Evolution is a neat thing. It gave birds more effective wings, cheetahs speedier hunting skills, people better posture, and the shark absolutely nothing. Many animals with limited strength-type defenses are given other ways to keep themselves out of harm's way. Spiky fishes that puff up, lizards with silly collars, and that thing that hippos do with their tails, are great examples.
This frog has a great one. Might work for the average subway rider too.