Reep, Roger Lyons: SEE ALSO Johnson et al., 1994; O'Shea & Reep, 1990; Loerzel & Reep, 1991; Marshall et al., 1998, 2000, 2003; Marshall, Clark & Reep, 1998; Marshall & Reep, 1995.
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O'Shea, Thomas J.; Reep, Roger Lyons
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1990 |
Encephalization quotients and life-history traits in the Sirenia.
Jour. Mamm. 71(4): 534-543. 2 tabs. 2 figs. Dec. 7, 1990.
–Presents data on brain and body size in Recent sirs., and on growth rates and closure of cranial sutures in wild Florida manatees. Concludes that low encephalization quotients in sirs. are due to low metabolic rate and prolonged postnatal growth, leading to a post-weaning increase in body size that is decoupled from brain growth.
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Loerzel, S.; Reep, Roger Lyons
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1991 |
Rindenkerne: unusual neuron aggregates in manatee cerebral cortex.
Internatl. Assoc. Aquatic Animal Med. Proc. 22: 166-171. 1 tab. 2 figs.
–Describes the morphology and distribution of Rindenkerne in the brain of a Florida manatee, and discusses their possible developmental history and possible association with functions of the vibrissae.
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Johnson, John Irwin; Kirsch, John A. W.; Reep, Roger Lyons; Switzer, Robert C.
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1994 |
Phylogeny through brain traits: more characters for the analysis of mammalian evolution.
Brain Behav. Evol. 43(6): 319-347. 5 tabs. 12 figs.
–Reports and analyzes data on nine brain traits (in addition to 15 previously described) in mammals including T. manatus and D. dugon, and analyzes the cladistic relationships among mammalian orders that these traits imply.
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Marshall, Christopher D.; Reep, Roger Lyons
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1995 |
Manatee cerebral cortex: cytoarchitecture of the caudal region in Trichechus manatus latirostris.
Brain Behav. Evol. 45: 1-18. 11 figs.
–Maps and describes cortical areas in the caudal region, and discusses their possible functional roles.
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Marshall, Christopher D.; Clark, L. A.; Reep, Roger Lyons
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1998 |
The muscular hydrostat of the Florida manatee (Trichechus manatus latirostris): a functional morphological model of perioral bristle use.
Mar. Mamm. Sci. 14(2): 290-303. 3 figs. Mar. 31, 1998.
–Describes the anterior facial muscles in serial section; recognizes a new muscle (M. centralis nasi); shows that these muscles meet the definition of a muscular hydrostat; and hypothesizes a sequence of muscle contractions to explain the observed movements of the snout and bristles while feeding. See also Reep et al. (1998) and Marshall et al. (1998).
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Marshall, Christopher D.; Huth, Glenn D.; Edmonds, Virginia M.; Halin, Deborah L. ("D. M. Halin"); Reep, Roger Lyons
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1998 |
Prehensile use of perioral bristles during feeding and associated behaviors of the Florida manatee (Trichechus manatus latirostris).
Mar. Mamm. Sci. 14(2): 274-289. 4 figs. Mar. 31, 1998.
–Reports observations of captive and wild manatees feeding on 6 species of aquatic plants, attempting to manipulate inanimate objects, and in social interactions. Describes details of both prehensile and tactile lip and vibrissal movements. See also Reep et al. (1998) and Marshall, Clark & Reep (1998).
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Reep, Roger Lyons; Marshall, Christopher D.; Stoll, M. L.; Whitaker, D. M.
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1998 |
Distribution and innervation of facial bristles and hairs in the Florida manatee (Trichechus manatus latirostris).
Mar. Mamm. Sci. 14(2): 257-273. 3 tabs. 8 figs. Mar. 31, 1998.
–Describes 6 distinct fields of perioral bristles, density of hair on the face vs. the body, and, in general, the anatomical basis of bristle use during feeding and tactile exploration. See also Marshall et al. (1998) and Marshall, Clark, & Reep (1998).
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Reep, Roger Lyons; Stoll, M. L.; Marshall, Christopher D.; Homer, B. L.; Samuelson, Don A.
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2001 |
Microanatomy of facial vibrissae in the Florida manatee: the basis for specialized sensory function and oripulation.
Brain Behav. Evol. 58(1): 1-14. 3 tabs. 5 figs.
–Notice: New Scientist, Mar. 23, 2002: 27, 1 fig. Describes the vibrissae and their blood & nerve supply. Confirms that all the facial hairs & bristles are vibrissae (sinus hairs); that these have a distinct combination of attributes in each of the 9 regions of the face; that the perioral bristles have both tactile sensory and prehensile roles (a combination of functions unique to sirs.); and that the facial vibrissae may play a role in hydrodynamic distance reception.
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Reep, Roger Lyons; Marshall, Christopher D.; Stoll, M. L.
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2002 |
Tactile hairs on the postcranial body in Florida manatees: a mammalian lateral line?
Brain Behav. Evol. 59: 141-154. 2 tabs. 9 figs.
–Describes the distribution and microanatomy of the postcranial hair follicles. All hairs are tactile sinus hairs innervated by 20-50 axons; they are arranged and constructed appropriately to detect water currents and possibly the presence of other animals or objects in the environment.
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Marshall, Christopher D.; Maeda, Hiroshi; Iwata, Matsumitsu; Furuta, Masami; Asano, Shiro; Rosas, Fernando César Weber; Reep, Roger Lyons
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2003 |
Orofacial morphology and feeding behaviour of the dugong, Amazonian, West African, and Antillean manatees (Mammalia: Sirenia): functional morphology of the muscular-vibrissal complex.
Jour. Zool. 259(3): 245-260. 2 tabs. 7 figs. Mar. 2003.
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Mann, David A.; Colbert, Debborah E.; Gaspard, Joseph C., III; Casper, Brandon M.; Cook, Mandy L. H.; Reep, Roger Lyons; Bauer, Gordon Bruce
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2005 |
Temporal resolution of the Florida manatee (Trichechus manatus latirostris) auditory system.
Jour. Comp. Physiol. A, Sensory, Neural & Behav. Physiol. 191(10): 903-908.
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Reep, Roger Lyons; Bonde, Robert K.
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2006 |
The Florida manatee: biology and conservation.
Gainesville, Univ. Press of Florida: xviii + 190. Illus.
–Reviews: Lemnuel Aragones, Bull. Mar. Sci. 79(1): 240-241, July 2006; Daniel K. Odell, Florida Scientist 70(3): 303-304, Summer 2007; John E. Reynolds III, Aquatic Mammals 33(2): 251, 2007.
Ed. 2: May 2021, 338 pp.
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Sarko, Diana K.; Reep, Roger Lyons
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2006 |
Somatosensory areas of manatee cerebral cortex: histochemical characterization and functional implications.
Brain Behav. Evol. 69: 20-36. 2 tabs. 7 figs. Publ. online Aug. 14, 2006.
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Johnson, J. I.; Reep, Roger Lyons
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2008 |
Specialized somatosensory systems. In: J. Kaas & E.P. Gardner (eds.), The senses: a comprehensive reference. Vol. 6: Somatosensation.
Elsevier: 331-353.
–Discusses vibrissae in sirs.
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Reep, Roger Lyons; Gaspard, Joseph C., III; Sarko, Diana K.; Rice, Frank L.; Mann, David A.; Bauer, Gordon B.
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2011 |
Manatee vibrissae: evidence for a "lateral line" function.
Annals of the New York Academy of Sciences DOI: 10.1111/j.1749-6632.2011.05992.x. Apr. 2011.
–Aquatic mammals use vibrissae to detect hydrodynamic stimuli over a range from 5 to 150 Hz, similar to the range detected by lateral line systems in fishes and amphibians. Manatees possess ?5,300 vibrissae distributed over the body, innervated by ?209,000 axons. This extensive innervation devoted to vibrissae follicles is reflected in enlarged, elaborate somatosensory regions of the gracile, cuneate, and Bischoff's brain-stem nuclei, ventrobasal thalamus, and presumptive somatosensory cortex. Our preliminary psychophysical testing indicates that in Florida and Antillean manatees the Weber fraction for detection thresholds for grating textures ranges from 0.025 to 0.14. At the lower end of this range, sensitivity is comparable to human index finger thresholds. For hydrodynamic stimuli of 5–150 Hz, detection threshold levels for manatees using facial or postfacial vibrissae were substantially lower than those reported for harbor seals and similar to reports of sensitivity for the lateral line systems of some fish. Our findings suggest that the facial and postfacial vibrissae are used to detect hydrodynamic stimuli, whereas only the facial vibrissae are used for direct contact investigation.
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Sarko, Diana K.; Rice, Frank L.; Reep, Roger Lyons
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2011 |
Mammalian tactile hair: divergence from a limited distribution.
Annals of the New York Academy of Sciences 1225: 90-100. 4 figs. DOI:10.1111/j.1749-6632.2011.05979.x. Apr. 2011.
–ABSTRACT: Mammalian species use tactile hairs to address a variety of perceptual challenges in detecting and responding appropriately to environmental stimuli. With a wide range of functional roles that range from object detection, to fine texture discrimination, to hydrodynamic trail perception, tactile hairs have been adapted for a variety of environmental niches to enhance survival through optimizing detection of somatosensory cues. Because the high level of innervation associated with tactile hairs requires a commensurately high dedication of neural resources, their distribution is restricted to specific regions of the body that encounter stimuli of interest--commonly, the face. However, several species--namely bats, naked mole-rats, hyraxes, manatees, and dugongs--are rare exceptions, with tactile hair distribution that has expanded to cover the entire body. This review examines the behavioral advantages conferred by this unusual trait, the neuroanatomical adaptations that accompany it, and how this pattern might have evolved.
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Bauer, Gordon B.; Gaspard, Joseph C., III; Colbert, Debborah E.; Leach , Jennifer B.; Stamper , Sarah A.; Mann, David; Reep, Roger Lyons
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2012 |
Tactile discrimination of textures by Florida manatees (Trichechus manatus latirostris).
Mar. Mamm. Sci. 28(4): E456-E471. 4 figs. DOI: 10.1111/j.1748-7692.2012.00565.x Oct. 2012 (first published online June 13, 2012).
–ABSTRACT: Two male Florida manatees (Trichechus manatus latirostris) demonstrated sensitive tactile discrimination in a two-alternative forced choice task, using a modified staircase method. Stimuli were acrylic plates with vertical gratings of ridges and grooves. The standard stimulus, present on every trial, had 2 mm gratings and the comparison stimuli had wider gratings. The blindfolded subjects were trained to demonstrate discrimination by pressing the target with wider gratings. Discrimination thresholds (75% correct) for the subjects were 2.05 mm and 2.15 mm, corresponding to Weber fractions of 0.025 and 0.075, respectively. These results indicate thresholds on similar stimuli comparable to humans (index finger tasks) and better than harbor seals, Phoca vitulina, and the closely related Antillean manatee, Trichechus manatus manatus. Memory for the tactile task was quite stable for both subjects, over 2 yr in the case of one of the subjects. Video analysis of responses indicated that bristle-like hairs, perioral bristles, and skin on the oral disk were involved in the discrimination response.
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Gaspard, Joseph C., III; Bauer, Gordon Bruce; Reep, Roger Lyons; Dziuk, Kimberly; Cardwell, Adrienne; Read, LaToshia; Mann, David A.
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2012 |
Audiogram and auditory critical ratios of two Florida manatees (Trichechus manatus latirostris).
Jour. Exper. Biol. 215(9): 1442-1447. DOI:10.1242/jeb.089201. May 2012.
–There is also a comment on this article by Kathryn Knight on p. i of this issue.
ABSTRACT: Manatees inhabit turbid, shallow-water environments and have been shown to have poor visual acuity. Previous studies on hearing have demonstrated that manatees possess good hearing and sound localization abilities. The goals of this research were to determine the hearing abilities of two captive subjects and measure critical ratios to understand the capacity of manatees to detect tonal signals, such as manatee vocalizations, in the presence of noise. This study was also undertaken to better understand individual variability, which has been encountered during behavioral research with manatees. Two Florida manatees (Trichechus manatus latirostris) were tested in a go/no-go paradigm using a modified staircase method, with incorporated 'catch' trials at a 1: 1 ratio, to assess their ability to detect single-frequency tonal stimuli. The behavioral audiograms indicated that the manatees' auditory frequency detection for tonal stimuli ranged from 0.25 to 90.5 kHz, with peak sensitivity extending from 8 to 32 kHz. Critical ratios, thresholds for tone detection in the presence of background masking noise, were determined with one-octave wide noise bands, 7-12 dB (spectrum level) above the thresholds determined for the audiogram under quiet conditions. Manatees appear to have quite low critical ratios, especially at 8 kHz, where the ratio was 18.3 dB for one manatee. This suggests that manatee hearing is sensitive in the presence of background noise and that they may have relatively narrow filters in the tested frequency range.
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Colbert-Luke, Debborah E.; Gaspard, Joseph C., III; Reep, Roger Lyons; Bauer, Gordon B.; Dziuk, Kimberly; Cardwell, Adrienne; Mann, David A.
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2015 |
Eight-choice sound localization by manatees: performance abilities and head related transfer functions.
Jour. Compar. Physiol. A 201(2): 249-259. Feb. 2015.
–ABSTRACT: Two experiments investigated the ability and means by which two male Florida manatees (Trichechus manatus latirostris) may determine the direction of a sound source. An eight-choice discrimination paradigm was used to determine the subjects' sound localization abilities of five signal conditions covering a range of frequencies, durations, and levels. Subjects performed above the 12.5 % chance level for all broadband frequencies and were able to localize sounds over a large level range. Errors were typically located to either side of the signal source location when presented in the front 180° but were more dispersed when presented from locations behind the subject. Front-to-back confusions were few and accuracy was greater when signals originated from the front 180°. Head-related transfer functions were measured to determine if frequencies were filtered by the manatee body to create frequency-specific interaural level differences (ILDs). ILDs were found for all frequencies as a function of source location, although they were largest with frequencies above 18 kHz and when signals originated to either side of the subjects. Larger ILDs were found when the signals originated behind the subjects. A shadowing-effect produced by the body may explain the relatively low occurrence of front-back confusions in the localization study.
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Gaspard, Joseph C., III; Bauer, Gordon B.; Mann, David A.; Boerner, Katharine; Denum, Laura; Frances, Candice; Reep, Roger Lyons
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2017 |
Detection of hydrodynamic stimuli by the postcranial body of Florida manatees (Trichechus manatus latirostris).
Jour. Comp. Physiol. A 203: 111–120. 2 tabs. 4 figs. DOI 10.1007/s00359-016-1142-8. Publ. online Feb. 13, 2017.
–ABSTRACT: Manatees live in shallow, frequently turbid waters. The sensory means by which they navigate in these conditions are unknown. Poor visual acuity, lack of echolocation, and modest chemosensation suggest that other modalities play an important role. Rich innervation of sensory hairs that cover the entire body and enlarged somatosensory areas of the brain suggest that tactile senses are good candidates. Previous tests of detection of underwater vibratory stimuli indicated that they use passive movement of the hairs to detect particle displacements in the vicinity of a micron or less for frequencies from 10 to 150 Hz. In the current study, hydrodynamic stimuli were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz. Go/no-go tests of manatee postcranial mechanoreception of hydrodynamic stimuli indicated excellent sensitivity but about an order of magnitude less than the facial region. When the vibrissae were trimmed, detection thresholds were elevated, suggesting that the vibrissae were an important means by which detection occurred. Manatees were also highly accurate in two-choice directional discrimination: greater than 90% correct at all frequencies tested. We hypothesize that manatees utilize vibrissae as a three-dimensional array to detect and localize low-frequency hydrodynamic stimuli.
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Bibliography and Index of the Sirenia and Desmostylia 