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Mammals of the Toxic Kind!

Devin Smith, MD
with Jason Hack, MD

It's a day like any other...you clock in for your cage cleaning job at the zoo. However, you've been assigned to a traveling exhibit: "Toxic Mammals of the World." Let's learn a little bit about the creatures you'll be encountering so you can protect yourself. Keep them at broom's length because they can be vicious!
Europeans first encountered the platypus in the late 18th century; a pelt & sketch were sent back to Britain where scientists assumed a joke was being played on them. Despite the initial reluctance, the scientific community has now accepted that the platypus exists. The creature is born with a kerritin spur attached to the ankles of both hind limbs. These fall off of females early on, but the males grow on to develop venom from crural glands attached to the spur. They have venom year round, but it increases during their mating season. Side note: don’t mess with the platypus during mating season (June-October). The venom is made of approximately 19 compounds.

The stings have been noted to be made worse by application of ice packs and only partially relieved by Bupivicaine. Immediate swelling & pain occurs at the site of the sting; victims have reported regional hyperalgesia that remains for weeks to months after the encounter. Typical pain medications, such as opiates, aren’t helpful. Platypus venom is being studied to look for additional “pain pathways,” & may serve as inspiration for new classes of pain meds…one day. If stung, immobilize the site & place a pressure dressing against it. These creatures are warm blooded, produce milk for their offspring, are marsupials, lay eggs, & are the only “mammals” to use electrolocation to pick up their meals. They close their eyes, nostrils, & ears every time they dive & rely solely on their electrical sensing cells at the base of their bill. 

SolendonsSolendons:  Tooth
These cool creatures get their name (which means grooved tooth) from their incisors that through a channel connect to a gland. This gland is where the Solendon's venom is stored; they are in fact the only mammal to be able to inject venom through a bite, due to this impressive dental design. 

MongooseThese clumsy creatures are not equipped with speed or agility, so this toxic technique is what helps them survive, albeit in very low numbers. The Solendon was thought to be extinct between the years of 1890 & the 1970s; as of now, only 37 have been captured for scientific study. They have numerous predators including the ravaging mongoose (think Ricky Ticky Tavi).


There are numerous species of shrew that are venomous, including the American Short Tailed Shrew.  
The venom is made up of proteases (killikrein-like) that cleave enough proteins to paralyze & even kill small mammals, should they so choose). These bites are severely painful to humans as well, so don't handleMole the shrew! Their venom runs into their saliva from the submaxillary glands they are equipped with. Often, like the European Mole   (also venomous but only getting honorable mention)  which paralyzes earthworms in similar fashion, the toxic shrew will hoard its living victims for long periods of time in order to ensure a constant food supply during the colder months.


SSlow Lorislow Loris: Slow Loris 2
While this cute, endangered little guy may appear harmless, he packs a wallop. The slow loris is equipped with venomous glands in the antecubital fossa. When threatened, the loris will lick the gland & sink their teeth into its predator. The venom & saliva individually have not been found to be of great significance, but together they hurt and have driven away bears & even killed a person. Batrachotoxins, which are cardio & neurotoxic, have been found in the combination of fluid produced by the slow loris. In addition, the loris will use its venom to coat the young. Its speed, which it is named for, makes the loris a vulnerable creature. The venom baths they receive as a youth protect them from otherwise hungry predators. Those in the slow loris business often keep tanks of water nearby in case they are bitten; they dunk their limb with the loris attached hoping the creature will release its bite, and therefore releasing less venom. It is suspected that their diet in the wild contributes greatly as those in captivity lose this potent protein group. Let’s hope the zoo has been choosing its food wisely… 


A Few Sources
1) www.genomebiology.com/2010/11/9/r95
2) www.platypus.asn.au/matters_of_life_and_death.html
3) www.arkive.org/hispaniolan-solenodon/solenodon-paradoxus/
4) Kita et al. (2004) “Blarina toxin, a mammalian lethal venom from the short-tailed shrew Blarina brevicauda: Isolation and characterization.” Proc Natl Acad Sci USA. 101(20): 7542-7.
5) http://Bioweb.uwlax.edu/bio203/s2013/gustafso_alli/venom.htm


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