A parody of "My Grandfather's Clock"

THE SALTWATER CROC

I'm a saltwater croc, that has had his claws docked
And my jaws are secured with strong wire
I've been trained to pursue, every Oz swimmer who
Shows signs that they're starting to tire
If my nose hits their toes, then away they must go
And leave distance between them and me
For although I am bound, my handler has found
Just a nudge and a swimmer will flee

I was one day assigned, to trail close behind
A swimmer who's in a big league
And as I approached, as directed by coach
I detected some metal fatigue
I seized on my chance and I lunged for his pants
And my muzzle no longer held fast
I dined on his nethers, his torso was severed
But the finishing time was world class