The Florida Manatee, Trichechus manatus latirostris, Chemosensory System: Histological Examination of the Gustatory and Olfactory Regions
IAAAM 2009
Meghan L. Bills1; Iskande V. Larkin1; Donald Samuelson1; Julie D. Sheldon2; Kelly M. Evans2
1University of Florida, Aquatic Animal Health Program, College of Veterinary Medicine, Gainesville, FL, USA; 2University of Florida, College of Agricultural and Life Sciences, Gainesville, FL, USA


The utilization of taste and smell in reproduction is well documented in terrestrial mammals and small aquatic vertebrates but has never been fully examined in aquatic mammals.7 The endangered Florida manatee, Trichechus manatus latirostris, is one of many marine mammals suspected of utilizing chemosensation for reproductive purposes,2,5 but nothing conclusive has been demonstrated.1,6 Due to anatomical evidence including olfactory epithelium4 and taste buds3 in addition to behavioral observations of manatees' rubbing, mouthing, and sniffing, it has been hypothesized that the manatee is capable of sensing a female in estrus.2,5

Through gross and histological examination of suspected sites of chemoreception a more thorough analysis of the manatee's anatomical capabilities is possible. To date three males: perinatal, subadult, and adult and two females: subadult and adult have been assessed using gross documentation and histological processing with haematoxylin and eosin staining. The histological examination of the mouth area and nasal passages of the manatee has corroborated the presence of taste buds and olfactory epithelium. In addition gross examination of the internal and external mouth area demonstrates the presence of potential, additional receptor sites including papillae of the soft palate and cheek. The external genitalia of females have secretory areas that may be a source of signal. Through a larger sample size and more in depth histological analysis, any differences in age and sex will be demonstrated and the chemoreceptive areas will be further characterized.


1.  Ceruti M.G., P.V. Fennessey, and S.S. Tjoa. 1985. Chemoreceptively active compounds in secretions, excretions and tissue extracts of marine mammals. Comp Biochem Physiol 82A (3): 505-514.

2.  Hartman D.S. 1979. Ecology and behavior of the manatee (Trichechus manatus) in Florida. In: J. Layne, (ed). Special Publication No. 5: The American Society of Mammalogists; Pp. 118-120.

3.  Levin M.J, and C.J. Pfeiffer. 2002. Gross and microscopic observations on the lingual structure of the Florida manatee, Trichechus manatus latirostris. Anat Histol Embryol 31: 278-285.

4.  Makay-Sim A., D. Duvall, and B.M. Graves. 1985. The West Indian manatee (Trichechus manatus) lacks a vomeronasal organ. Brain Behav Evol 27: 186-194.

5.  Rathbun G.B., and T.J. O'Shea. 1984. The manatee's simple social life: scent marking in an aquatic mammal. In: D. Macdonald (ed). The Encyclopedia of Mammals. New York, NY: Facts on File; Pp. 300-301.

6.  Watkins W.A., and D. Wartzok. 1985. Sensory biophysics of marine mammals. Mar Mam Sci 1(3): 219-260.

7.  Wyatt T.D. 2003. Pheromones and Animal Behaviour: Communication by Smell and Taste. Cambridge: Cambridge University Press.


Speaker Information
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Meghan L. Bills
University of Florida, Aquatic Animal Health Program
College of Veterinary Medicine
Gainesville, FL, USA

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