The porcupine fish has two merged teeth in each jaw, that make a hard beak-like thing. This allows the fish to crack down hard on crunchy prey. Also, obviously it has spines that make it nearly impossible to eat.
The skipjack tuna is one of the faster moving tunas, allowing the tuna to get away from predators. Skipjack tunas also travel in schools, allowing for higher survival rates.
The smooth hammerhead shark, has a wide face, with eyes on the side for better peripheral vision. This shark also has shark sets of teeth to help tear apart the prey it's hunted.
BIOTIC FACTORS OF TROPICAL OCEANS