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Venomous Animal Spotlights (8)

Tucson has its fair share of venomous animals. However, only a few are considered potentially life-threatening to most people (see list to left). Nonetheless, it pays to be cautious. Never place your hands or feet anywhere you cannot see (e.g., into burrows or shrubs, under rocks or wood, etc.). If bitten, immediately call the Arizona Poison and Drug Information Center at 1-800-222-1222 and seek medical attention if you are unable to call. I have included general information about venomous animals below.


Animals that produce toxins are generally called poisonous. Victims can be poisoned in two ways -- by ingesting the toxins (e.g., by biting a frog that has produced toxins on its skin) or by envenomation (e.g., by being stung by a wasp or bitten by a rattlesnake). Thus, you are bitten or stung by venomous animals, but you have to do the "biting" to be poisoned by a poisonous animal. Mechanisms used to envenomate include hair (e.g., urticating hairs of caterpillars and tarantulas), modified egg-laying devices (e.g., stingers in wasps), and of course teeth (with venom groove on outside or hollow inside).

Animals use toxins offensively, defensively, or both. Offensively, animals use toxins to subdue prey, and in some cases, to begin the digestive process. Defensively, animals use toxins to avoid predation and other threats. However, venom is costly to produce and valuable for subduing prey, so using venom defensively is a last resort. Many venomous animals are either cryptically colored (to avoid being spotted in the first place) or are aposematically colored (as a warning) (see When to Blend and When to Show Off).

The effects toxins have on the victim (mild to fatal) depend on the type of toxin, the amount of toxin delivered, how/where the toxin was delivered, and on the individual characteristics of the victim (species, age, health, individual sensitivity, etc.). Some toxins (hemolytic toxins) break down blood tissue, other toxins (neurotoxins) affect the nervous system, and other toxins have other effects (e.g., severe pain, tissue damage, etc.). An animal may produce a mixture of toxins, resulting in a combination of effects (e.g., rattlesnakes often have both hemolytic and neurotoxic elements in their venom).

Despite the prevalence of venomous animals in and around Tucson, fatalities are extremely rare. For example, despite having more species of rattlesnakes (11) than any other state in the U.S., research conducted by the Arizona Game and Fish Department and the Arizona Poison Center System found that you are more likely to be killed by your spouse than by a rattlesnake in Arizona (4 fatalities of 1,912 bites reported between 1989 and 1998) (Randy Babb, personal communication). If you are bitten, call the Arizona Poison and Drug Information Center at 1-800-222-1222.

Why only Female Wasps, Bees, and Ants Sting

The stingers of wasps, bees, and ants are modified ovipositors -- egg-laying organs that have been modified to deliver venom instead of eggs. Males don't lay eggs so didn't have an ovipositor to be modified into a stinger.

snakesWhen to Blend and When to Show Off

Species that blend into their environment (e.g., this Western Diamondback Rattlesnake) are said to have cryptic coloration. Species that are conspicuously-colored (e.g., this Sonoran Mountain Kingsnake) are said to have aposematic coloration. If you are a delicious morsel, then you want cryptic coloration. If you are poisonous, there are two strategies -- use cryptic coloration so as not to be found in the first place, or use aposematic coloration to warn the potential predator that you are dangerous, thus saving the potential predator from poisoning and you from a bite or from wasting any precious venom.

But alas! This Sonoran Mountain Kingsnake (Lampropeltis pyromelana) is NOT venomous, it is just mimicking the coloration of the Coral Snake that is venomous. This is called Batesian Mimicry, and the Sonoran Mountain Kingsnake is referred to as the Batesian mimic and the coral snake is referred to as the model.

hognose snakeThen again some species --like this Western Hognose Snake (Heterodon nasicus) -- have both cryptic and aposematic coloration. Normally, the snake is cryptically-colored and difficult to spot, but when the snake is threatened, it will coil up and show its underside that is aposematically-colored orange and black (it is also feigning dead). Note: this snake has only mildly toxic venom and is not prone to bite humans.