Helicoprion (CR 5)

Large Animal (Aquatic)
Alignment: Always neutral
Initiative: +7 (+3 Dex, +4 Improved Initiative); Senses: blindsense, keen scent, Listen +3, and Spot +15

AC: 18 (-1 size, +3 Dex, +6 natural), touch 12, flat-footed 15
Hit Dice: 8d8+35 (71 hp)
Fort +10, Ref +9, Will +3
Speed: Swim 60 ft.
Space: 10 ft./5 ft. (10 ft. with bite)
Base Attack +6; Grapple +15
Attack: Bite +10 melee
Full Attack: Bite +10 melee
Damage: Bite 2d6+7
Special Attacks/Actions: Ferocity, lashing bite
Abilities: Str 20, Dex 16, Con 18, Int 1, Wis 12, Cha 2
Special Qualities:
Feats: Alertness; Improved Initiative; Improved Natural Attack (bite) B; Toughness
Skills: Listen +3, Spot +15, and Swim +8
Advancement: 9-14 HD (Large), 15-24 HD (Huge)
Climate/Terrain: Any aquatic
Organization: Solitary or school (4-12)
Treasure/Possessions: None

Source: Dragon #318

Ferocity (Ex): A helicoprion is such a tenacious combatant that it continues to fight without penalty even while disabled or dying.

Lashing Bite (Ex): A helicoprion's bite has a reach of 10 feet. It gains a +2 bonus on attack and damage rolls with its bite against targets within 5 feet.

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

Skills: A helicoprion 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.

A helicoprion often circles around prospective prey for a few rounds before swimming in to take a few experimental bites.

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.