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Barboza, Meghan L. B.; Larkin, Iskande V.
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2020 |
Gross and microscopic anatomy of the nasal cavity, including olfactory epithelium, of the Florida manatee Trichechus manatus latirostris.
Aquat. Mamms. 46(3): 274-284. https://doi.org/10.1578/AM.46.3.2020.274 May 11, 2020.
–ABSTRACT: As a fully aquatic mammal, the Florida manatee (Trichechus manatus latirostris) spends a limited amount of time at the water's surface. However, as a mammal that breathes air, they do need to filter, warm, and humidify that air, and anecdotal evidence indicates manatees have a sense of smell. This study characterized the nasal turbinate system, including identification of the olfactory epithelium, and compared it to other mammals using a combination of gross and micro-anatomic examination. Major turbinates were present, including nasal, maxillary, and ethmoturbinates, but with minimal convolution. The respiratory epithelium was found throughout much of the nasal cavity and covered maxillary and nasal turbinates, as well as the septum. Mucus-producing cells and cavernous veins were extensive. The olfactory epithelium was found in the dorsocaudal ethmoturbinates. As a herbivore that feeds predominantly underwater, the manatee likely relies on taste and touch for assessing food and, therefore, does not need to use smell in the same way as other marine mammals such as mysticetes (Bouchard et al., 2019) and pinnipeds (Kowalewsky et al., 2006). However, there are still substantial numbers of olfactory cells, especially considering the decreased amount of exposure time to odorants when breathing at the surface. Therefore, the question remains of why manatees have maintained their ability to smell while other fully aquatic species such as odontocetes have not. Future research should focus on a combination of behavioral and molecular techniques to fully understand the olfactory capabilities of the Florida manatee.
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Barboza, Meghan L. B.; Larkin, Iskande V.
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2020 |
Functional morphology of the taste buds of Florida manatee, Trichechus manatus latirostris.
Mar. Mamm. Sci. 36(3): 939-952. https://doi.org/10.1111/mms.12692 July 2020 (publ. online Apr. 21, 2020).
–ABSTRACT: The Florida manatee, Trichechus manatus latirostris, is a fully aquatic, threatened marine mammal for which increased understanding of their physiology, reproduction, and nutrition supports management decisions. Manatees may use taste to distinguish saltwater gradients, toxin detection, food assessment, and social interactions. This study sought to locate and characterize manatee taste buds comparing location, structure, number, and size to other species.
Entire heads from manatees (6 males, 4 females) of various ages were obtained. The muzzle, tissue surrounding the nares, oral cavity, and epiglottis were examined grossly for pits and papillae. Tissues were examined using light and transmission electron microscopy. Within the predominant taste bud location, the tongue root, taste bud number was estimated using samples from four animals.
The average number of taste buds within the tongue root was 11,534 (range 2,711–23,237) with sparse taste buds located on the soft palate and epiglottis. The location along the lateral surface of the tongue root and bordered by grooves, through which tastants could be easily transported, has functional significance. Large numbers of taste buds within the tongue root suggest that taste is an important component of manatee sensory systems and behavioral research would clarify this.
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Bibliography and Index of the Sirenia and Desmostylia 