I know that a polar bear is considered a "class 1" animal due to the
research done on my last question. My new question is why is a killer
whale or a dolphin not listed in the classes? Killer whales are
dangerous animals that could potentially injure or kill someone. Would
they be listed as dangerous animals under another heading because they
are marine mammals?

The easy answer is that killer whales are NOT dangerous:

">Are Killer Whales dangerous?
>

THAT depends on whether or not you are a gray whale.  Actually, there are
two known 'types' of killer whales in the world.  One type is known as the
'resident' killer whales - they live in very tightly-knit groups called
pods and have small, local homeranges.  This type is only dangerous to
fish, since that is what they eat, almost exclusively.  The other type is
the 'transient' killer whales - now these are the killer whales that will
eat other marine mammals, such as gray whales, dolphins, and seals.  These
whales are less known than the resident type, but we believe they live in
family groups that travel through much larger homeranges.  These whales
have even been seen to tackle a great white shark.  BUT, despite that,
there has never been a documented case of a killer whale attacking a human
in the wild.  So, I would have to say that no, killer whales are not
dangerous to us."

I doubt that anyone has been attacked by a dolphin, either. Polar
bears are an entirely different story-- they're the most dangerous
kind of bears.

The above is taken from:

http://whale.wheelock.edu/archives/ask98/0275.html

The classification system is not so much to list potentially dangerous
animals per se, but to define under what conditions they must be kept
by persons owning, exhibiting or selling them.  I suppose that the
state of Florida and others don't anticipate this occurring.