When people hear the word “poisonous,” they tend to think of poisonous snakes, or perhaps insects that have painful stings like wasps and yellow jackets and angry bees. There are hundreds of species of venomous snakes and thousands of species of poisonous insects and plants.
However, there are some poisonous mammals, too. There aren’t many of them and they are generally small, but poison helps them subdue prey and fight off predators.
Technically, there is a difference between venom and poison. Venom is a poison injected into the body of prey or predator by fangs, like a rattlesnake striking a snake collector’s hand. Poison is not injected, and is more often used defensively, like when a blue jay grabs a monarch butterfly and spits the butterfly out because the butterfly’s body is full of toxins obtained from eating milkweed, which has a poisonous sap.
Venom and poison work in various ways. Poisons are complex substances, and some stop the heart for beating, some stop the lungs from working, some do a fast and devastating attack on the nervous system. Some kill prey so it can be eaten, others result in the predator rejecting prey because of the foul taste. Here are some mammals that use poison.
One of the oddest uses of poison is by the common hedgehog, Erinaceus europaeus. Their cuteness appeals to people, so many are pets. In the wild, however, they lick and chew on the skin of poisonous toads, then spread the poison on the spines on their back. That way if any predator bites their back the hedgehog may be spit out in disgust. Hedgehogs may lick up many toxins, including turpentine and cigarette butts (concentrated, nicotine is a poison). Some experts think it’s a way to get rid of parasites rather than fight predators.
There are several species of Slow Loris, genus Nycticebus, native to Southeast Asia and part of China. They are nocturnal (they come out at night). They range in size from 9 ounces to 4 pounds or so. They eat insects, eggs, birds, smaller mammals. The poison is licked from a gland on the foreleg and when mixed with saliva makes a toxic substance that can be transferred with a bite. Some slow loris species apparently lick their young with the substance when they leave their den, which gives them a bad taste for any predator. It’s not known if they use it to subdue prey. They are no danger to humans, but can give a nasty bite.
Among the most fierce of all predators are among the tiniest, shrews. Several species of shrews use poisons. The Northern Short-Tailed Shrew, Blarina brevicauda, has a neurotoxin in its saliva. This shrew weighs about an ounce, has poor eyesight and uses echolocation to find prey. It has a fast metabolism of 800 to 1200 heartbeats a minute, so it has to eat almost constantly. It consumes what in human terms would be 200 pounds of food a day. Its poison may kill or just paralyze prey. The shrew sometimes drags paralyzed prey back to the burrow to store and have for lunch later.
Some mammals borrow poisons from plants. The African Maned Rat, Lophiomys imhaus, is a rather large rat, up to 6 pounds. This rat searches out poison arrow trees and rubs its back in sap from the plant on the fur on its back. The thick and rather ugly back hair is the “mane” in the animals’ name, and with the hair coated in poison from the poison arrow tree sap, any predator biting the rat is apt to get a painful and distasteful mouthful, allowing the rat to escape.
One of the odder (and uglier) mammals is the Cuban solenodon, Atopogoale cubana. This endangered species grows to 12 inches or so, and weighs up to a couple of pounds. Their diet consists of earthworms, small reptiles, frogs, and similar small creatures. The solenodon is the only mammal that injects its poison into its prey, so it’s the only venomous mammal. They are nocturnal and live in burrows. There is a related species on the island of Hispaniola (Haiti and the Dominican Republic).
Possibly the most unusual poisonous mammal is the Duckbilled Platypus, Ornithorrhynchus anatinus. The platypus has a strange duck-like beak, and lays eggs. It has webbed feet and uses electrical sensitivity to detect prey in the mud in stream bottoms. They range up to several pounds in weight and are native to eastern Australia. The adult males have a spike on their rear legs connected to a poison-producing gland and can slash and expose people to a quite nasty poison. The poison is most intense during mating season, and it may be used in disputes between males. Another odd characteristic is that a platypus glows blue-green when exposed to black light.
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