Foods and feeding habits of wild and captive Sirenia

Abstract

The Sirenia along with the elephants and hyraxes form the Super‐Order Paenungulata. They are the only fully aquatic mammalian herbivores and are represented by three species of manatees (Trichechidae), the dugong and the now extinct, Steller's sea cow (Dugongidae). Sirenians are non‐ruminant herbivores that have specialized hind‐gut fermentation in a large paired caecum at the juncture of the large and small intestines. The stomach is relatively small and is characterized by a unique cardiac gland which contains most of the digestive‐enzyme secreting cells. Little is known of the digestive physiology of sirenians. The metabolic rate of the manatee is very low in comparison to other mammals and may even represent the lowest weight‐specific metabolic rate for any mammal known. Metabolic rates for Dugong have not yet been determined. Foods and feeding habits of these species are reviewed both qualitatively and quantitatively. Manatees consume approximately 896 of their total body weight in aquatic plants daily, whereas the same value for the dugong is about 14%. Digestibilities of aquatic plants vary from 45 to 70% for manatees and a single in vitro measurement for Dugong was 83% for sea‐grass. The chemical composition of various plants consumed by wild and captive sirenians are presented and their value in the nutritional ecoloev of the different species is discussed.

Food Plants Eaten by Amazonian Manatees (Trichechus inunguis, Mammalia : Sirenia)

“…Similar observations were made in dugongs and West Indian manatees (Lipkin, 1975;Wake, 1975;Ledder, 1986). Hartman (1979) and Best (1981) reported that manatees consumed considerable quantities of organisms which were found in large numbers on the roots and leaves of aquatic macrophytes. The presence of sand grains and decomposing vegetable matter encountered in samples during low water was supported by Best (1981), who indicated that when availability of food decreased during this period, they used decomposing material and mud as a food supplement.…”

“…Domning (1981) quoted observations made by local fisherman in the regions of Pará, Maranhão, Amazonas and Amapá (Brazil), who confirmed having seen animals feeding on different species of submerged, floating, and emergent plants. The availability of aquatic and semi-aquatic plants on which the manatee feeds (Best, 1984) varies greatly depending on the levels of the rivers between the low and high water periods of the Amazon basin (Junk, 1970;Colares & Colares, 1987), and is believed that seasonal variation in their diet is due to variation in the availability of these plants (Best, 1981). The main objective of this study was to determine the feeding habits of the Amazonian manatees (T. inunguis) in some rivers and lakes of the central Amazon.…”

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“…Echinochloa polystachya, embora considerada bastante abundante nos rios da Bacia Amazônica (Junk, 1970;Piedade, 1988) aderidos em suas raízes e folhagens (Junk, 1973;Best, 1981). Possivelmente, os peixes-bois, ao alimentarem-se destas plantas com elevados teores de cinzas, provocados por estas incrustações de microorganismos (Boyd, 1968), estejam obtendo em sua dieta uma suplementação de cálcio, cujos teores, para as plantas da Amazônia Central, são extremamente baixos (Howard-Williams & Junk, 1977).…”

Spatial and temporal distribution of manatees (trichechus manatus) reintroduced in the northeastern coast of Brazil

“…BEST (1981) andDEUTSCH et al, (2003) suggest that they are individually very flyable in using different means of fodder in different communities of plants. The highlighted seasonality in some reintroduced manatees´ movements does not find evidences in this study, like a seeking for food or the main factor which causes these displacements, once these motions always made from the Sites of Fidelity with permanent environmental characteristics favorable to the animals´ permanence.…”