enlarged teeth which the original describers reconstructed as projecting ventrally into the mouth, leading them to assign the species to "Smilodonichthys," a genus now in synonymy. Through CT reconstruction of the holotype and newly collected specimens, we demonstrate that the famed teeth projected laterally like tusks, not ventrally like sabers or fangs. We also expand the original description to characterize sexual dimorphism in mature, breeding individuals. Male and female †Oncorhynchus rastrosus differ in the form of the vomer, rostro-dermethmoid-supraethmoid, and dentary, much as do other extant species of Oncorhynchus. Male specimens possess a more elongate vomer than do females, and female vomers have concave ventral surfaces and prominent median dorsal keels. The dentary of females has no evidence of a kype, though some specimens of †O. rastrosus have a non-uniform density mesial to the tooth bed, which we interpret as a male kype. Unlike extant Oncorhynchus, male and female †O. rastrosus do not differ in premaxilla shape. Because male and females possess hypertrophied premaxillae and lateral premaxillary spikes, the former common name "Sabertoothed Salmon" no longer reflects our understanding of the species' morphology. Accordingly, we redub †O. rastrosus the Spike-Toothed Salmon and postulate that its spikes were multifunctional, serving as defense against predators, in agonism against conspecifics, and as a practical aid to nest construction.
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Affiliation(s)
- Kerin M. Claeson
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, United States of America
| | - Brian L. Sidlauskas
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Ray Troll
- Troll Art Studios, Ketchikan, Alaska, United States of America
| | | | - Edward B. Davis
- Museum of Natural and Cultural History and Department of Earth Sciences, University of Oregon, Eugene, Oregon, United States of America
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3
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Staggl MA, Ruthensteiner B, Straube N. Head anatomy of a lantern shark wet-collection specimen (Chondrichthyes: Etmopteridae). J Anat 2023; 242:872-890. [PMID: 36695312 PMCID: PMC10093163 DOI: 10.1111/joa.13822] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 12/16/2022] [Accepted: 12/23/2022] [Indexed: 01/26/2023] Open
Abstract
In this study, we apply a two-step (untreated and soft tissue stained) diffusible iodine-based contrast-enhanced micro-computed tomography array to a wet-collection Lantern Shark specimen of Etmopterus lucifer. The focus of our scanning approach is the head anatomy. The unstained CT data allow the imaging of mineralized (skeletal) tissue, while results for soft tissue were achieved after staining for 120 h in a 1% ethanolic iodine solution. Three-dimensional visualization after the segmentation of hard as well as soft tissue reveals new details of tissue organization and allows us to draw conclusions on the significance of organs in their function. Outstanding are the ampullae of Lorenzini for electroreception, which appear as the dominant sense along with the olfactory system. Corresponding brain areas of these sensory organs are significantly enlarged as well and likely reflect adaptations to the lantern sharks' deep-sea habitat. While electroreception supports the capture of living prey, the enlarged olfactory system can guide the scavenging of these opportunistic feeders. Compared to other approaches based on the manual dissection of similar species, CT scanning is superior in some but not all aspects. For example, fenestrae of the cranial nerves within the chondrocranium cannot be identified reflecting the limitations of the method, however, CT scanning is less invasive, and the staining is mostly reversible and can be rinsed out.
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Affiliation(s)
- Manuel Andreas Staggl
- Department of Biology II, Ludwig-Maximilians-Universität München, München, Germany.,SNSB-Bavarian State Collection of Zoology, Munich, Germany.,Department of Palaeontology, Faculty of Earth Sciences, Geography and Astronomy, University of Vienna, Vienna, Austria.,Vienna Doctoral School of Ecology and Evolution (VDSEE), University of Vienna, Vienna, Austria
| | | | - Nicolas Straube
- SNSB-Bavarian State Collection of Zoology, Munich, Germany.,Department of Natural History, University Museum of Bergen, Bergen, Norway
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4
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Ding L, Li M, Liu C, Zhou Z, Chen J, Chen X, Chen L, Li J. Study on characteristics of the electric‐field‐sensitive hydrogel inspired by jelly in the ampullae of Lorenzini of elasmobranchs. POLYM ADVAN TECHNOL 2022. [DOI: 10.1002/pat.5820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Laiqian Ding
- Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian China
| | - Mingyang Li
- Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian China
| | - Chong Liu
- Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian China
- Key Laboratory for Precision and Non‐traditional Machining Technology of Ministry of Education Dalian University of Technology Dalian China
| | | | - Jing Chen
- Beijing Spacecrafts Co., Ltd. Beijing China
| | | | - Li Chen
- Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian China
| | - Jingmin Li
- Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian China
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Abrantes K, Barnett A, Soetaert M, Kyne PM, Laird A, Squire L, Seymour J, Wueringer BE, Sleeman J, Huveneers C. Potential of electric fields to reduce bycatch of highly threatened sawfishes. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Sawfishes are among the most threatened families of marine fishes and are susceptible to incidental capture in net fisheries. Since bycatch reduction devices currently used in trawl fisheries are not effective at reducing sawfish catches, new methods to minimise sawfish bycatch are needed. Ideally, these should affect sawfish behaviour and prevent contact with the fishing gear. We tested the effects of electric fields on sawfish behaviour to assess the potential of electric pulses in mitigating sawfish bycatch. Experiments were conducted in a tank where 2 electrodes were suspended in the water column, connected to a pulse generator, and placed across the swimming path of sawfish. Two largetooth sawfish Pristis pristis were tested in control conditions, in the presence of a baseline pulse, and of 5 variations of that pulse where 1 parameter (polarity, voltage, frequency, pulse shape, pulse duration) was altered at a time. Conditional inference trees were used to identify the effects of various parameters (e.g. treatment, individual) on reaction type, reaction distance, twitching presence and duration, and inter-approach times. Sawfish reacted to electric fields, but reaction distances were small (typically <1.2 m), and no field tested consistently led to reactions conducive to escaping from moving nets. The following parameters induced the most response in both individuals: bipolar current, rectangular shaped, 5-10 Hz, ~1500 µs duration, and 100 V. We recommend further research focussing on moving nets, testing a V-shaped electric array preceding the net mouth by at least 5 m, and testing a setup similar to electrotrawling.
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Affiliation(s)
- K Abrantes
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
- Biopixel Oceans Foundation, Cairns, Qld 4870, Australia
| | - A Barnett
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
- Biopixel Oceans Foundation, Cairns, Qld 4870, Australia
| | - M Soetaert
- Institute for Agricultural and Fisheries Research, Animal Sciences - Fisheries, Ankerstraat 1, 8400 Oostende, Belgium
| | - PM Kyne
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0815, Australia
| | - A Laird
- Northern Prawn Fishery Industry Pty Ltd, Caloundra, Qld 4551, Australia
| | - L Squire
- Cairns Marine, Cairns, Qld 4870, Australia
| | - J Seymour
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Qld 4870, Australia
| | - BE Wueringer
- Sharks and Rays Australia, PO Box 575, Bungalow, Cairns, Qld 4870, Australia
| | - J Sleeman
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Qld 4870, Australia
| | - C Huveneers
- College of Science and Engineering, Flinders University, Bedford Park, Adelaide, SA 5042, Australia
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Melrose J, Hayes AJ, Bix G. The CNS/PNS Extracellular Matrix Provides Instructive Guidance Cues to Neural Cells and Neuroregulatory Proteins in Neural Development and Repair. Int J Mol Sci 2021; 22:5583. [PMID: 34070424 PMCID: PMC8197505 DOI: 10.3390/ijms22115583] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The extracellular matrix of the PNS/CNS is unusual in that it is dominated by glycosaminoglycans, especially hyaluronan, whose space filling and hydrating properties make essential contributions to the functional properties of this tissue. Hyaluronan has a relatively simple structure but its space-filling properties ensure micro-compartments are maintained in the brain ultrastructure, ensuring ionic niches and gradients are maintained for optimal cellular function. Hyaluronan has cell-instructive, anti-inflammatory properties and forms macro-molecular aggregates with the lectican CS-proteoglycans, forming dense protective perineuronal net structures that provide neural and synaptic plasticity and support cognitive learning. AIMS To highlight the central nervous system/peripheral nervous system (CNS/PNS) and its diverse extracellular and cell-associated proteoglycans that have cell-instructive properties regulating neural repair processes and functional recovery through interactions with cell adhesive molecules, receptors and neuroregulatory proteins. Despite a general lack of stabilising fibrillar collagenous and elastic structures in the CNS/PNS, a sophisticated dynamic extracellular matrix is nevertheless important in tissue form and function. CONCLUSIONS This review provides examples of the sophistication of the CNS/PNS extracellular matrix, showing how it maintains homeostasis and regulates neural repair and regeneration.
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Affiliation(s)
- James Melrose
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia
- Sydney Medical School, Northern, The University of Sydney, Sydney, NSW 2052, Australia
- Faculty of Medicine and Health, The University of Sydney, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
| | - Anthony J. Hayes
- Bioimaging Research Hub, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK;
| | - Gregory Bix
- Clinical Neuroscience Research Center, Departments of Neurosurgery and Neurology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
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Wueringer BE, Winther-Janson M, Raoult V, Guttridge TL. Anatomy of the mechanosensory lateral line canal system and electrosensory ampullae of Lorenzini in two species of sawshark (fam. Pristiophoridae). JOURNAL OF FISH BIOLOGY 2021; 98:168-177. [PMID: 33006147 DOI: 10.1111/jfb.14567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 08/24/2020] [Accepted: 09/29/2020] [Indexed: 06/11/2023]
Abstract
It has long been assumed that the elongated rostra (the saws) of sawsharks (family: Pristiophoridae) and sawfish (family: Pristidae) serve a similar function. Recent behavioural and anatomical studies have shed light on the dual function of the pristid rostrum in mechanosensory and electrosensory prey detection and prey manipulation. Here, the authors examine the distributions of the mechanosensory lateral line canals and electrosensory ampullae of Lorenzini in the southern sawshark, Pristiophorus nudipinnis and the longnose sawshark, Pristiophorus cirratus. In both species, the receptive fields of the mechano- and electrosensory systems extend the full length of the rostrum indicating that the sawshark rostrum serves a sensory function. Interestingly, despite recent findings suggesting they feed at different trophic levels, minimal interspecific variation between the two species was recorded. Nonetheless, compared to pristids, the pristiophorid rostrum possesses a reduced mechanosensory sampling field but higher electrosensory resolution, which suggests that pristiophorids may not use their rostrums to disable large prey like pristids do.
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Affiliation(s)
- Barbara E Wueringer
- Sharks And Rays Australia, Bungalow, Queensland, Australia
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | | | - Vincent Raoult
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
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8
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Paulin MG, Cahill‐Lane J. Events in Early Nervous System Evolution. Top Cogn Sci 2019; 13:25-44. [DOI: 10.1111/tops.12461] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 12/20/2022]
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9
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Melrose J. Functional Consequences of Keratan Sulfate Sulfation in Electrosensory Tissues and in Neuronal Regulation. ACTA ACUST UNITED AC 2019; 3:e1800327. [PMID: 32627425 DOI: 10.1002/adbi.201800327] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/16/2019] [Indexed: 12/20/2022]
Abstract
Keratan sulfate (KS) is a functional electrosensory and neuro-instructive molecule. Recent studies have identified novel low sulfation KS in auditory and sensory tissues such as the tectorial membrane of the organ of Corti and the Ampullae of Lorenzini in elasmobranch fish. These are extremely sensitive proton gradient detection systems that send signals to neural interfaces to facilitate audition and electrolocation. High and low sulfation KS have differential functional roles in song learning in the immature male zebra song-finch with high charge density KS in song nuclei promoting brain development and cognitive learning. The conductive properties of KS are relevant to the excitable neural phenotype. High sulfation KS interacts with a large number of guidance and neuroregulatory proteins. The KS proteoglycan microtubule associated protein-1B (MAP1B) stabilizes actin and tubulin cytoskeletal development during neuritogenesis. A second 12 span transmembrane synaptic vesicle associated KS proteoglycan (SV2) provides a smart gel storage matrix for the storage of neurotransmitters. MAP1B and SV2 have prominent roles to play in neuroregulation. Aggrecan and phosphacan have roles in perineuronal net formation and in neuroregulation. A greater understanding of the biology of KS may be insightful as to how neural repair might be improved.
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Affiliation(s)
- James Melrose
- Raymond Purves Bone and Joint Research Laboratories, Kolling Institute of Medical Research, Royal North Shore Hospital and University of Sydney, St. Leonards, NSW, 2065, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.,Sydney Medical School, Northern, Sydney University, Royal North Shore Hospital, St. Leonards, NSW, 2065, Australia.,Faculty of Medicine and Health, University of Sydney, Royal North Shore Hospital, St. Leonards, NSW, 2065, Australia
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10
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Gidmark NJ, Pos K, Matheson B, Ponce E, Westneat MW. Functional Morphology and Biomechanics of Feeding in Fishes. FEEDING IN VERTEBRATES 2019. [DOI: 10.1007/978-3-030-13739-7_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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11
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Rangel BS, Wosnick N, Amorim AF, K Junior JR, Rici REG. Microscopic aspects of electrosensory system on the partially euryhaline lesser guitarfish. AN ACAD BRAS CIENC 2017; 90:37-39. [PMID: 29236865 DOI: 10.1590/0001-3765201720150889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/18/2016] [Indexed: 11/22/2022] Open
Abstract
The electrosensory system on elasmobranchs consists of subcutaneous electroreceptor organs known as ampullae of Lorenzini. The present study investigated the ampullae of Lorenzini morphology of the lesser guitarfish Zapteryx brevirostris, using light microscopy and scanning electron microscopy. The pore number found in the ventral skin surface is much higher than that found in the dorsal portion, characteristic of species that inhabit the euphotic zone. Under light microscopy it was possible to observe that the wall canal consists of a single layer of squamous epithelial cells. The canal features distal expansion, where the ampullae are located with up to six alveoli. The sensory epithelium of ampullae is composed by cubic cells, with oval nucleus, restricted to the interior of the alveoli. With analysis the clusters under scanning electron microscopy, it was possible to observe the structure and the random arrangement of individual ampullae, canals and nerves. The distribution of dorsal and ventral pores and ampullae in Z. brevirostris resembled those of the same family. The number of alveoli per ampullae was similar to that found in euryhaline elasmobranchs species, suggesting that the morphological organization in Z. brevirostris is linked to its possible evolutionary transitory position among batoids.
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Affiliation(s)
- Bianca S Rangel
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, 321, 05508-090 São Paulo, SP, Brazil.,Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Rua Professor Orlando Marques Paiva, s/n, 05508-270 São Paulo, SP, Brazil
| | - Natascha Wosnick
- Departamento de Fisiologia, Setor de Ciências Biológicas, Centro Politécnico, Universidade Federal do Paraná, Av. Coronel Francisco Heráclito dos Santos, s/n, Jardim das Américas, 81531-990 Curitiba, PR, Brazil
| | - Alberto F Amorim
- Núcleo de Pesquisa e Desenvolvimento, Instituto de Pesca, Agência Paulista de Tecnologia dos Agronegócios, Secretaria de Agricultura e Abastecimento do Estado de São Paulo, Av. Bartolomeu de Gusmão, 192, 11030-906 Santos, SP, Brazil
| | - José Roberto K Junior
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Rua Professor Orlando Marques Paiva, s/n, 05508-270 São Paulo, SP, Brazil
| | - Rose E G Rici
- Central de Facilidades à Pesquisa, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Rua Professor Orlando Marques Paiva, s/n, 05508-270 São Paulo, SP, Brazil
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Vullo R, Guinot G. Denticle-embedded ampullary organs in a Cretaceous shark provide unique insight into the evolution of elasmobranch electroreceptors. Naturwissenschaften 2015; 102:65. [PMID: 26420508 DOI: 10.1007/s00114-015-1315-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/13/2015] [Accepted: 09/17/2015] [Indexed: 11/29/2022]
Abstract
Here, we report a novel type of dermal denticle (or placoid scale), unknown among both living and fossil chondrichthyan fishes, in a Cretaceous lamniform shark. By their morphology and location, these dermal denticles, grouped into clusters in the cephalic region, appear to have been directly associated with the electrosensory ampullary system. These denticles have a relatively enlarged (∼350 μm in diameter), ornamented crown with a small (∼100 μm) asterisk- or cross-shaped central perforation connected to a multi-alveolate internal cavity. The formation of such a complex structure can be explained by the annular coalescence and fusion, around an ampullary vesicle, of several developmental units still at papillary stage (i.e. before mineralization), leading to a single denticle embedding an alveolar ampulla devoid of canal. This differs from larger typical ampullae of Lorenzini with a well-developed canal opening in a pore of the skin and may represent another adaptive response to low skin resistance. Since it has been recently demonstrated that ampullary organs arise from lateral line placodes in chondrichthyans, this highly specialized type of dermal denticle (most likely non-deciduous) may be derived from the modified placoid scales covering the superficial neuromasts (pit organs) of the mechanosensory lateral line system of many modern sharks.
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Affiliation(s)
- Romain Vullo
- Géosciences Rennes, UMR CNRS 6118, Université de Rennes 1, 35042, Rennes, France.
| | - Guillaume Guinot
- Département de Géologie et Paléontologie, Muséum d'Histoire Naturelle de Genève, CP 6434, 1211, Geneva 6, Switzerland
- Institut des Sciences de l'Evolution, UMR CNRS 5554, Université de Montpellier, 34095, Montpellier, France
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13
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Effects of an electric field on white sharks: in situ testing of an electric deterrent. PLoS One 2013; 8:e62730. [PMID: 23658766 PMCID: PMC3642219 DOI: 10.1371/journal.pone.0062730] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 03/24/2013] [Indexed: 11/22/2022] Open
Abstract
Elasmobranchs can detect minute electromagnetic fields, <1 nVcm–1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.
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14
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Collin SP. The Neuroecology of Cartilaginous Fishes: Sensory Strategies for Survival. BRAIN, BEHAVIOR AND EVOLUTION 2012; 80:80-96. [DOI: 10.1159/000339870] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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