2022 | Sonoran Desert — Zoe Keller Nature Art

Poisonous and venomous organisms both use toxins, but in very different ways. Poisonous creatures and plants use their toxins to defend themselves from predators.1 They are often more passive than venomous creatures, releasing their toxins only when they are touched, attacked or eaten.2 These unappetizing organisms are often incapable of producing toxins themselves.3 Pipevine Swallowtail Butterflies, for example, ingest the toxic chemical of its host plant, the California Dutchman’s-pipe as caterpillars. This toxin remains in the adults, who in turn pass this toxin on to their eggs.4 Many poisonous creatures use color and patterns as a warning to predators. The brightly colored Convergent Lady Beetles use aposematic coloration5,6 as a warning of the toxic chemical in their blood.7 The Queen Butterfly is not the only butterfly to use bold orange and black patterning as a defense; the Queen, Viceroy and Monarch butterflies – all poisonous and distasteful – exhibit Müllerian mimicry,8 a type of mimicry where multiple species share warning colors to help protect themselves from predators.9 While humans are unlikely to be tempted by lady beetles or butterflies, the appealing hallucinogenic properties of the Sacred Datura do occasionally lead to life-threatening poisonings.10 Symptoms of ingesting Sacred Datura can include blurred vision, difficulty breathing and auditory and visual hallucinations.11 These effects made Sacred Datura an important part of the rituals of many indigenous peoples of the American Southwest.12,13

Venomous creatures usually make their own toxins, and must deliver these toxins through a wound:14 a Stripe-tailed Scorpion’s “essentially painless” sting,15 the pinch of a Common Desert Centipede’s pincer-like appendages,16 or a bite. The Sonoran Desert is home to numerous reptiles that deliver their venom through bites. Although its fangs are unusually short,17 the dangerous neurotoxin in the venom of the Tiger Rattlesnake makes its venom the most toxic of any rattlesnake species.18 The venom of the Arizona Coral Snake is also a neurotoxin, although not as potent as that of North America’s other two species of coral snake.19 The Gila Monster, one of the world’s few venomous lizards,20 does not inject its venom through fangs. Its venom is produced by a row of glands in its lower jaw, and then chewed into its prey21 (or an attacking predator)22 with the lizard’s grooved teeth.23 Bites of these three shy, elusive reptiles are unlikely for humans, unless the reptiles are intentionally handled.24,25,26 Although arachnophobes may also expect a nasty bite from the Desert Blonde Tarantula, these docile spiders pose little threat to humans,27 with a level of venom comparable only to a bee sting.28 (Surprisingly, the hairs of the tarantula are what human handlers should worry about! The specially designed barbed hairs on the abdomen of the tarantula can be very irritating29 and, if inhaled, can require hospitalization.)30

The many defensive strategies of the poisonous and venomous organisms of the Sonoran Desert demonstrate the beautiful ingenuity of the natural world, and serve as an important reminder that plants and animals are often best observed, and not touched!