Current Search: Animal navigation (x)
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- Title
- Sun compass orientation in juvenile green sea turtles (Chelonia mydas).
- Creator
- Mott, Cody Robert., Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Recent studies show that sea turtles use both magnetic and visual cues to successfully orient. Juvenile green sea turtles from the near shore reefs of Palm Beach County, Florida were brought to the lab to determine whether the sun could serve as a visual orientation cue. When tethered during the day in a large outdoor tank west of the ocean, the turtles oriented east to northeast. To determine whether the sun's position was used to maintain their heading, I altered the turtles' perception of...
Show moreRecent studies show that sea turtles use both magnetic and visual cues to successfully orient. Juvenile green sea turtles from the near shore reefs of Palm Beach County, Florida were brought to the lab to determine whether the sun could serve as a visual orientation cue. When tethered during the day in a large outdoor tank west of the ocean, the turtles oriented east to northeast. To determine whether the sun's position was used to maintain their heading, I altered the turtles' perception of time by entraining them to a light cycle advanced by 7 h relative to the natural cycle. When tested afterward in the same outdoor tank the turtles oriented northwest, the predicted direction after compensating for the sun's movement over 7 h across the sky. Orientation was unchanged when the turtles bore magnets that negated the use of magnetic cues. These results are consistent with the hypothesis that the turtles used the sun for orientation.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2705073
- Subject Headings
- Animal orientation, Adaptation (Biology), Animal navigation, Sea turtles, Migration
- Format
- Document (PDF)
- Title
- Endogenous programs and the development of sea-finding orientation of loggerhead hatchlings (Caretta caretta).
- Creator
- Barrett, Christie A., Florida Atlantic University, Salmon, Michael
- Abstract/Description
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This study's objective was to determine if the transfer of a crawling direction to a magnetic compass in loggerhead hatchling sea turtles ( Caretta caretta L.) was facilitated by how long the turtle crawled (an "endogenous timing" component). I first determined how long it took hatchlings to crawl from their nest to the ocean. Two types of experiments were then carried out. In the first, crawling time varied. In the second, both crawling time and direction varied. I found that at most beaches...
Show moreThis study's objective was to determine if the transfer of a crawling direction to a magnetic compass in loggerhead hatchling sea turtles ( Caretta caretta L.) was facilitated by how long the turtle crawled (an "endogenous timing" component). I first determined how long it took hatchlings to crawl from their nest to the ocean. Two types of experiments were then carried out. In the first, crawling time varied. In the second, both crawling time and direction varied. I found that at most beaches hatchlings crawled to the ocean in less than 5 min. My experiments showed that if crawls are too short (1 min), or too long (5 min), vector transfer is weakened compared to a 2 min crawl. I also found that a period of non-directional crawling interfered with the ability of a 2 min crawl to promote calibration. These results confirm that efficient transfer of a crawling vector, maintained by visual compass, to a swimming vector, maintained by a magnetic compass, depends upon an endogenous timing program in hatchlings. The temporal properties of that program are, in turn, apparently shaped by where their mothers place nests on the beach.
Show less - Date Issued
- 2004
- PURL
- http://purl.flvc.org/fcla/dt/13175
- Subject Headings
- Animal orientation, Animal navigation, Sea turtles--Orientation, Loggerhead turtle
- Format
- Document (PDF)
- Title
- Heading in the right direction: the behavior and brain mechanisms of directional navigation.
- Creator
- Williams, Sidney Beth., Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
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The mechanisms that rodents employ to navigate through their environment have been greatly studied. Cognitive mapping theory suggests that animals use distal cues in the environment to navigate to a goal location (place navigation). However, others have found that animals navigate in a particular direction to find a goal (directional navigation). The rodent brain contains head direction cells (HD cells) that discharge according to the head direction of the animal. Navigation by heading...
Show moreThe mechanisms that rodents employ to navigate through their environment have been greatly studied. Cognitive mapping theory suggests that animals use distal cues in the environment to navigate to a goal location (place navigation). However, others have found that animals navigate in a particular direction to find a goal (directional navigation). The rodent brain contains head direction cells (HD cells) that discharge according to the head direction of the animal. Navigation by heading direction is disrupted by lesions of the anterodorsal thalamic nuclei (ADN), many of which are HD cells. Aim 1 tested whether male C57BL/6J mice exhibit direction or place navigation in the Morris water maze. Aim 2 tested the effects of temporary inactivation of the ADN on directional navigation. Together, these data indicate that C57BL/6J mice also exhibit preference for directional navigation and suggest that the ADN may be crucial for this form of spatial navigation.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/186774
- Subject Headings
- Mice as laboratory animals, Animal navigation, Spatial behavior in animals, Cognition in animals
- Format
- Document (PDF)
- Title
- Visual Adaptations of Ontogenetically Migrating Deep-Sea Crustaceans.
- Creator
- Whitehill, Elizabeth A. G., Frank, Tamara M., Florida Atlantic University
- Abstract/Description
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Species that are ontogenetic migrators have early life stages (juveniles) that live shallower in the water column than the adults and therefore experience a brighter environment than the adults. This work provides evidence that juveniles and adults of the ontogenetically migrating crustacean species Gnathophausia ingens, Oplophorus gracilirostris, and Systellaspis debilis have evolved visual adaptations to their respective environments. The juveniles use apposition optics that provide greater...
Show moreSpecies that are ontogenetic migrators have early life stages (juveniles) that live shallower in the water column than the adults and therefore experience a brighter environment than the adults. This work provides evidence that juveniles and adults of the ontogenetically migrating crustacean species Gnathophausia ingens, Oplophorus gracilirostris, and Systellaspis debilis have evolved visual adaptations to their respective environments. The juveniles use apposition optics that provide greater resolution, whereas the adults use superposition optics that maximize sensitivity. These animals also have regional specializations to aid in viewing a light field that is brighter above than below, such as accessory screening pigments located dorsally and superposition type optics ventrally. The non-ontogenetic migrators Notostomus elegans and Notostomus gibbosus possess superposition optics as both juveniles and adults, implying that the changes seen in ontogenetic migrators are indeed visual adaptations.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00000854
- Subject Headings
- Animal navigation, Deep-sea biology, Shellfish fisheries, Spectral sensitivity
- Format
- Document (PDF)
- Title
- The magnetic compass of the loggerhead sea turtle (Caretta caretta L.): Can surface waves establish magnetic directional preference?.
- Creator
- Goff, Matthew Douglas, Florida Atlantic University, Salmon, Michael
- Abstract/Description
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Hatchling loggerhead sea turtles emerge from their nests on oceanic beaches, crawl to the surf zone, and swim out to sea. How do turtles maintain oriented headings once they lose contact with land? I tested the hypothesis that by swimming into surface waves hatchlings establish an offshore heading (directional preference), and that once out to sea this heading is transferred to, and maintained by, a magnetic compass. This hypothesis was supported by laboratory and field experiments, described...
Show moreHatchling loggerhead sea turtles emerge from their nests on oceanic beaches, crawl to the surf zone, and swim out to sea. How do turtles maintain oriented headings once they lose contact with land? I tested the hypothesis that by swimming into surface waves hatchlings establish an offshore heading (directional preference), and that once out to sea this heading is transferred to, and maintained by, a magnetic compass. This hypothesis was supported by laboratory and field experiments, described herein. A directional preference can also be established by oriented crawling (from the nest to the surf zone). Thus hatchlings possess two mechanisms (crawling and swimming) for the establishment of an offshore heading. The use of these alternative mechanisms probably assures that turtles escape from shore under the broad range of conditions which they naturally encounter after emerging from their nests.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15285
- Subject Headings
- Loggerhead turtle, Sea turtles--Orientation, Animal navigation
- Format
- Document (PDF)
- Title
- The orientation and survival of loggerhead sea turtle hatchlings (Caretta caretta L.) in the nearshore environment.
- Creator
- Glenn, Lawrence, Florida Atlantic University, Salmon, Michael, Wyneken, Jeanette
- Abstract/Description
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Hatchling sea turtles emerge at night from underground nests, crawl to the ocean, and swim out to sea. In this study, I determined how offshore orientation and shallow-water predation rates varied under natural (sand bottom and patch reef) and modified (submerged breakwater and open-beach hatchery) ecological circumstances. Hatchling offshore orientation in the sea was normal under all conditions; there were no significant differences in either scatter or direction among groups. However,...
Show moreHatchling sea turtles emerge at night from underground nests, crawl to the ocean, and swim out to sea. In this study, I determined how offshore orientation and shallow-water predation rates varied under natural (sand bottom and patch reef) and modified (submerged breakwater and open-beach hatchery) ecological circumstances. Hatchling offshore orientation in the sea was normal under all conditions; there were no significant differences in either scatter or direction among groups. However, predators (tarpon, snapper, barracuda, jacks, and grouper) took more hatchlings as they swam over submerged reefs, and after they entered the water in front of hatcheries. Predators were concentrated at both of these sites probably because prey (small fishes and invertebrates at patch reefs and turtles entering the water where nests were concentrated in hatcheries) occur in greater abundance.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15282
- Subject Headings
- Loggerhead turtle, Sea turtles--Orientation, Animal navigation
- Format
- Document (PDF)
- Title
- Which Way is It? Spatial Navigation and the Genetics of Head Direction Cells.
- Creator
- Lora, Joan C., Stackman, Robert W., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
- Abstract/Description
-
From locating a secure home, foraging for food, running away from predators, spatial navigation is an integral part of everyday life. Multiple brain regions work together to form a three-dimensional representation of our environment; specifically, place cells, grid cells, border cells & head direction cells are thought to interact and influence one another to form this cognitive map. Head direction (HD) cells fire as the animal moves through space, according to directional orientation of the...
Show moreFrom locating a secure home, foraging for food, running away from predators, spatial navigation is an integral part of everyday life. Multiple brain regions work together to form a three-dimensional representation of our environment; specifically, place cells, grid cells, border cells & head direction cells are thought to interact and influence one another to form this cognitive map. Head direction (HD) cells fire as the animal moves through space, according to directional orientation of the animal’s head with respect to the laboratory reference frame, and are therefore considered to represent the directional sense. Interestingly, inactivation of head direction cell-containing brain regions has mixed consequences on spatial behavior. Current methods of identifying HD cells are limited to in vivo electrophysiological recordings in a dry-land environment. We first developed a dry-land version of the MWM in order to carry out behavioral-recording paired studies. Additionally, to learn about HD cells function we quantified expression of neuronal activation marker (c-Fos), and L-amino acid transporter 4 (Lat4) in neurons found within the HD cell dense anterodorsal thalamic nucleus (ADN) in mice after exploratory behavior in an open field, or forward unidirectional movement on a treadmill. We hypothesize that the degree to which ADN neurons are activated during exploratory behavior is influenced by the range of heading directions sampled. Additionally, we hypothesize that c-Fos and Lat4 are colocalized within ADN neurons following varying amounts of head direction exposure. Results indicate that following free locomotion of mice in an open field arena, which permitted access to 360° of heading, a greater number of ADN neurons express c-Fos protein compared to those exposed to a limited range of head directions during locomotion in a treadmill. These findings suggest that the degree of ADN neuronal activation was dependent upon the range of head directions sampled. We observed a high degree of colocalization of c-Fos and Lat4 within ADN suggesting that Lat4 may be a useful tool to manipulate neuronal activity of HD cells. Identifying genetic markers specific to ADN helps provide an essential understanding of the spatial navigation system, and supports development of therapies for cognitive disorders affecting navigation.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004931, http://purl.flvc.org/fau/fd/FA00004931
- Subject Headings
- Psychobiology., Spatial behavior in animals., Mice as laboratory animals., Navigation--Psychological aspects., Computational intelligence.
- Format
- Document (PDF)
- Title
- Can hatchlings exposed to beach lighting recover, and orient normally offshore?.
- Creator
- Lorne, Jacquelyn Kay, Florida Atlantic University, Salmon, Michael
- Abstract/Description
-
Artificial lighting disrupts sea turtle hatchling orientation from the nest to the sea. I studied how a light-induced landward crawl affects the ability of hatchlings to later crawl to the sea, and swim offshore from a dark beach. A brief (2 min) landward crawl had no effect on orientation, as long as waves (used as an orientation cue while swimming) were present. In the absence of waves (a flat calm sea), landward-crawling hatchlings failed to swim offshore while those crawling seaward were...
Show moreArtificial lighting disrupts sea turtle hatchling orientation from the nest to the sea. I studied how a light-induced landward crawl affects the ability of hatchlings to later crawl to the sea, and swim offshore from a dark beach. A brief (2 min) landward crawl had no effect on orientation, as long as waves (used as an orientation cue while swimming) were present. In the absence of waves (a flat calm sea), landward-crawling hatchlings failed to swim offshore while those crawling seaward were well oriented. A longer (2 h) landward crawl impaired the ability of hatchlings to crawl to the sea. These results demonstrate that previous exposure to artificial lighting compromises subsequent orientation, both on land and in the sea. On the basis of my results, I suggest several changes to current management practices, currently used when releasing misoriented turtles in the wild.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13400
- Subject Headings
- Sea turtles--Atlantic Coast (U S )--Geographical distribution, Light pollution, Animal orientation, Loggerhead turtle--Orientation, Animal navigation
- Format
- Document (PDF)
- Title
- Do embedded roadway lights protect sea turtles?.
- Creator
- Bertolotti, Lesley L., Florida Atlantic University, Salmon, Michael
- Abstract/Description
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Pole-mounted street lighting on coastal roadways is often visible in adjacent areas. At roadways near sea turtle nesting beaches, these lights can disrupt the nocturnal orientation of hatchlings as they crawl from the nest to the sea. Our objective was to determine if an alternative lighting system (light-emitting diodes, embedded in the roadway pavement) prevented orientation disruption of loggerhead hatchlings. Hatchlings at the beach oriented normally when the embedded lights were on, or...
Show morePole-mounted street lighting on coastal roadways is often visible in adjacent areas. At roadways near sea turtle nesting beaches, these lights can disrupt the nocturnal orientation of hatchlings as they crawl from the nest to the sea. Our objective was to determine if an alternative lighting system (light-emitting diodes, embedded in the roadway pavement) prevented orientation disruption of loggerhead hatchlings. Hatchlings at the beach oriented normally when the embedded lights were on, or when all lighting was switched off. However, turtles showed poor orientation when exposed to pole-mounted street lighting. Light measurements revealed that street lighting was present at the beach, whereas embedded lighting was absent. I conclude that embedded lighting systems restrict light scatter, leaving adjacent habitats dark, and therefore protect the turtles from artificial lighting allowing for normal seafinding.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13203
- Subject Headings
- Loggerhead turtle, Animal navigation, Animal orientation, Sea turtles--Orientation, Exterior lighting--Environmental aspects, Light pollution
- Format
- Document (PDF)
- Title
- Visual wavelength discrimination by the loggerhead turtle, Caretta caretta.
- Creator
- Young, Morgan, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Little is known about the visual capabilities of marine turtles. The ability to discriminate between colors has not been adequately demonstrated on the basis of behavioral criteria. I used a three-part methodology to determine if color discrimination occurred. FIrst, I exposed naèive, light-adapted hatchlings to either a blue, green or yellow light. I manipulated light intensity to obtain a behavioral phototaxis threshold to each color, which provided a range of intensities we knew turtles...
Show moreLittle is known about the visual capabilities of marine turtles. The ability to discriminate between colors has not been adequately demonstrated on the basis of behavioral criteria. I used a three-part methodology to determine if color discrimination occurred. FIrst, I exposed naèive, light-adapted hatchlings to either a blue, green or yellow light. I manipulated light intensity to obtain a behavioral phototaxis threshold to each color, which provided a range of intensities we knew turtles could detect. Second, I used food to train older turtles to swim toward one light color, and then to discriminate between the rewarded light and another light color ; lights were presented at intensities equally above the phototaxis threshold. Lastly, I varied light intensity so that brightness could not be used as a discrimination cue. Six turtles completed this task and showed a clear ability to select a rewarded over a non-rewarded color, regardless of stimulus intensity. Turtles most rapidly learned to associate shorter wavelengths (blue) with food. My results clearly show loggerheads have color vision. Further investigation is required to determine how marine turtles exploit this capability.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3352879
- Subject Headings
- Color vision, Visual discrimination, VIsual perception, Selectivity (Psychology), Photoreceptors, Loggerhead turtle, Orientation, Sea turtles, Orientation, Animal navigation
- Format
- Document (PDF)
- Title
- Nest-to-surf mortality of loggerhead (Caretta caretta) sea turtle hatchlings on Florida’s east coast in 2016.
- Creator
- Erb, Victoria, Wyneken, Jeanette, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Worldwide, sea turtles are especially vulnerable immediately after emerging from nests. Many monitoring programs measure hatchling production from nest inventories. These inventories rarely account for mortality occurring post-emergence, leaving an incomplete estimate of hatchling production. This study addresses the nest-to-surf data gap for Florida’s east coast nesting assemblages of loggerhead sea turtles (Caretta caretta). Five locations were surveyed during the 2016 nesting season by...
Show moreWorldwide, sea turtles are especially vulnerable immediately after emerging from nests. Many monitoring programs measure hatchling production from nest inventories. These inventories rarely account for mortality occurring post-emergence, leaving an incomplete estimate of hatchling production. This study addresses the nest-to-surf data gap for Florida’s east coast nesting assemblages of loggerhead sea turtles (Caretta caretta). Five locations were surveyed during the 2016 nesting season by using infrared time-lapse imagery, night vision optics, and track maps. Over all beaches, 7.6% of the observed hatchlings did not survive to reach the water. Mortality sources varied by location. Observed predators included: foxes, bobcats, yellow-crowned night herons, ghost crabs, and gulls. Hatchling disorientation and misorientation occurred more frequently in urban areas than natural areas. Factors including number of hatchlings emerging, nest-to-surf distance, and urbanization may help managers estimate nest-to-surf mortality. This study will improve life history models that serve as foundations of conservation management.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004934, http://purl.flvc.org/fau/fd/FA00004934
- Subject Headings
- Sea turtles--Mortality--Florida., Loggerhead turtle--Mortality., Predation (Biology), Sea turtles--Orientation., Animal navigation., Fire ants--Venom--Physiological effect.
- Format
- Document (PDF)