RE: Big is beautiful - bioenergetics again (long)

[Michael Bruce Habib <mbh3q@cms.mail.virginia.edu>]

On Mon, 17 Sep 2001 09:48:13 +0200 (METDST) Martin Baeker 
<martin@raptor.ifw.ing.tu-bs.de> wrote:

Some very interesting ideas!  I had a quick question 
regarding running in small vs. larger species (clip 
attached below).  What happens if the small animal has 
stride that is relatively huge?  To take an example from 
extant taxa: A modern hare (genus Lepus) can run at 59km/hr 
(roughly).  This is a faster absolute speed than many 
larger species, and a much faster relative speed.  The 
somewhat unique bounding gate gives these animals a huge 
stride length, which explains the speed increase (I 
believe), but they still have a low mass, so I'm curious 
about what happens to the required reaction times for such 
an animal (which might also be say...a very long-legged 
small theropod).

Thanks,
--Mike Habib
mbh3q@virginia.edu
 
> So to run at the same equivalent speed the small animal needs more strides
> per second than the large one and, as the cost of moving one unit of mass
> through one stride is more or less constant, has to have a higher
> metabolic rate.
> 
> However, something I did not find adressed anywhere is the following
> question: Why cannot the smaller animal run at the same speed in relation
> to its own body size. I.e., if the large animal can do 1000 body lengths
> per hour, why cannot the small animal function at the same relative speed?
> It will cover the same area as does the large animal, relative to its
> size, so there is no scaling problem here.  
> 
> So our slow-going mouse will have
> to react VERY quickly whenever the ground is uneven, even if it would like
> to be slow.