The subterranean mole is familiar to anyone who has tended a lawn, but its biological capabilities are often misunderstood. These insectivorous mammals, belonging to the family Talpidae, spend most of their lives tunneling underground in search of prey. While most moles are harmless, certain species possess a unique chemical adaptation. Most moles are not venomous in the classical sense, but a few carry a potent, paralyzing toxin in their saliva.
The Direct Answer: Are Moles Toxic or Venomous
The difference between a toxic substance and venom depends on the method of delivery. Venom is a toxin actively injected into a victim through a specialized apparatus, such as fangs or stingers, requiring a wound for entry. A toxin, by contrast, is absorbed, inhaled, or ingested; in the case of some moles, it is simply present in the bite. Based on this definition, the mole’s saliva is correctly described as toxic, not venomous, since it lacks a specialized injection system.
Species like the European Mole (Talpa europaea) produce specialized saliva containing a neurotoxin. The glands responsible for producing this substance are enlarged and granular in these species. This adaptation is not universal; many North American moles, such as the Eastern mole (Scalopus aquaticus), lack these glandular structures. Therefore, while a few Old World species carry this chemical, the majority of moles worldwide do not.
How the Paralyzing Agent Works
The purpose of the mole’s toxic saliva is not to kill its prey but to immobilize it, serving a survival strategy. The toxin is a neurotoxin, a protein that interferes with the nervous system’s function. When the mole bites, this substance enters the prey, causing localized paralysis by disrupting nerve-muscle communication.
This chemical immobilization is primarily used against the mole’s main food source: earthworms. The neurotoxin keeps the earthworms alive but incapacitated, preventing them from escaping or decomposing. The mole stores these paralyzed victims in underground food caches, sometimes referred to as larders. Storing live food is a survival mechanism that ensures a steady supply of meals during winter or periods of scarce foraging.
Addressing Common Confusion with Shrews
The belief that moles are venomous often stems from confusion with the shrew, a biologically distinct animal. Some shrews, particularly the Northern Short-tailed Shrew (Blarina brevicauda), are among the few truly venomous mammals. Shrews belong to a different family and are typically smaller with a pointed snout, though they share the mole’s insectivorous and subterranean lifestyle.
The short-tailed shrew possesses modified salivary glands that produce a potent neurotoxin, such as the protein known as Blarina toxin (BLTX). This venom is delivered through grooves in their lower incisor teeth, which guide the toxin into the bite wound. The venom is powerful enough to paralyze larger prey, such as mice, allowing the shrew to subdue animals that might otherwise be too large. The shrew’s venom is more potent than the mole’s toxic saliva, supporting its role in hunting vertebrate prey.
Risk Assessment and Safety
For humans and pets, the risk associated with encountering a mole or shrew is generally low, though the distinction in their bites remains important. A bite from a toxic-saliva-producing mole is unlikely to cause systemic poisoning in a person or pet. The bite may be painful, and as with any animal bite, there is a minor risk of bacterial infection or disease transmission, but the neurotoxin itself poses minimal danger.
A bite from a truly venomous short-tailed shrew, however, can result in noticeable symptoms in a human. While not life-threatening, the venom can cause intense, localized pain, swelling, and a burning sensation that may persist for several days. If a pet is bitten by a shrew, symptoms are likely to be localized, but observing the animal for signs of lethargy or excessive swelling is prudent. The best safety advice when dealing with any small, wild subterranean mammal is to avoid direct handling to prevent bites.