Without further ado, the arguments:
Those who think the shark would win:
The winner is undoubtedly the shark. It comes down to two key factors: speed and agility of striking. At its fastest, the shark is faster than a bear so the shark could realistically swim circles around the bear waiting for the right moment to strike its prey. The ability to attack on your terms is key to winning a one-on-one fight. Secondly, a shark can strike with both ends of its body. A quick bite or head-butt can be followed-up by a whipping tail slap. Not only does the shark have the ability to strike quickly and in multiple ways, but it is more agile in its striking ability. Do you really think a bear's claws or teeth are sharp enough to do much damage to a shark's tough skin? Most likely for a bear to win it will have to catch the shark and hold it down while clawing and biting repeatedly. There is no way any animal without opposable thumbs will be able to grab onto a shark, whereas a shark's jaw can open wide enough and clamp down hard enough to render the bear defenseless. Vive-la-shark!
Both animals are strong, and I don't think either animal will score a KO. Both animals will be injured in the fight. I think the animal that loses is the one that bleeds out first. Since sharks have much thicker skin than bears, the bear will be injured more easily than the shark and will thus bleed out and die first.
Key points here: agility, speed, coordination, and quickness (different in speed because quickness is the fast speed of small movements, whereas speed is the overall speed of your movements). Sharks are more agile in the way that they are able to move. The bites and attacks are key, if the bear is even able to get a shot on the shark which probably won't be to the nose and then a bunch more shots would be needed to kill the shark. The shark is able to get one attacking bite on the bear and then just avoid all other attacks that may come from the bear. Eventually, rather quickly actually, the bear will hemorage and bleed out thus, it dies and the shark remains the winner.
The shark is just so much faster and stronger than the bear. One bite and it's over. There's no way the bear could beat the shark with just one punch or something like that. Easy victory for the shark.
Finally, a submission for the shark that is so thorough that it requires its own post.Those who think the bear would win:
A shark only has one weapon: its mouth. A bear has four paws with razor sharp nails in addition to a powerful bite. The bear is capable of latching onto the shark, inflicting maximum damage while the shark is left to try and wiggle free and mourn the loss of it's dorsal fin. Bear wins.
The bear will definitely win the fight. The shark can only swim and bite the bear with its teeth. The bear can move out of the way easier because it has joints and is more free to move around. The bear can also bite the shark, but, in addition, can use its claws. With one swipe the shark is dead, and the bear the victor.
I think the debate comes down to two basic variables - bloodthirst and deadliness. The sharks may have a slight edge in bloodthirst (you don't see no sharks munching on berries), but they're kind of a one trick pony when it comes to deadliness. If you're not in the direct path of their jaws, you're pretty much safe (plus, they're not great at cornering). Assuming the bear has clear visibility (I'll admit, I don't know if a bear can look straight up to watch the attack from above), a shark's attacks are relatively straight forward to parry. The bears, on the other hand, may not have as powerful a go-to move, but they have a plus-plus bite with above average mauling and clawing ability. Versatility goes a long way in cage matches. Plus, sharks have no defense techniques. Say what you will about how furry and chewable bears might be, but they can put their little bear arms over their face, throat, or genitals (the big three) to protect from critical blows. Sharks may not have throats or exposed genitalia, per se, but what they do have (eyes that are right pokable) are completely defenseless.
Bears can swim, run at amazing speeds AND climb trees. They are deadly anywhere, and they also have limbs which give them reach. Sharks can be disabled with a conk on the nose. Bears cannot be "fought off," sharks can. Game over, Bears win.
The bear wins easily. The shark has a big mouth and sharp teeth but the bear can avoid the shark bite by simply using his hands or running away. The shark has no defense to attacks anywhere besides his face too. The bear can use a combination of attacks with his claws and mouth to beat the shark. Also, the bear can attack the shark with his legs not just his hands and claws.
So there you have it. The voting's open on the right. Let's settle this once and for all.