MadSci Network: Zoology

Re: At what age would a male tortoise stop reproducing?

Date: Mon Jan 16 11:58:27 2006
Posted By: dave armstrong, Faculty, Biology, Cricklade college
Area of science: Zoology
ID: 1136123633.Zo

    This question is one which rarely supercedes the perenial query about age 
of certain tortoises. The Kenyan tortoise here may be a giant Aldabran 
tortoise, of which there are many in various zoos. This means we can age 
and check reproduction of males. However the prime directive for many 
zoologists is the production and care of the eggs. Females are therefore 
studied, along with their fertility. Poor old males are stimulated electrically 
and whether they would be able to produce sperm in the wild or not, active 
sperm apparently appear from these middle-aged individuals around 130.   
  This brings us back to the reason for great age in certain animals. The big 
answer is that tortoises metabolise very slowly and can survive without 
oxygen for long periods. Each species must differ, especially if we compare 
the carnivorous aquatic examples with the traditional vegetarian land 
  In the end the only conclusion can be that  a large enough tortoise cares 
little about age. "Lonely George", on the Galapagos island of Pinta survives 
without possibly ever having met a female in his maturity. The search for a 
possible mate from his own island or another island with almost matching 
DNA is fascinating. What seems little in doubt is whether his actual age is 
important in determining his virility. His sperm could be extracted by fair 
means or foul, if a mate turns up.

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