Quote Originally Posted by Witis View Post
I have explicated a means of comparing some of the top sea-borne predators founded on factors such as weapons, defenses and means of escape, although I indicated it was not a black box as each match up has to be customized to ensure that all of the individual factors that come into play are examined in each case.
Explicated? It's a bit late to ask this, but how about actually explicating it. You did say that you had such a thing, but you also stated that we would find it too boring, and left it out for that reason. By now, you probably realize that it wouldn't be found all tha boring. Controversial, perhaps, but not boring. How about sharing it? At least that way we'd all be talking about the same thing.


Are you seriously trying to tell me that the amount of dissolved oxygen is too low for sharks to survive in a large percentage of the world's seas?
Did you read that paper I linked to? It wasn't me saying that. They pointed out that makos won't go below a certain oxygen concentration, and water with lower concentrations are common at relatively shallow depths, certainly depths more shallow than makos would tolerate. I would expect that such hypoxia zones are dependent heavily on local currents and conditions, and I would expect that they are more common in the tropical areas and less so towards the arctic, but I seem to remember also reading that makos don't go into the arctic zones. As a percentage of surface area, this would mean that there are no hypoxia refuges, but as a percentage of volume, it would be a VERY large percentage. Once again, though, that wasn't me stating that. The oxygen tolerance of sharks is well demonstrated, so figuring out the hypoxic exlusion percentage would be just a mathematical exercise....though not a particularly easy one.


I am not convinced the jaw design is limited as you suggest eg http://www.drunkonblue.com/2009/11/t...he-open-ocean/
Interesting link, but I don't see how it is relevant to the jaw question. Once again it talks about the mako preying on relatively small fish. My point is that a sub terminal mouth would have a hard time biting into a flat surface, but would be fine with biting into a sharply curved surface. Most fish would present a sharply curved surface, so it would be fine for a mako mouth. Once you get to the size of an adult whale, the animal, while still technically cylindrical, would be so large that it would approximate a flat surface to the jaws of a mako. Frankly, it seems like the nose of the mako would prevent it from being able to bite a large whate unless it approached from a very peculiar angle. That may be wrong, though, depending on how effective the mako is at projecting its jaw. However, I haven't found any source that even speaks to that, and the link you provided doesn't change that. It's just a matter of geometry, and we might as well disagree about it, but it would be nice to know one way or another, wouldn't it? After all, if it was physically impossible for a mako to bite the side of a much larger fish/whale (and it would have to be MUCH larger, not just a little bit larger), it would pretty much demonstrate that they don't eat orcas.




Terribly sorry old boy.
I have never been unhappy about learning something new in this fashion. It always leads in different directions. Until you started this thread, I had no opinion as to whether sharks ate whales or vice versa. Now, while I still feel that several sharks and a few whales are top predators in the ocean, I'm pretty well convinced that predation between orcas and mako sharks is entirely in one direction, with orcas being about the only animal that eats adult makos (the young of every species is prey to lots of other species).


Thank you Shaggy.
Nothing wrong with you chaning my statement, as long as you recognize that I believe the model to be incorrect, and since that statement is still there, the change doesn't make any difference.

By the way, are you interested in getting in contact with shark researchers to confirm/refute your model, or do you just want to leave it in the realm of armchair determination? It's probably a bit much to pursue it into the academic realm unless you intend to either make a career out of it (I have no idea what you do, or even how old you are), or intend to try to make money from it. On the other hand, I would guess that most shark researchers would be happy to talk about it.