The eastern indigo snake is an even blue-black coloration, with some specimens having a reddish-orange to tan color on the throat, cheek and chin. This snake received its name from the glossy iridescent blackish-purple sheen it displays in bright light. This smooth-scaled snake is considered to be the largest native snake species in the United States. The longest recorded specimen measured 2.8 m (9.2 ft). Unlike many snakes, mature male indigo snakes are slightly larger than females. A typical mature male measures 2.13–2.36 m (7.0–7.7 ft) and weighs 3.2–4.5 kg (7.1–9.9 lb), whereas a mature female typically measures around 2 m (6.6 ft) in length and weighs 1.8–2.7 kg (4.0–6.0 lb). In specimens over 2.6 m (8.5 ft), these snakes can weigh up to 5 kg (11 lb). Although the indigo snake is heavier on average, unusually large specimens of the co-occurring Eastern diamondback rattlesnake can outweigh them.
