SOMA VS STEM CELLS. “In mammals with a limited growth phase, telomerase activity in somatic tissues is restricted to stem cell derivatives with high proliferation potential. But other animals, like some fish, grow throughout their life with little senescence. All somatic cells require a high proliferation capacity and telomerase should be active in all cells, irrespective of fish age”
http://onlinelibrary.wiley.com/doi/10.1016/S0014-5793(98)01020-5/full