Wednesday, April 16, 2008


This will not be the first time I’ve written about things with exciting nasal protuberances. I don’t find these noses ugly—they all do nifty things, and I can’t help but write about them.
Image from Elasmodiver
Image from Elasmodiver

The rostrum of Green Sawfish (Pristis zijsron) is no exception. It uses its saw mainly for feeding—swiping at unsuspecting fish, stunning and injuring the intended prey, or raking up tasty crustaceans from the seafloor. The Sawfish is closely related to sharks and rays, and, like them, has sharp scales called denticles; these have been modified to form the “teeth” of the saw. Catching food is not the only thing the rostrum is good for, as it is lined with motion- and electric- sensing pores to find buried prey. That, and if anything happens to appear threatening, it couldn’t hurt to have a spiky protrusion on… um… hand.

I thought Wikipedia had a typo when it stated that the Green Sawfish grew as large as 7 meters—surely, they must mean feet. Nope. This is a big fish. They reach maturity at 14 feet. Think of the length of a typical bedroom. A little more than half of that is filled with a fish that looks halfway between a shark and a ray. The other five and a half feet is a nose with spikes. Don’t worry; humans are much too large to be considered prey, though you might not want to provoke them.

The Green Sawfish is the most common sawfish. It’s also critically endangered. That doesn’t bode too well for the other species. In fact, the Common Sawfish (Pristis pristis) is pretty close to becoming extinct. The biggest threat to all sawfish is accidental by-catch by the fishing industry. Let’s face it, with a proboscis like that, getting tangled in nets would not be pleasant. Less frequently, they are caught on purpose—for meat, for oil, or for an interesting six-foot long spiky thing. As of yet, they are only beginning to set conservation measures into place.

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.”