Re: Not dinosaurs but chondrichthyans

[Christopher Taylor <ck.taylor@auckland.ac.nz>]

On 23/4/04 5:05 am, "Tim Williams" <twilliams_alpha@hotmail.com> wrote:

> White sharks (and some other lamniform sharks) display something called
> "regional endothermy", which I've never fully understood.  It does allow
> their body temperature to rise above that of the ambient water temperature.
> 
Lamnid sharks (and tuna) have a retial (network) system of tightly-placed
blood vessels around the viscera. Heat produced by muscle contractions
becomes trapped in the network by opposing blood flows (veins next to
arteries)
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