Tuesday, August 22, 2017

St. Francis and the Lizards


We have now lived in our "new" house nearly three years. The yard came with a small statue of St. Francis. Though we are not Christians, I love the idea of a saint who loved animals watching over the critters who come to visit. From our first days here, there has been one or another Spiny Desert lizard that likes to perch on Francis' head. Here are some of my favorites.

Cedric, a fairly large desert spiny, was the first lizard I named. This is his typical perch--on the side, facing west, his tail relaxed and extending down Francis' cowl. Late in that first summer, I found poor Cedric's body lying on the back porch, his beautiful belly colors still glistening. I have no idea what the cause of death might have been.
Cedric was followed by his girlfriend, unnamed. She was somewhat smaller than Cedric and preferred to sit more securely on the top of the head.
A considerably smaller lizard, whom I named Cedric Jr., appeared the following year:

The lizards have come and gone, but never has warm weather passed without at least one "regular" making him- or herself comfortable on the saint's accommodating head.

This year, I've had a special lizard, a very large female I named Heloise. When I first saw her in this pose, I burst out laughing. 
A few days after I took the photo, I noticed that Heloise had lost her tail. That did not stop her from her favorite activity, however, and finally I discovered why St. Francis' head is so popular. In addition to his function as a sunbathing perch, it turns out he is a hunting blind!
With her tail beginning to grow back, Heloise was in her usual spot the other day. I was puzzled, though, because it was cloudy, not suitable for basking. I was just about to change positions so I could get a shot of her tail stub when she very suddenly leaped off St. Francis' head and literally dived into the lantana bush to the west. I saw her wrestling with a large insect, but couldn't tell what sort it was, or if she managed to eat it. Nevertheless, I feel confident that tailless Heloise will continue to thrive in my Francis-blessed back yard.



Monday, March 13, 2017

How is a Snake Like Ginger Rogers?

It was said of  the actress/dancer Ginger Rogers that she could do everything her partner, Fred Astaire, could do--but she did it backwards and in high heels.

It’s sort of the same way with snakes.
Looking at these amazing creatures, you can’t help but notice how different a snake's outer (superficial) body plan is compared to the four- and two-legged creatures we are most familiar with. And yet--at the same time--snakes are in many ways very much like us--they have a brain, a heart, digestive and reproductive organs, and many other similarities, some obvious and some not so (for example, they only have one functioning lung). They can feed and shelter themselves, protect themselves from danger, procreate--in fact, do just about anything a creature with arms and legs can do…

But they do it all without  arms or legs, hands or feet.  How do snakes manage their amazing acts of survival? They do it through a series of anatomical adaptations that allow them to use their mouths in ways we bipeds could only dream of, and their strong, muscular bodies to help manipulate objects. Let’s take a closer look at how some of these amazing adaptations work.
Image from PetEducation.com
The best place to start is with the skull. Snake skulls are mobile compared to mammal skulls. Whereas our skulls are solid, with the different parts fused together, the separate parts of a snake's skull are more loosely connected, with ligaments, allowing the bony parts of the skull to move in ways our skulls cannot. For example, Instead of a bony inner ear, snakes (and birds) have an extra bone connecting the lower jaw to the skull, which allows a snake to open its mouth as wide as 180 degrees. This ability helps explain how a snake can swallow something bigger than its head.

Another important difference between us and snakes is that the  two halves of a human’s lower jaw are fused together at the chin. Snakes don’t have a chin; instead, their jaws are connected by a ligament, which allows the two halves to move separately. Snakes’ teeth (not including fangs, which are used to deliver venom in venomous snakes) are small, sharp, and pointed backward--toward the gullet. Thus, when a snake has prey in its mouth, its sharp teeth can hold the object tightly while the snake uses the two sides of its jaws alternately to  “walk” the prey back, through the mouth and toward the gullet. No need for a knife and fork, or even for grasping hands or paws.
The snake’s windpipe has a special extension, the glottis, that allows the snake to breathe while it is swallowing something large. As the meal moves further along, the body begins to expand because of another anatomical feature--or rather, the lack of one. Unlike humans and other mammals, snakes don’t have a breastbone to tie the ribs together in the front of the body, so the ribs can expand as the meal makes its way down the digestive tract.

The below photo, by Carlton King, shows how this all works: it is the last in a series of photos showing a kingsnake devouring a diamondback rattlesnake that was seemingly bigger than the kingsnake!


Snakes have  many other amazing adaptations that allow them to live their slithery lives, and I hope to discuss more of them in future posts. I find snakes awesome in every sense of the word, and I hope this short discussion has helped you begin to feel that way too.