SRD:Manta Ray

=MANTA RAY=

These fish are nonaggressive and generally avoid contact with other creatures. They filter plankton and similar small organisms from the water through their gaping, toothless maws.

Combat
* If threatened, a manta ray uses its size and weight to ram opponents. This is treated as a secondary attack.

Skills: A manta ray 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: Manta Ray