Newts are amphibians recognized for their unique life cycles, often bridging aquatic and terrestrial environments. These creatures possess a notable defense mechanism. A common question pertains to their toxicity and whether they pose a danger to humans or other animals. Understanding this is important for safe interaction.
Are Newts Poisonous?
Many newt species are indeed poisonous, primarily due to the presence of a potent neurotoxin called Tetrodotoxin (TTX). This toxin is the same substance found in other well-known toxic animals, such as pufferfish and the blue-ringed octopus. TTX is an extremely powerful paralytic that interferes with nerve signals, preventing nerve cells from communicating with muscles. The concentration of this toxin can vary significantly among different newt species and even within populations of the same species, influenced by geographic location. For instance, the rough-skinned newt (Taricha granulosa) found in western North America is known for its high levels of TTX, with some individuals carrying enough toxin to be lethal to several adult humans if ingested.
How Newts Produce and Use Their Toxins
Newts do not deliver their toxins through bites or stings; instead, the neurotoxin is secreted through specialized glands in their skin. These granular glands release a milky, toxic substance when the animal is stressed or handled. This secretion acts as a deterrent to predators, making the newt unpalatable or deadly if consumed.
While it was once thought that newts produced TTX themselves, recent research suggests that some species, like the rough-skinned newt, may rely on symbiotic bacteria living on their skin to produce the toxin. These bacteria, including strains of Pseudomonas, have been identified as TTX producers in other toxic marine animals. The danger to humans arises from handling newts and then inadvertently transferring the toxin to mucous membranes, such as the eyes or mouth, or by ingesting it. The toxin serves as an effective, passive defense, discouraging potential threats through chemical means.
Symptoms of Exposure and What to Do
Exposure to newt toxins can lead to a range of symptoms, from mild irritation to severe effects, depending on the amount absorbed and the route of exposure. If the toxin comes into contact with skin, it may cause localized tingling or numbness. More severe symptoms occur if the toxin is ingested, including tingling and numbness of the lips, face, and extremities, followed by drooling, vomiting, diarrhea, and abdominal pain. As the toxin progresses, individuals may experience muscle weakness, dizziness, and incoordination. In more severe cases, it can lead to paralysis, difficulty breathing, and cardiac arrest.
If contact with a newt occurs, wash hands thoroughly with soap and water immediately, avoiding touching the face until hands are clean. If symptoms develop or ingestion is suspected, seeking prompt medical attention is crucial. There is no specific antidote for TTX, so medical treatment focuses on supportive care.
Distinguishing Newts from Salamanders
Newts are a type of salamander, meaning all newts are salamanders, but the reverse is not true. This can lead to confusion, as both are amphibians with similar appearances. However, physical differences can help distinguish them.
Newts typically have rough, granular skin, especially during their terrestrial phases, while many other salamanders tend to have smooth, moist, and shiny skin. Newts are often more adapted to aquatic or semi-aquatic lifestyles as adults, possessing webbed feet and paddle-like tails that aid in swimming. Salamanders often exhibit longer, more rounded tails and more developed toes suited for walking and digging on land.
While newts may have a terrestrial “eft” stage with bright coloration, their adult forms are often semi-aquatic. The level of toxicity also varies significantly, with newts generally being more potent than many other salamander species.