Haha, sorry about assuming the teeth were length 0 or 1, it's been ages since i saw one in a game. I guess that'll teach me not to check my assumptions.
The length 5 teeth could be so that the rider doesn't get poisoned when the shark bites the enemy. When the first form dies, it is just a large shark, correct? In that form I would expect it to have length 0-1 on its bite.