By Deborah Van Hoewyk

One of Huatulco’s major attractions is its natural setting. From the famous “nine-bays-and-thirty-six-beaches,” to waterfalls and wildlife, to mountain trips and horse-back riding, being active outdoors is just at your doorstep. And going farther afield in Oaxaca, you find the lagoons and mangroves of the coast, the frozen white waterfall of Hierve el Agua (literally, “boil the water”), and the hiking trail between the eight villages of the Pueblos Mancomunados (hard to translate, sort of a “community of towns”), to name just a few outdoor adventures.

In all of these environs, you will find snakes. Some are venomous, and some are harmless. Left alone, all of them will leave you alone. But should you not be looking, and step on one, it may well attack you. Here are the venomous ones, what they look like, and where you should be watching out for them.

The Vipers

Rattlesnakes. There are two kinds of vipers in Mexico, and most belong to the genus Crotalinae, the rattlesnakes. In the articles in this issue on snake venom, you will learn that Oaxaca has its share of rattlesnakes. Rattlesnakes are “pit” vipers – they have pits near their eyes that contain heat-sensing organs. The sensors let the snake “see” warm-blooded prey. Most hunt at night, so the heat-sensing is key to being able to strike at their prey in the dark.

There’s the pygmy rattlesnake (Croatalus ravus, with three subspecies) – it’s 18-30 inches long and is found in the mountains. It is the usual mottled brown you associate with rattlesnakes.

There’s the black-tailed rattlesnake (Crotalus molossus oaxacus) – it grows to over 4 feet long, and is found in the desert, mesquite grasslands, and pine-oak forests (in the Sierras between 7,000 and 10,000 feet). It comes in varied colors – brown, yellowish, olive-greeny – but the scales on its tail are black.

The small-headed rattlesnake (Crotalus intermedius) – is small all over, growing to about 24 inches long. It is found in the pine-oak forests on the mountains, and looks like your idea of a rattlesnake.

The famous fer de lance. Another pit viper, even more to be avoided than the rattlesnakes, is the fer de lance (“spearhead,” Bothrops asper). Various species of Bothrops have been called fer de lance, so herpetologists prefer the term terciopelo (velvet) for Bothrops asper (see Julie Etra’s article elsewhere in this issue). The terciopelo looks pretty much like a rattlesnake, although its head is somewhat bigger and flatter, dark on top and light on the bottom. The female terciopelo grows much larger than the male; males can be 4-6 feet long, but females can exceed 8 feet.

You are not likely to see any terciopelos in Huatulco, as they do not like the dry winters. Unlike rattlesnakes, they prefer a moist environment; if you visit the tropical rainforests or cloud forests of the Yucatán or Chiapas, you could indeed find them; young ones like to climb trees.

Given that vipers hunt at night, using their heat sensors, you might want to reconsider any nature adventures scheduled for after dark.

The Elapids

The Elapidae family of snakes are the stuff of nightmares – they have permanently erect fangs (rattlesnakes and terciopelos have hinged fangs) and when ticked off, are exceedingly testy, not to mention exceedingly venomous. Some rise up and spread out the skin of their neck like a hood – think Indiana Jones and cobras.

The Oaxacan coral snake (Micrurus ephippifer and Micrurus ephippifer zapotectus) is found in tropical deciduous forests, as in the Huatulco National Park, or farther up in the pine-oak forests of the mountainsides. These snakes can be quite small, and almost never exceed 3 feet. They like to burrow under leaf litter, logs, forest debris – you won’t see them before you step on them. They are also fond of wetlands, so watch your step on marshy ground.

Sea Snakes

The subfamily Hydrophiinae contains the sea snakes. Note that there are very rarely Hydrophiinae in the Atlantic (a few have been sighted in the Caribbean, but it is thought that humans released them or perhaps they made it through the Panama Canal).

Sea snakes do, however, occur in the Pacific waters of Huatulco, and they are poisonous. They do not attack humans, preferring to strike fish, paralyzing them with their venom so they can chew them up at leisure.

The only one you are likely to see in Huatulco waters is the yellow-bellied sea snake (Hydrophis platurus). This snake is extremely venomous. While its coloring can vary, it is usually black on top and yellow or light brown on the belly, and the colors are clearly separate. Its tail is flattened from top to bottom, has a marked pattern (usually spots), and helps the snake swim. Males are less than 30 inches long, while females can be up to 35 inches long. The water needs to be above 61˚F (16˚C) for long-term survival.

On the other hand, I myself have seen what appeared to be an aquatic coral snake (Micrurus surinamensis) while out watching dolphins. Definitely red, white/yellow, and black. If that’s what it was, it was considerably off course, since its usual habitat is the Pacific waters off northern South America. Of course, it could have been a Oaxacan coral snake wandering off from the wetlands of the Parque Nacional …