Giant Manta Ray
Mantas resting on shallow sea bottoms blend in, gaining a +10 bonus to hide. Giant mantas swallow their prey whole (if human -sized or smaller) on a critical hit with their bite attack, doing an automatic 1d6 damage each round to swallowed prey. A swallowed creature can attack from within, provided it has a small weapon to hand, but has a cumulative -1d penalty to attack rolls, damage, and/or spell checks each round while swallowed. Giant mantas can also attack with their tail spines, requiring a DC 12 Fort save to prevent being stunned and unable to act for 2d4 rounds (possibly resulting in drowning). All manta rays are reasonably intelligent for fish, but some manta rays (between 5% and 20%, depending upon location) are touched by the fish - demon -god Ixitcha, becoming very intelligent with 1d3 cleric levels each. These demon -touched manta rays gain sharp teeth, and do +1d6 damage when biting. Their alignment becomes Chaotic. Worse, some demon -touched mantas are especially favored by the demon -god, and they regenerate 3 hp per round so long as they are alive. The bites of these favored mantas also requires a DC 15 Will save to prevent 1d3 Personality damage. Other names: Devil fish.
Summary
Init +0; Atk bite +3 melee (2d4) or tail spine +0 melee (2d3 plus stunning); AC 18; HD 5d8; MV swim 50’; Act 1d20; SP camouflage +10, swallow whole, stunning (Fort DC 12 or unable to act for 2d4 rounds), crit 19 -20; SV Fort +7; Ref +3; Will +5; AL N. These large fish grow 1d6+17 feet across and about half as long (without tail). Giant manta rays are 2d6+32 feet across. They glide through tropical, and some temperate, waters, hunting for prey – largely consisting of zooplankton, although giant manta rays may consume much larger prey, and have even been known to attack human swimmers.