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Smart sharks: a review of chondrichthyan cognition. Anim Cogn 2023; 26:175-188. [PMID: 36394656 PMCID: PMC9877065 DOI: 10.1007/s10071-022-01708-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 10/16/2022] [Accepted: 10/20/2022] [Indexed: 11/19/2022]
Abstract
450 million years of evolution have given chondrichthyans (sharks, rays and allies) ample time to adapt perfectly to their respective everyday life challenges and cognitive abilities have played an important part in that process. The diversity of niches that sharks and rays occupy corresponds to matching diversity in brains and behaviour, but we have only scratched the surface in terms of investigating cognition in this important group of animals. The handful of species that have been cognitively assessed in some detail over the last decade have provided enough data to safely conclude that sharks and rays are cognitively on par with most other vertebrates, including mammals and birds. Experiments in the lab as well as in the wild pose their own unique challenges, mainly due to the handling and maintenance of these animals as well as controlling environmental conditions and elimination of confounding factors. Nonetheless, significant advancements have been obtained in the fields of spatial and social cognition, discrimination learning, memory retention as well as several others. Most studies have focused on behaviour and the underlying neural substrates involved in cognitive information processing are still largely unknown. Our understanding of shark cognition has multiple practical benefits for welfare and conservation management but there are obvious gaps in our knowledge. Like most marine animals, sharks and rays face multiple threats. The effects of climate change, pollution and resulting ecosystem changes on the cognitive abilities of sharks and stingrays remain poorly investigated and we can only speculate what the likely impacts might be based on research on bony fishes. Lastly, sharks still suffer from their bad reputation as mindless killers and are heavily targeted by commercial fishing operations for their fins. This public relations issue clouds people's expectations of shark intelligence and is a serious impediment to their conservation. In the light of the fascinating results presented here, it seems obvious that the general perception of sharks and rays as well as their status as sentient, cognitive animals, needs to be urgently revisited.
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Naisbett-Jones LC, Lohmann KJ. Magnetoreception and magnetic navigation in fishes: a half century of discovery. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:19-40. [PMID: 35031832 DOI: 10.1007/s00359-021-01527-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/15/2023]
Abstract
As the largest and most diverse vertebrate group on the planet, fishes have evolved an impressive array of sensory abilities to overcome the challenges associated with navigating the aquatic realm. Among these, the ability to detect Earth's magnetic field, or magnetoreception, is phylogenetically widespread and used by fish to guide movements over a wide range of spatial scales ranging from local movements to transoceanic migrations. A proliferation of recent studies, particularly in salmonids, has revealed that fish can exploit Earth's magnetic field not only as a source of directional information for maintaining consistent headings, but also as a kind of map for determining location at sea and for returning to natal areas. Despite significant advances, much about magnetoreception in fishes remains enigmatic. How fish detect magnetic fields remains unknown and our understanding of the evolutionary origins of vertebrate magnetoreception would benefit greatly from studies that include a wider array of fish taxa. The rich diversity of life-history characteristics that fishes exhibit, the wide variety of environments they inhabit, and their suitability for manipulative studies, make fishes promising subjects for magnetoreception studies.
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Affiliation(s)
| | - Kenneth J Lohmann
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599, USA
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3
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Keller BA, Putman NF, Grubbs RD, Portnoy DS, Murphy TP. Map-like use of Earth's magnetic field in sharks. Curr Biol 2021; 31:2881-2886.e3. [PMID: 33961785 DOI: 10.1016/j.cub.2021.03.103] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 02/25/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Migration is common in marine animals,1-5 and use of the map-like information of Earth's magnetic field appears to play an important role.2,6-9 While sharks are iconic migrants10-12 and well known for their sensitivity to electromagnetic fields,13-20 whether this ability is used for navigation is unresolved.14,17,21,22 We conducted magnetic displacement experiments on wild-caught bonnetheads (Sphyrna tiburo) and show that magnetic map cues can elicit homeward orientation. We further show that use of a magnetic map to derive positional information may help explain aspects of the genetic structure of bonnethead populations in the northwest Atlantic.23-26 These results offer a compelling explanation for the puzzle of how migratory routes and population structure are maintained in marine environments, where few physical barriers limit movements of vagile species. VIDEO ABSTRACT.
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Affiliation(s)
- Bryan A Keller
- Florida State University Coastal and Marine Laboratory, 3618 Coastal Highway 98, St. Teresa, FL 32358, USA.
| | - Nathan F Putman
- LGL Ecological Research Associates, 4103 South Texas Avenue, Suite 211, Bryan, TX 77802, USA
| | - R Dean Grubbs
- Florida State University Coastal and Marine Laboratory, 3618 Coastal Highway 98, St. Teresa, FL 32358, USA
| | - David S Portnoy
- Marine Genomics Laboratory, Texas A&M University, Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Timothy P Murphy
- Florida State University, National High Magnetic Field Laboratory, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA
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4
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Electrosensory Impairment in the Atlantic Stingray, Hypanus sabinus, After Crude Oil Exposure. ZOOLOGY 2020; 143:125844. [PMID: 33130491 DOI: 10.1016/j.zool.2020.125844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 08/04/2020] [Accepted: 09/08/2020] [Indexed: 11/24/2022]
Abstract
Elasmobranchs are renowned for their extremely sensitive electrosensory system, which is used to detect predators, prey, and mates, and is possibly used for navigation. The proper functioning of the electrosensory system is thus critical to fitness. The objective of this study was to test whether exposure to crude oil impairs the electroreceptive capabilities of elasmobranch fishes. Electrosensory function was quantified from six stingrays before and after exposure to a concentration of oil that mimicked empirically measured concentrations along the coast of Louisiana following the Deepwater Horizon spill. Orientation distance (cm), and angle with respect to the dipole axis of a prey-simulating electric field were used to derive the electric field intensity that elicited a response. Oil exposed stingrays continued to exhibit feeding behavior, but they initiated orientations to prey-simulating electric fields from a significantly closer orientation distance. The mean orientation distance after oil exposure was 5.29 ± 0.41 SE cm compared to a pre-exposure orientation distance of 7.16 ± 0.66 SE cm. Stingrays required a mean electric field intensity of 0.596 ± 0.21 SE μV cm-1 to initiate a response after oil exposure, compared to a mean of only 0.127 ± 0.03 SE μV cm-1 in uncontaminated seawater. Oil exposed stingrays thus exhibited a response to a stimulus approximately 4.7 times greater than controls. Stingrays impacted by an oil spill appear to experience reduced electrosensory capabilities, which could detrimentally impact fitness. This study is the first to quantify the effects of crude oil on behavioral electrosensory function.
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Heinrich DDU, Vila Pouca C, Brown C, Huveneers C. Effects of reward magnitude and training frequency on the learning rates and memory retention of the Port Jackson shark Heterodontus portusjacksoni. Anim Cogn 2020; 23:939-949. [PMID: 32524291 DOI: 10.1007/s10071-020-01402-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 12/26/2022]
Abstract
The development of adaptive responses to novel situations via learning has been demonstrated in a wide variety of animal taxa. However, knowledge on the learning abilities of one of the oldest extant vertebrate groups, Chondrichthyes, remains limited. With the increasing interest in global wildlife tourism and shark feeding operations, it is important to understand the capacities of these animals to form associations between human activities and food. We used an operant conditioning regime with a simple spatial cognitive task to investigate the effects of reinforcement frequency and reward magnitude on the learning performance and memory retention of Port Jackson sharks (Heterodontus portusjacksoni). Twenty-four Port Jackson sharks were assigned one of four treatments differing in reward magnitude and reinforcement frequency (large magnitude-high frequency; large magnitude-low frequency; small magnitude-high frequency; small magnitude-low frequency). The sharks were trained over a 21-day period to compare the number of days that it took to learn to pass an assigned door to feed. Sharks trained at a high reinforcement frequency demonstrated faster learning rates and a higher number of passes through the correct door at the end of the trials, while reward magnitude had limited effects on learning rate. This suggests that a reduction in reinforcement frequency during tourism-related feeding operations is likely to be more effective in reducing the risk of sharks making associations with food than limiting the amount of food provided.
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Affiliation(s)
- Dennis D U Heinrich
- College of Science and Engineering, Flinders University, Sturt Road, Adelaide, SA, Australia.
| | - Catarina Vila Pouca
- Zoological Institute, Stockholm University, 10691, Stockholm, Sweden.,Behavioural Ecology Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Culum Brown
- Department of Biological Sciences, Macquarie University, Innovation Drive, Sydney, NSW, Australia
| | - Charlie Huveneers
- College of Science and Engineering, Flinders University, Sturt Road, Adelaide, SA, Australia
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Lyons K, Bigman JS, Kacev D, Mull CG, Carlisle AB, Imhoff JL, Anderson JM, Weng KC, Galloway AS, Cave E, Gunn TR, Lowe CG, Brill RW, Bedore CN. Bridging disciplines to advance elasmobranch conservation: applications of physiological ecology. CONSERVATION PHYSIOLOGY 2019; 7:coz011. [PMID: 31110763 PMCID: PMC6519003 DOI: 10.1093/conphys/coz011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/02/2019] [Accepted: 03/19/2019] [Indexed: 06/09/2023]
Abstract
A strength of physiological ecology is its incorporation of aspects of both species' ecology and physiology; this holistic approach is needed to address current and future anthropogenic stressors affecting elasmobranch fishes that range from overexploitation to the effects of climate change. For example, physiology is one of several key determinants of an organism's ecological niche (along with evolutionary constraints and ecological interactions). The fundamental role of physiology in niche determination led to the development of the field of physiological ecology. This approach considers physiological mechanisms in the context of the environment to understand mechanistic variations that beget ecological trends. Physiological ecology, as an integrative discipline, has recently experienced a resurgence with respect to conservation applications, largely in conjunction with technological advances that extended physiological work from the lab into the natural world. This is of critical importance for species such as elasmobranchs (sharks, skates and rays), which are an especially understudied and threatened group of vertebrates. In 2017, at the American Elasmobranch Society meeting in Austin, Texas, the symposium entitled `Applications of Physiological Ecology in Elasmobranch Research' provided a platform for researchers to showcase work in which ecological questions were examined through a physiological lens. Here, we highlight the research presented at this symposium, which emphasized the strength of linking physiological tools with ecological questions. We also demonstrate the applicability of using physiological ecology research as a method to approach conservation issues, and advocate for a more available framework whereby results are more easily accessible for their implementation into management practices.
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Affiliation(s)
- K Lyons
- Georgia Aquarium, Atlanta, GA, USA
| | - J S Bigman
- Simon Fraser University, Burnaby, Canada
| | - D Kacev
- Southwest Fisheries Science Center, La Jolla, CA, USA
| | - C G Mull
- Simon Fraser University, Burnaby, Canada
| | | | - J L Imhoff
- Florida State University Coastal and Marine Laboratory, St. Teresa, FL, USA
| | - J M Anderson
- University of Hawai`i at Mānoa, Honolulu, HI, USA
| | - K C Weng
- Virginia Institute of Marine Science, Gloucester Point, VA, USA
| | - A S Galloway
- South Carolina Department of Natural Resources, SC, USA
| | - E Cave
- Florida Atlantic University, Boca Raton, FL, USA
| | - T R Gunn
- Georgia Southern University, Statesboro, GA USA
| | - C G Lowe
- California State University Long Beach, Long Beach, CA, USA
| | - R W Brill
- Virginia Institute of Marine Science, Gloucester Point, VA, USA
| | - C N Bedore
- Georgia Southern University, Statesboro, GA USA
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Martini S, Begall S, Findeklee T, Schmitt M, Malkemper EP, Burda H. Dogs can be trained to find a bar magnet. PeerJ 2018; 6:e6117. [PMID: 30588405 PMCID: PMC6301327 DOI: 10.7717/peerj.6117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/13/2018] [Indexed: 11/20/2022] Open
Abstract
Magnetoreception, the ability to sense the Earth’s magnetic field (MF), is a widespread phenomenon in the animal kingdom. In 1966, the first report on a magnetosensitive vertebrate, the European robin (Erithacus rubecula), was published. After that, numerous further species of different taxa have been identified to be magnetosensitive as well. Recently, it has been demonstrated that domestic dogs (Canis lupus familiaris) prefer to align their body axis along the North–South axis during territorial marking under calm MF conditions and that they abandon this preference when the Earth’s MF is unstable. In a further study conducting a directional two-choice-test, dogs showed a spontaneous preference for the northern direction. Being designated as putatively magnetosensitive and being also known as trainable for diverse choice and search tests, dogs seem to be suitable model animals for a direct test of magnetoreception: learning to find a magnet. Using operant conditioning dogs were trained to identify the MF of a bar magnet in a three-alternative forced-choice experiment. We excluded visual cues and used control trials with food treats to test for the role of olfaction in finding the magnet. While 13 out of 16 dogs detected the magnet significantly above chance level (53–73% success rate), none of the dogs managed to do so in finding the food treat (23–40% success rate). In a replication of the experiment under strictly blinded conditions five out of six dogs detected the magnet above chance level (53–63% success rate). These experiments support the existence of a magnetic sense in domestic dogs. Whether the sense enables dogs to perceive MFs as weak as the Earth’s MF, if they use it for orientation, and by which mechanism the fields are perceived remain open questions.
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Affiliation(s)
- Sabine Martini
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Sabine Begall
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.,Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
| | | | - Marcus Schmitt
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - E Pascal Malkemper
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.,Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
| | - Hynek Burda
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.,Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
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9
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Insight into shark magnetic field perception from empirical observations. Sci Rep 2017; 7:11042. [PMID: 28887553 PMCID: PMC5591188 DOI: 10.1038/s41598-017-11459-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/24/2017] [Indexed: 12/31/2022] Open
Abstract
Elasmobranch fishes are among a broad range of taxa believed to gain positional information and navigate using the earth’s magnetic field, yet in sharks, much remains uncertain regarding the sensory receptors and pathways involved, or the exact nature of perceived stimuli. Captive sandbar sharks, Carcharhinus plumbeus were conditioned to respond to presentation of a magnetic stimulus by seeking out a target in anticipation of reward (food). Sharks in the study demonstrated strong responses to magnetic stimuli, making significantly more approaches to the target (p = < 0.01) during stimulus activation (S+) than before or after activation (S−). Sharks exposed to reversible magnetosensory impairment were less capable of discriminating changes to the local magnetic field, with no difference seen in approaches to the target under the S+ and S− conditions (p = 0.375). We provide quantified detection and discrimination thresholds of magnetic stimuli presented, and quantify associated transient electrical artefacts. We show that the likelihood of such artefacts serving as the stimulus for observed behavioural responses was low. These impairment experiments support hypotheses that magnetic field perception in sharks is not solely performed via the electrosensory system, and that putative magnetoreceptor structures may be located in the naso-olfactory capsules of sharks.
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