Tuesday, April 08, 2008

Black Bead Game

I really wanted to write about the whipscorpion that Phantom Midge found, but I hate to say, there is little to no information about Trithyreus shoshonensis. So, my fall back this week is an animal that I got a picture of during my spring break trip to the Columbus Zoo. Growing up, I remember learning that the Gila Monster was one of two venomous lizards. This is the other one.

Image by Me
Image by me

Yes, the Mexican Beaded Lizard (Heloderma horridum) looks a whole lot like the Gila Monster. This so happens because they are within the same genus, and the major differences are that the Gila Monster is smaller and more colorful. Not having the hinged fangs of vipers, the Beaded Lizard delivers venom that flows along grooves in the teeth, and delivers by chewing. Digimorph gives a wonderful visual of that—check out the horizontal dynamic cutaway1 and watch for the hollow bottom teeth. The venom is used mainly as a defense mechanism, and is typically non-fatal to humans—if you get medical treatment quickly enough. The small animals they prey on…well, that’s a different story.

The “beads” from which this lizard gets its name are osteoderms2: tiny bits of bone growing within the skin that lead to its studded appearance. This adds another layer of protection on top of the fact that they can maim with a single bite. They inhabit the scrublands and other semi-arid habitats of Western and Southern Mexico, explaining the other part of their name. Like some other arid-adapted lizards, the Mexican Beaded Lizard can store fat in its tail to provide food and water during times of scarcity.

Habitat loss, due to clearing for agriculture, is one large factor in this species’ decline. The one that really surprises me, however, is the pet trade. I’ve always been an avid fan of reptiles, and have no problems with keeping some as pets. But I draw the line at an animal that can kill me if improperly handled. To help stop this problem, they are listed by CITES, and there are breeding and head start programs to replenish their numbers in the wild.

1Yes, it’s actually a Gila Monster. The principle is the same.
2Meaning “bone skin.”


Anonymous said...

Shrews also have this kind of drip venom method (or toxic drool if you prefer) which is interesting (although completely unrelated).

Raging Wombat said...

I'm thrilled that Mother Nature determined that the gila monster deserved a cousin. The world needs more venomous lizards, especially of the chewing variety.