Introduction
The universe comprises of amazing creatures that rely on the natural habitats for survival. Manatees are aquatic mammals that the only surface in every three to four minutes to breathe. The Amazonian Manatee is considered the smallest of all the existing Manatee species regarding their weight and body size that approximates to 450kgs and three meters in length. Also called the Trichechus inunguis or Sirenia due to their origin, the Amazonian Manatees live in the fresh waters of Amazon River, its swamps, wetlands, and tributaries. The mammals are also found in the blackwater lakes, lagoons and oxbows that are connected to the bigger rivers whose temperatures range between 22ᵒC to 30ᵒC (Gallivan, Best, and Kanwisher, 1983).
According to Douglas Adams and Mark Carwardine (2013), the Amazon Manatees are endangered species since man is the primary predator in need of its meat and oil. On the other hand, the practice of environmental conservation through clearing the marine environment by destroying water hyacinth, water lilies, aquatic grass and other submerging vegetation that make up their main diet contribute to the death of Amazon Manatees through starvation. For this very reason, the authors of the ‘Last Chance To See,’ are dedicated to ways in which environmental conservation can be focused on protecting both animal and plant species that are endangered like the Amazonian Manatee.
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Just like other creatures, the Amazonian Manatees have specified feeding habits that enable them to adapt to their aquatic habitat. They are 100% herbivorous and therefore feed on the available aquatic vegetation like the water grasses, lilies, hyacinth and water lettuce among other vegetation as we have observed earlier. Despite their preferences, their body structure, environment, and climate dictate their feeding character and diet. For instance, compared to their body size the Amazonian Manatees have smaller heads with a broad muzzle that gives them ease to feed on the aquatic vegetation. According to Gallivan and Best (1980) , the vegetation in which Manatees feed on are corrosive, and therefore they contribute to the crashing and breaking of their teeth. To adapt to these impact, throughout their lifetime, their molars continually grow to replace the worn out teeth.
On the other hand, these animals feed mostly during the wet season primarily because of the variety and plenty of vegetation. At the time of these wet seasons, the Manatees feed on a daily basis and in most cases take in an amount of food that is close to eight percent of their weight (Domning, 1982). Therefore in case, an Amazon Manatee weighs 450kg, the amount of vegetation in which the animal will consume in a day will amount to 36kgs. The food is directly ingested into the system after digestion because the animals are not ruminant. Part of the food taken is used up to help in the running of the animal’s system, and some of them are stored as fat in its reservoirs to be used during the fasting season that is mostly in the dry seasons when food is scarce or unavailable. The Amazon dry season begins from September to March, and at these times the Manatees swim back to the main rivers.
About the research done and compiled by Ioni G. Corales and Elton P. Corales (2002), the residue found in the digestive tracts and stool of the Amazonian Manatee indicated that the animals fed mostly on emergent vegetation. A bigger percentage of the plants that were found in the animal’s tract included samples of the Echinochloa Polystichum and Paspalum repens. The Echinochloa Polystichum have planted samples that were observed to be in plenty in the small and large intestines of the Manatees during the high water seasons while the Paspalum repens were mostly found during the lower water seasons. Hence, the samples of feeds that were identified in the animals differed with the climatic changes that influenced the seasons and availability of certain vegetation.
Further research was conducted to determine the most preferred food of the Amazonian Manatee through holding them captive and monitoring their feeding habits. Despite the provision of eleven species of aquatic macrophytes on a daily basis, the tamed Manatees were mostly interested on the emergent vegetation. Among them included the Oryza grandiglumis and paspalum repense grasses. On the other hand, the animals preferred newer plants to older ones hence the age of the vegetation was a considered element to the diet of the Manatee animals. As observed earlier, most aquatic plants are corrosive, hence the older it is, the more corrosive and vice versa, explaining why the animals preferred younger plants to older ones. Amazonian Manatees were also observed to feed on human food like carrots, cabbages, lettuce and apples among others. While these human foods were at times substitutes, ecologists acknowledge that they lack the nutrients and supplements that Manatees need for their survival. Hence, the human vegetation is not the best nutrients supplement for the Manatee.
Conclusion
Every creature has its unique feeding characteristics that contribute to their adaptive measures. The Manatee in the Amazon has distinct feeding habits that are mostly focused on strict vegetation. It is evident that most of the vegetation in which the Amazonian Manatee feed on are emergent and those who are still younger. It has also been observed that the climate seasons dictate the eating habits of the animals since the seasons determine the availability of vegetation or their scarcity.
References
Adams, D., & Carwardine, M. (2013). Last Chance To See. Random House.
Colares, Ioni G., & Colares, Elton P.. (2002). Food Plants Eaten by Amazonian Manatees (Trichechus inunguis, Mammalia : Sirenia). Brazilian Archives of Biology and Technology , 45 (1), 67-72. https://dx.doi.org/10.1590/S1516-89132002000100011
Domning, D. (1982). Evolution of Manatees: A Speculative History. Journal of Paleontology, 56 (3), 599-619. Retrieved from http://www.jstor.org/stable/1304394
Gallivan, G. and Best, R. (1980). Metabolism and Respiration of the Amazonian Manatee (Trichechus inunguis). Physiological Zoology , 53(3), pp.245-253. https://doi.org/10.1086/physzool.53.3.30155787
Gallivan, G., Best, R. and Kanwisher, J. (1983). Temperature Regulation in the Amazonian Manatee Trichechus inunguis. Physiological Zoology , 56(2), pp.255-262. https://doi.org/10.1086/physzool.56.2.30156057
