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In article <v01540b06aeb53b50871e@[]>, Jeff Poling
<jpoling@dinosauria.com> wrote

>   There is at least one ectothermic mammal, the naked mole rat, and two
>scaled mammals, the armadillo and rat (my ref. was published in 1987, so
>this may be out of date.  As of 1987, though, the scales were considered
>"reptilian", not conglomerated hairs like the scales of pangolins).
Is the naked mole rat  (Heterocephalus glaber) truely an ectotherm ? It
certainly allows its body temperature to drop to the ambient temperature
(tested in the laboratory for a range of 12 to 37 C) but it rarely encounters
a temperature outside the range of 28 to 32 C in its natural habitat. It does
not come out of the burrows to get the energy from the sun (usual
behaviour of an ectotherm). There is no other source of energy in the
burrows where it lives permanently other than the energy produced by the
members of the colony. The term poikilotherm has been used for this
animal (Cossins A R, Cold facts and naked truth, Nature 1991; 353: 699).
Has it been shown that it acquires a significant amount of energy from the
environment ? Unless it does so (i.e., if it generates most of its energy
internally, irrespective of its body temperature) it is not a true ectotherm.

Gautam Majumdar         gautam@majumdar.demon.co.uk