>I don't know about the tortoises, but there are some species that do
>not age, most notably some fishes and lobsters. They do not age, and
>just grow slowly larger until an accident or lack of food does them
>in. I don't have Leonard Hayflick's _How and Why We Age_ here, but he
>discuss this subject.
Yes, I've read these anecdotal accounts about the lack of aging in some
fish, sharks, and lobsters - but I cannot find any real scientific
articles on the subject. This is a pity, because if this phenomenon is
real, then it should be looked at very closely. Maybe aging is linked to
terminal cellular differentiation, which in turn limits body size. Having
a small body is an evolutionary advantage in some ecological niches.
Judging from the size of some dinosaurs, maybe the unlimited body
size/immortal phenomenon existed long ago, and some prehistoric animals
lived hundreds of years! Some huge trees even live thousands of years!
Tony B. Csoka