Date of Award

2020

Document Type

Thesis

Degree Name

Master of Science

College

College of Arts and Sciences

Program

Biology, MS

First Advisor

Daniel Gonzalez-Socoloske

Second Advisor

Benjamin Navia

Third Advisor

Robert E. Zdor

Abstract

Manatees are herbivorous aquatic mammals found in the coastal and inland waters of the Atlantic Ocean. All three manatee species are currently listed as vulnerable on the IUCN red list and there still remains much unknown about their ecology. It is currently unknown what sensory modalities manatees use to locate their food in the wild. A literature review of the Paenungulata clade (sirenians, proboscideans, and hyracoideans) was conducted in order to compare and contrast what is known about the sensory modalities of the clade, to better understand the sensory modalities of manatees, particularly the ones they use to locate their food. Manatees have a higher frequency range for hearing than elephants, who have the best low-frequency hearing range known to mammals; hearing range of hyrax is unknown. All members of Paenungulata have vibrissae assisting in tactile abilities and potentially compensate for other senses such as hearing or vision. The ability to smell in manatees and hyrax is unknown, but elephants have been found to have an excellent sense of smell. Manatees, elephants, and hyrax have dichromatic vision. A preliminary experiment was designed to test manatee feeding modalities in the wild.

The objectives of this study were to determine if the proposed methodology, modified for an aquatic environment from Renda & Roux (2017), was capable of testing manatee sensory use by limiting the sensory cues provided. Sensory modalities used in locating food were tested in two ways: when they know where the food is located, within a short distance, and when the food is placed randomly throughout their habitat, at long distances.

In this study, we were able to show that the experimental design works, and provide preliminary data. In the short distance dichotomous choice trials, the percent of correct choices were 67% for the chemoreception + vision, 60% for chemoreception only, and 60% for vision only, with 50% being the rate of chance. For long distance experiments, the mean minimum time in hours it took manatees to consume the food placed randomly along their habitat of San San-Pond Sak River, Panama was 12.0 hours for chemoreception + vision, more than 22 hours for chemoreception only, and 6.89 hours for the control (no box). Due to the small sample size, no definitive conclusion could be made as to which sensory modality manatees use to find food, but our results support the idea that manatees use multiple modalities, chemoreception + vision, to locate food. Additional trials are needed in order to perform statistical analysis on the data.

Subject Area

Manatees--Food; West Indian manatee--Food

DOI

https://dx.doi.org/10.32597/theses/183/

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