You laugh, but I can think of a good half-dozen JWs who would come up with some variation of the above as an explanation.
I've actually had that discussion with JW's and didn't know whether to laugh or just weep for them.
That's the "Existing features were put to a different use than what God originally intended" argument, which orginated with St. Augustine.
It's a form of the fallacy of reductionism. We could argue over the intended purpose of a propeller if the propeller is all we had. But when the airplane is considered as an integrated whole from nose to tail, the function of the propeller becomes self apparent. The design of the whole is a higher level of design than that of the component parts and with an airplane, it is no less the product of a designer.
It's especially interesting to me, that prior to Darwin, this fact was invoked as an argument against evolution. For example, the French Naturalist, Georges Cuvier said:
"That the claws may be able to seize the prey, there must be a certain amount of flexibility in the toes, and of strength in the nails; and this requires a peculiar form of the bones, and a corresponding distribution of the muscles and tendons. The fore-arm must possess a certain facility in turning, whence also result certain forms of the bones of which it is made up; and these bones of the fore-arm articulating to the humerus, cannot undergo change without corresponding changes taking place in this latter bone. The bones of the shoulder, also, require to have a certain degree of strength when the anterior extremities are to be used in seizing prey; and in this way again, other special forms become involved."
Cuvier understood that it's not just claws or teeth that make a predator; it's the integration of teeth and claws with the rest of the body. (Which would not be necessary for a creature gathering things like coconuts that don't actively try to evade capture. ) This is especially problematic for JWs when it comes to creatures with either tiny brains or no brains at all. Did the jellyfish and starfish just decide one day that they were going to be predators? What did they make that decision with?
So although JW's believe in creation, they don't understand and actually reject one of the basic building blocks of creationism.