Advertisement

Biology Bulletin

, Volume 44, Issue 7, pp 820–825 | Cite as

Age-Related Changes in Functional Teeth in the Pacific Walrus (Odobenus rosmarus divergens)

  • N. V. Kryukova
Article
  • 12 Downloads

Abstract

We examined functional teeth (except for upper canine teeth) of Pacific walruses that died or were harvested on the coast of the Chukchi Peninsula in 2005, 2007–2008, and 2010–2011. The dynamics of deposition of annual cement layers was investigated. The rate of cement deposition on the walls of tooth roots decreased significantly with age. The rate of its deposition on the lingual side of the upper teeth was much higher than that on their buccal side, but no such differences were observed on the lower teeth. The same cement layer was deposited unevenly in different parts of teeth (on its different sides and levels) with a general tendency of increasing in the width of the layer from the top to the lower parts of teeth. As a result of local widening of some cement layers with age, the tooth surface became rough, and knolls and rollers appeared there. As the age increased, external changes in teeth occurred: they became larger, more rounded, and heavier. We described a method for the preliminary determination of the relative age of walruses based on the ratio between the width of cement and dentin on the attrition surface of lower teeth (without cutting).

Keywords

age-related changes tooth size annual layer cement age determination pinnipeds walrus Odobenus rosmarus 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Cobb, W.M., The dentition of the walrus (Odobenus obesus), Proc. Zool. Soc. London, 1933, vol. 103, no. 3, pp. 645–668.CrossRefGoogle Scholar
  2. Fay, F.H., Ecology and biology of the Pacific walrus, Odobenus rosmarus divergens Illiger, North American Fauna, 1982.Google Scholar
  3. Fay, F.H. and Kelly, B.P., Development of a Method for Monitoring the Productivity, Survivorship, and Recruitment of the Pacific Walrus Population, Final Report, OCSEAP Study MMS 89–0012, Anchorage, AK: Minerals Management Service, 1989.Google Scholar
  4. Grachev, A.I., Summer distribution of the Pacific walrus in the Gulf of Anadyr, in Nauchno-issledovatel’skie raboty po morskim mlekopitayushchim severnoi chasti Tikhogo okeana v 1986–1987 gg. (North Pacific Marine Mammal Research, 1986–1987), Moscow, 1988, pp. 118–123.Google Scholar
  5. Klevezal, G.A., Registriruyushchie struktury mlekopitayushchikh v zoologicheskikh issledovaniyakh (Recording Structures of Mammals in Zoological Research), Moscow: Nauka, 1988.Google Scholar
  6. Krylov, V.I., Age determination, growth rate, and age population structure of the Pacific walrus, in Morskie mlekopitayushchie (Marine Mammals), Moscow: Nauka, 1965, pp. 201–211.Google Scholar
  7. Kryukova, N.V., Dentition in Pacific walrus (Odobenus rosmarus divergens) calves of the year, Biol. Bull. (Moscow), 2012, vol. 39, no. 7, pp. 618–626.CrossRefGoogle Scholar
  8. Kryukova, N.V., The method of age determination of the Pacific walrus (Odobenus rosmarus divergens) using the layered structure of functional teeth, Biol. Bull. (Moscow), 2014, vol. 41, no. 8, pp. 681–689.CrossRefGoogle Scholar
  9. Mansfield, A.W., The Biology of the Atlantic walrus, Odobenus rosmarus rosmarus (Linnaeus) in the Eastern Canadian Arctic, Fisheries Research Board Canada Manuscript Report Series (Biology) 1958, no. 653.Google Scholar
  10. Stewart, R.E.A. and Stewart, B.E., Comparison of between-tooth age estimates of Atlantic walrus (Odobenus rosmarus rosmarus), Marine Mammals Sci., 2005, vol. 21, no. 2, pp. 346–354.CrossRefGoogle Scholar

Copyright information

© Pleiades Publishing, Inc. 2017

Authors and Affiliations

  1. 1.Russian Federal Research Institute of Fisheries and OceanographyMoscowRussia

Personalised recommendations