SRD:Medium Shark

=MEDIUM SHARK=

These carnivorous fish are aggressive and liable to make unprovoked attacks against anything that approaches them. Smaller sharks are from 5 to 8 feet long and not usually dangerous to creatures other than their prey. Large sharks can reach around 15 feet in length and are a serious threat. Huge sharks are true monsters, like great whites, that can exceed 20 feet in length.

Combat
Sharks circle and observe potential prey, then dart in and bite with their powerful jaws.

Blindsense (Ex): A shark can locate creatures underwater within a 30-foot radius. This ability works only when the shark is underwater.

Keen Scent (Ex): A shark can notice creatures by scent in a 180-foot radius and detect blood in the water at ranges of up to a mile.

Skills: A shark has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

See Wikipedia Entry: Shark