Rough-skinned newt

Lore & Background

The rough-skinned newt produces a potent neurotoxin, tetrodotoxin, from its skin glands, which acts as a defense against predators. The toxin binds to sodium channels in nerve cells, blocking electrical signals and causing paralysis and death by asphyxiation. In 1979, a 29-year-old man from Oregon died after ingesting one. The newt's toxicity is linked to its skin microbiome, and an acrid smell warns animals to stay away.

Throughout much of its range, the common garter snake (Thamnophis sirtalis) has evolved resistance to tetrodotoxin. Resistant snakes can gauge a newt's toxin level by partially swallowing it and deciding whether to eat or release it. This predator-prey relationship is a classic example of co-evolution, an evolutionary arms race where newts produce more potent toxin and snakes evolve greater resistance. In some areas, snakes have surpassed newts in this race.

Newts themselves are not immune to their own toxin but have a heightened resistance due to a single amino acid substitution in their sodium channels. The toxin is also present in the ovaries and eggs, providing protection to offspring. Additionally, newts can detect chemical signatures from snakes that have digested a newt, triggering avoidance behavior to minimize predation risk.

Reader's Guide

The rough-skinned newt is significant as a model organism for studying co-evolution and toxin resistance. Its relationship with the common garter snake illustrates an ongoing evolutionary arms race, where each species drives adaptations in the other. The newt's tetrodotoxin is the same potent neurotoxin found in pufferfish, highlighting convergent evolution in toxin production across distant lineages. Research on the newt's toxin and the snake's resistance has provided insights into sodium channel function and genetic mutations that confer resistance. The newt's ability to detect predator chemical cues and its use of toxin in egg protection further demonstrate complex ecological and evolutionary strategies. Its presence across the Pacific Northwest, with isolated introduced populations, also informs studies of biogeography and species dispersal. The ongoing debate over subspecies validity, such as the Crater Lake newt, underscores the dynamic nature of taxonomic classification.

Did You Know?

• A 29-year-old man from Oregon died in 1979 after ingesting a rough-skinned newt.
• The newt's toxin, tetrodotoxin, is the same toxin found in pufferfish.
• Some rough-skinned newts secrete enough toxin to kill several adult humans.
• The common garter snake is the only known animal that can eat a rough-skinned newt and survive.