Venomous mammals

Venomous mammals are animals of the class Mammalia that produce venom, which they use to kill or disable prey, or to defend from predators. In modern nature, venomous mammals are quite rare. Venom is much more common among other vertebrates; there are many more species of venomous/poisonous reptiles (e.g. snakes), amphibians (e.g. poison dart frogs), and fish (e.g. stonefish). There are no species of venomous bird; however some birds are poisonous to eat or touch, such as the pitohui, the ifrita, and the rufous shrike-thrush.

There are suggestions that venomous mammals were once more common. Canine teeth dated at 60 million years old from two extinct species, the shrew-like Bisonalveus browni and another unidentified mammal, show grooves that some palaeontologists have argued are indicative of a venomous bite. However, other scientists have questioned this conclusion given that many living nonvenomous mammals (e.g., many primates, coatis and fruit bats) also have deep grooves down the length of their canines, suggesting that this feature does not always reflect an adaptation to venom delivery.

To explain the rarity of venom delivery in Mammalia, Mark Dufton of the University of Strathclyde has suggested that modern animals do not need venom because they are smart and effective enough to kill quickly with tooth or claw; whereas venom, no matter how sophisticated, takes time to disable prey. Indeed, the venomous insectivore, the solenodon, is now being driven from its native habitats by introduced dogs, cats, and mongooses.

Listed below are mammals that are venomous or that use poisonous or noxious chemicals in some form.

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Venomous

Cuban Solenodon (Atopogale cubana) & Haitian Solenodon (Solenodon paradoxus)

Solenodons look similar to big hedgehogs with no coat of spines. They both have venomous bites; the venom is delivered from modified salivary glands via grooves in their second lower incisors.

Platypus (Ornithorhyncus anatinus)

Males have a venomous spur on their hind legs. Echidnas, the other monotremes, have spurs but no functional venom glands.

Eurasian water shrew (Neomys fodiens)

Capable of delivering a venomous bite.

Northern Short-tailed Shrew (Blarina brevicauda)

Capable of delivering a venomous bite.

Southern Short-tailed Shrew (Blarina carolinensis) & Elliot's Short-tailed Shrew (Blarina hylophaga)

Possibly have a venomous bite.

Venomous/poisonous

Slow loris (Nycticebus coucang)

Glands on the inside of their elbows secrete a toxin that smells like sweaty socks. They cover their babies in the toxin to protect them from predators, and put it in their mouths to give themselves a venomous bite, delivering the toxin via their lower incisors.

Chemical defense

Family Mephitidae

Skunks can eject a noxious fluid from glands near their anus. It is not only foul smelling, but can cause skin irritation and, if it gets in the eyes, temporary blindness. Some members of the mustelid family, such as the striped polecat (Ictonyx striatus), also have this capacity to an extent. Pangolins can also emit a noxious smelling fluid from glands near the anus. The Great Long-nosed Armadillo can also release a disagreeable musky odour when threatened.

See also

• Dangerous organisms
• Venomous fish
• Toxicofera - The clade that contains all venomous species of reptile.

References

• Folinsbee K, Muller J, Reisz RR (2007). "Canine grooves: morphology, function, and relevance to venom" Journal of Vertebrate Paleontology 27:547-551.

• Fox RC, Scott CS (2005). "First evidence of a venom delivery apparatus in extinct mammals". Nature 435 (7045): 1091-3. PMID 15973406

• Orr CM, Delezene LK, Scott JE, Tocheri MW, Schwartz GT (2007). "The comparative method and the inference of venom delivery systems in fossil mammals" Journal of Vertebrate Paleontology 27:541-546.