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SON OF SON OF RESPONSE.. HORSE HEADS AND TYRES



>      By the way, off the subject....I think the silouette of a guy
> on a surfboard looks about as much like a seal as a frog looks like
> a weasel.  I think it is at least as likely that shark attacks are
> taste tests rather than mistaken idenity.  Its strange and
> unfamiliar, but it apparently alive and hasn't done anything
> aggressive, so why not try a nibble?  Its probably edible.  Garbage
> like horse heads and tires have been found in shark stomachs, but I
> don't think anyone will argue they thought it was a seal.
> 
> LN Jeff

I have to post this on the list to defend my viewpoint, but please
understand that I'd rather not. Jeff's points are an interesting test
of hypotheses about _Carcharodon_ attacks - unfortunately they are
bunk.

First off, the silhouette of a guy on a surfboard, or even just the
silhouette of a surfboard, is clearly enough like a prey animal to
motivate the shark into an attack. Ichthyologists have tested sharks
with variously shaped silhouettes and while they reject some, they go
for others. I won't discuss this any further for fear of spinning at a
tangential. If they are mere 'taste tests', why have the sharks been
seen to expend as much energy as they _do_ when attacking surfboards?
There is good footage of a number of sharks rushing a board from
below, hitting it with all their force, and blasting right out of the
water.  That's a FULLY FLEDGED PREDATORY RESPONSE to the object, and
exactly the same thing they do with elephant seals etc. It's not the
slow, thoughtful circling and gentle mouthing of an object that the
sharks do when they encounter such.

Your suggestion that sharks (and please note that I *was* discussing
ONLY the Great white) might 'try a nibble' just because the object is
unfamiliar doesn't apply to _Carcharodon_, an animal that has only
been recorded attacking objects that it can [thinks it can]
identify. These are fishes and marine mammals, and objects that look
enough like these for the shark to think that's what they are.

Finally, 'garbage like horse heads and tyres' have *not* been
recovered from _Carcharodon_, but from other sharks like tigers
(_Galeocerdo_) and sleepers (_Somniosus_). These operate in
fundamentally different ways from _Carcharodon_, the latter doesn't
cruise around swallowing any old crap. The evidence suggests that
surf-board attacks *are* cases of mistaken identity.

Numerous caveats in the behaviour of _Carcharodon_ don't make it a
good model for tyrannosaur macropredation, incidentally.

There are a couple of shark discussion lists where stuff like this
truly belongs, my apologies for posting it here.

"Your son has been provident in the alliances that he's created - the
last thing we need is a 'martyr' crusade"
"But, if he should learn of my involvement?"
"You're your own man Bill, you always have been. But I strongly
encourage you in that event.................... to deny everything"

DARREN NAISH