Actually hedgehog spines are slightly curved so that they will always go into
Euler buckling. Because if they weren't curved they'd act like cpolumns, since
their aspect ratio is about 20 which is about the upper limit for a column. So
they are as stiff as they can be in terms of resisiting Euler buckling, but are
totally designed to buckle in an Euler mode.
Antlers are totally different. Whereas hedgehog spines depend on structure and
shape for their energy absorption, antlers rely almost solely on their material
properties, assuming they are wet (when dry they have the same stiffness and
toughness as cow leg bone, which tells you that the trick is to do with the way
the structure works - in this case it appears to be decoupling of the
hierarchical levels by controlling water content and hece affecting the degree
of shear transfer from one level to the next).
Hope that helps.
Julian
Quoting Abby Ingram <[log in to unmask]>:
> Hi
>
> Not sure about the hedgehog spines. Are the leaves and debris, often found
> attached to the spines to camouflage the animal, simply impaled on pointed
> tips or are they hooked by curved spines? Could be interesting. As to the
> antlers, you might want to look at D'Arcy Thompson's book, 'On Growth and
> Form'. It's a classic and analyses biological processes and the resultant
> forms from their mathematical and physical aspects. There are chapters on
> the shapes of horns, teeth and tusks and also on spicules and spicular
> skeletons (re. spines?).
>
> Abby Ingram
>
> Dr A. L. Ingram
> Dept of Zoology
> University of Oxford
> South Parks Road
> Oxford OX1 3PS
> UK
> Tel: 01865 271224
>
--
Julian FV Vincent [log in to unmask]
Professor of Biomimetics office 01225 386596
Centre for Biomimetic & Natural Technologies mobile 07941 933901
Dept of Mechanical Engineering fax 01225 386928
The University
BATH BA2 7AY
http://www.bath.ac.uk/Departments/Eng/biomimetics/
I hate quotations. Tell me what you know. (Ralph Waldo Emerson)
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