Thursday, May 31, 2007

Venomous mammals

Until recently, I was completely unaware that some mammals are venomous. This discovery dates from over 50 years ago, yet it is a neglected area of research considering how much attention is given to other venomous phyla for their medicinal properties. I had seen the spurs on the hind legs of platypoda, but most monotremes (other than the platypus) have spurs without functional venom glands.

Yet shrews actually have a venomous bite: the bottom canines have deep grooves which deliver the venom produced by specialized salivary glands. These insectivores use the venom to paralyse their preys for up to 16 days, so that they can store them for a later snack. The active component of the venom, called blarinasin (BLTX), shares about 50% identity with human tissue kallikreins. This mode of action is the same employed by other venomous species such as the rattlesnake: "BLTX converted kininogens to kinins, which may be one of the toxic pathogens, and had dilatory effects on the blood vessel walls. The acute toxicity and proteolytic activity of BLTX were strongly inhibited by aprotinin, a kallikrein inhibitor, suggesting that its toxicity is due to a kallikrein-like activity of the venom". A bioprospecting company based in the maritime, at Mt Allison University, is looking to develop this toxin for neuropathic pain applications.

Solenodon are also venomous. They are possibly one of the funniest looking mammals (shown above), like the lovechild of a shrew and an elephant, measuring about 30cm, grunting like a pig, with tits on its ass, and glands in the armpits that make it smell like a goat. As a note to intelligent design believers, they are susceptible to their own venom (better not bite your tongue), they freeze when they sense danger, and they have difficulty running, often stumbling and tripping over their own toes and tumbling over, making them easy targets. Originally from the Caribbean, they are all but extinct due to pets. I guess the bite didn't pack enough punch.

Finally, I was surprised to learn that there is a venomous primate on the island of Borneo and much of South-East Asia. The slow loris is a nocturnal animal which secretes a toxin in its saliva, and mothers lick their offspring before letting them forage for protection.


Anonymous said...

Hi -- just read your post and thought that I would point out that the slow loris doesn't actually secrete a toxin in its saliva. The toxin is produced by a gland on the arm, and the loris licks it and mixes it with its saliva.