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Rudy M Ortiz Lab

West Indian Manatees

West Indian Manatee

Research for my Master of Science thesis conducted at Texas A&M University focused on water flux and osmoregulation in West Indian manatees. Previous studies had suggested that West Indian manatees could actively drink salt water (mariposia) based on urine data, their renal anatomy, and their occurrence in marine habitats for extended periods. Because West Indian manatees inhabit both fresh water and marine environments, they provided an ideal model to address the questions of water balance and osmoregulation in marine mammals.

Through a series of manipulations with fresh and salt water, we were able to demonstrate that manatees do not actively drink salt water, and that incidental ingestion of salt water during feeding elicited typical mammalian endocrine responses resulting in excretion of the excess salt load. However, captive animals consumed large amounts of fresh water (photo above), which could make them susceptible to hyponatremia if access to a source of salt is not provided.

West Indian Manatee
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Ortiz, R.M., G.A.J. Worthy and D.S. MacKenzie. 1998. Osmoregulation in free ranging and captive West Indian manatees (Trichechus manatus). (pdf 720 Kb) Physiological Zoology 71(4):449-457.

Ortiz, R.M., G.A.J. Worthy and F.M. Byers. 1999. Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in salt and fresh water.( pdf 38 Kb) The Journal of Experimental Biology 202(1):33-38.