Black Snakes (Black Racer & Indigo) Two very different non-poisonous species commonly called by the same name, the Black Racer & Indigo play important roles in our society.  Yes, they kind of have jobs.  Attracted to human populated areas to feed on mice & rats, the slender Black Racer is often seen.  The Indigo Snake is Florida's largest native snake, and spends its days feeding on rodents, small mammals, and other snakes (even venomous ones).  The Black Racer grows to be 21/2 to 3ft while the Indigo reaches lengths of 6-8ft.  How did they get their names?  Well, the Black Racer is fast, and the Indigo takes on a deep blue color right after a shed.  Indigo Snakes are a protected species.