Meet the
alpheidae, better known as the pistol shrimp.
Now, at 3-5 cm in length, the pistol shrimp isn't a particularly large sea monster. It also doesn't have pincers. What it has is a
biological death-ray which can create bubbles reaching temperatures of 4,700 degrees Celsius (the Sun being about 5,500).
It does this by
cavitation; a bubble is produced which travels at around 97 km/hour and hits volumes of up to 218 decibels.
There you have it - the ocean's most hardcore creature is a 2-inch shrimp.
The world is awesome.