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Rulers of the forest

Hey y’all, this is Ben from the Herpetology Team at Zoo Atlanta. Today, I want to briefly tell y’all a few things about one of my favorite genera of snakes, Drymarchon. The genus, Drymarchon, contains five distinct snake species. These species are commonly known as the indigo snakes or cribos. These species are large, oviparous (or egg laying), nonvenomous colubrids. The Latin name, Drymarchon, is derived from two Greek words: drymos, meaning forest, and archon, meaning ruler. Thus, their scientific name roughly translates to “rulers of the forest.” Once you consider the behavior, diet, and natural history of these animals, you’ll discover that this genus is aptly named.

Often times, snakes are particularly adapted to eating one sort of prey. For instance, most rattlesnake species here in the Southeast have adapted to primarily eat rodents. Another example is the brown watersnake (Nerodia taxispilota), which feeds primarily on fish, mostly catfish in fact. The members of the genus Drymarchon are perfect examples of snakes with a generalized diet. These species are active, diurnal hunters that will consume just about any prey they can catch and overpower. The array of species these snakes can overpower and consume is vast when one considers their size. For instance, the eastern indigo snake (Drymarchon couperi) is North America’s longest species of snake, with the males (the larger of the sexes) reaching lengths of up to eight and a half feet.  This awesome species is native to Georgia and is known to eat prey ranging from birds, rodents, frogs, small turtles, and a variety of snakes, including the largest venomous snake species in North America, the eastern diamondback rattlesnake (Crotalus adamanteus). 
The South American counterpart within the genus is the yellow-tailed cribo (Drymarchon corais). This species has the largest distribution of any species within this genus, ranging from Central Mexico all the way south to parts of northern Argentina, usually inhabiting drier forests and grassland habitats. This species is also known for having a generalized diet; they will often consume frogs, toads, lizards, snakes, birds, eggs, and rodents. This species is the largest within the genus, with adults topping out at around 10 feet long. Unlike the eastern indigo snake (Drymarchon couperi), there is no sexual dimorphism observed in the yellow-tailed cribo (Drymarchon corais), with adult males and females growing to the same size.

Moreover, members of this genus are clearly adapted to eat a large variety of species. Their mechanisms of eating are also unique within the suborder, Serpentes. While most species of snake either constrict or envenomate their prey in order to subdue them, the indigo snakes and cribos have a different approach. Often, these snakes will grab their prey, overpower, and consume them alive. These snakes are also known thrash their prey around to subdue them. While this process seems fairly brutal, it is also awesome! These snakes are true predators and their behavior is a sight to behold! One last awesome adaptation these snakes demonstrate is their ability to eat venomous and poisonous prey. The eastern indigo snake (Drymarchon couperi) will consume venomous snake species without hesitation and is likely immune to the potent cytotoxins and hemotoxins found within many pit vipers’ venom. The yellow-tailed cribo (Drymarchon corais) has been observed consuming bushmasters (Lachesis muta), as well as cane toads (Rhinella marina) and is likely immune to both the bushmaster’s venom as well as the cane toad’s poison. These adaptations for such a varied diet are impressive and clearly demonstrate these species to be rulers of the forest!

Ben M.
Keeper I, Herpetology

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