Extant members of Paenungulata (sirenians, proboscideans, and hyracoideans) form a monophyletic clade which originated in Africa. While paenungulates are all herbivorous, they differ greatly in size, life history, and habitat. Therefore, we would expect both phylogenetically related similarities and ecologically driven differences in their use and specializations of sensory systems, especially in adaptations in sirenians related to their fully aquatic habitat. Here we review what is known about the sensory modalities of this clade in an attempt to better elucidate their sensory adaptations. Manatees have a higher frequency range for hearing than elephants, who have the best low‐frequency hearing range known to mammals, while the hearing range of hyraxes is unknown. All paenungulates have vibrissae assisting in tactile abilities such as feeding and navigating the environment and share relatively small eyes and dichromatic vision. Taste buds are present in varying quantities in all three orders. While the olfactory abilities of manatees and hyraxes are unknown, elephants have an excellent sense of smell which is reflected by having the relatively largest cranial nerve related to olfaction among the three lineages. Manatees have the relatively largest trigeminal nerve—the nerve responsible for, among other things, mystacial vibrissae—while hyraxes have the relatively largest optic nerve (and therefore, presumably, the best vision) among the Paenungulata. All three orders have diverged significantly; however, they still retain some anatomical and physiological adaptations in common with regard to sensory abilities.

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.