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Ortiz Lab - University of California, Santa Cruz
Physiology of Northern Elephant Seals
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Philosophy of the Lab by C. Leo Ortiz (Professor of Biology)
Marine mammals have fascinated man throughout history, but it is only recently that science has begun to examine the evolutionary, behavioral, and physiological details of their life histories. Each winter, a large population of northern elephant seals (Mirounga angustirostris) breeds at Año Nuevo near Santa Cruz. This event provides a unique opportunity for studying these animals from a broad biological perspective. For over two decades, our research has focused on the physiology of the northern elephant seal during its annual return to land to conduct the terrestrially obligate functions of reproducing and molting. During these periods on land, which may exceed three months per year, animals fast entirely and have no access to fresh water. A major goal of our research is to understand the physiological mechanisms that underlie these remarkable fasts as they relate to the life history strategies of these seals. This fasting period inherently provides a unique opportunity to study mammalian physiological homeostasis under extreme but natural conditions. Early studies included measuring water and energy metabolism during long-term starvation, amino acid conservation, fat metabolism, changes in milk composition during lactation, and the development of nursing and weaned pups. The success of these earlier studies encouraged us to expand our research, which now includes looking for other ways these animals conserve water, how they hormonally regulate metabolism and reproduction, and how they handle nitrogen and other waste metabolites. We are firmly convinced that the multidisciplinary approach we have taken in studying the physiology of the northern elephant seal will provide a more detailed understanding not only of other pinnipeds, but of marine mammals in general.
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Ortiz, Rudy M. Ph.D. candidate. I am interested in the effects of prolonged fasting by elephant seal pups on renal function and hormonal regulation of metabolism during this period. The majority of my previous studies have focused on the effects of altered environments on water and electrolyte homeostasis and metabolism.
Ambat, Eric. M.S. student. Presently, I am conducting research on the behavior of condors in Argentina.
Undergraduates: |
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Giulia Gurun, Beate Litz, and Alex Ramirez
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Kohin, Suzanne. June 1998. Respiratory physiology of northern elephant seal pups: adaptations for hypoxia, hyercapnia and hypometabolism.
Kirby, Vicky. December 1992. The regulation of fuel homeostasis in young northern elephant seals.
Buckendahl, Patricia Buckendahl. June 1992. Ontogeny of morphological & biochemical characteristics of the ulna northern elephant seals.
Aurioles-Gamboa, David. December 1988. Behavior ecology of the California sea lions in the Gulf of California.
Condit, Richard. June 1984. Feeding biology of the northern elephant seal.
Pernia, Sherman. June 1984. Protein turnover & nitrogen metabolism during long term fasting in northern elephant seal pups.
Keith, Edward. June 1984. Glucose metabolism in fasting elepant seal pups.
Hedgecock, Edward. September 1977. GABA metabolism in Caenorhabditis elegans.
Miller, Jeffery J. December 1976. Aplysia giant neuron: An electrophysiological comparison of the soma and the axon.
Ortiz, C.L., D. Costa, and B.J. Le Boeuf. 1978. Water and energy flux in elephant seal pups fasting under natural conditions. Physiological Zoology 51(2):166-178.
Pernia, S.D., A. Hill, and C.L. Ortiz. 1980. Urea turnover during prolonged fasting in the northern elephant seal. Comparative Biochemistry and Physiology 65B: 731-734.
Costa, D.P. and C.L. Ortiz. 1982. Blood chemistry homeostasis during prolonged fasting in the northern elephant seal. American Journal of Physiology 242:R591-R595.
Ortiz, C.L., B.J. Le Boeuf, and D.P. Costa. 1984. Milk intake of elephant seal pups: an index of parental investment. The American Naturalist 124(3): 416- 422
Costa, D.P., B.J. Le Boeuf, A.C. Huntley, and C.L. Ortiz. 1986. The energetics of lactation in the northern elephant seal, Mirounga angustirostris. Journal of Zoology, London 209: 21-33.
Condit, R.S. and C.L. Ortiz. 1987. The physiological transition from fasting to feeding in weaned elephant seal pups. Marine Mammal Science 3(3): 207-219.
Ortiz, C.L. 1988. Measurement of protein metabolism in naturally fasting phocids. Pages 29-42, In: Approaches to Marine Mammal Energetics. A.C. Huntley, D.P. Costa, G.A.J. Worthy and M.A. Castellini (eds). Allen Press, Lawrence, KS.
Keith, E.O., and C.L. Ortiz. 1989. Glucose kinetics in neonatal elephant seals during postweaning aphagia. Marine Mammal Science 5(2): 99-115.
Pernia, S.D., D.P. Costa, and C.L. Ortiz. 1989. Glomerular filtration rate in weaned elephant seal pups during natural, long term fasts. Canadian Journal of Zoology 67: 1752-1756.
Bryden, M.M., P. Buckendahl, J. Sanders, C.L. Ortiz, and D.J. Kennaway. 1994. Plasma melatonin concentration in neonatal northern elephant seals, Mirounga angustirostris. Comparative Biochemistry and Physiology 109A: 895-904.
Patterson-Buckendahl, P., S.H. Adams, R. Morales, W.S.S. Jee, C. Cann, and C.L. Ortiz. 1994. Skeletal development in newborn and weanling northern elephant seals. American Journal of Physiology 267: R726-R734.
Ortiz, R.M., S.H. Adams, D.P. Costa, and C.L. Ortiz. 1996. Plasma vasopressin levels and water conservation in fasting, postweaned northern elephant seal pups (Mirounga angustirostris). Marine Mammal Science 12(1): 99-106.
Ortiz, R.M., C.E. Wade and C.L. Ortiz. 2000. Prolonged fasting increases the response of the renin-angiotensin-aldosterone system, but not vasopressin levels, in postweaned northern elephant seal pups. General and Comparative Endocrinology 119: 217-223.
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