Thursday, May 28, 2015

Tale of a Lost Tail

The Desert Spiny lizard (Sceloporus magister), is among the most prominent creatures greeting visitors at Tohono Chul Park in the warm weather. Big, bold and beautiful, with striking colors and eye-catching behavior (these lizards, especially the males, frequently do pushups to advertise their fitness and attract mates), spinies say "Sonoran Desert" as surely as does the saguaro.  
Like other members of the Iguanid family (and other lizards, including geckos), a desert spiny can lose its tail to a predator in a process called autotomy, in which the tail breaks along a fracture plane between two vertebrae. Studies have shown that the lizard is handicapped for some time afterward while it grows a new tail, but it is obviously much better off  than if it had been eaten by the predator!

The tail that regrows is not the same as the original, however. Instead of new vertebrae for support, the regrown tail is composed of cartilage, with long muscles running its length (rather than shorter sets of muscles, as in the original tail). Studies have shown that the new tail does regrow nerves, though it is not known how they compare with the originals.
Above is a photo of a beautiful male spiny I saw at Tohono Chul Park this week, who had fairly recently lost his tail. The photo below more clearly shows the cartilagenous new growth. For a photo of an intact male and the female he has just mated with, see the bonus question in my recent nature quiz

Sunday, May 10, 2015

Late Spring Nature Quiz

This is our first nature quiz in quite a while. Here are five photos of plants and animals that are found in the Arizona Upland portion of the Sonoran Desert. Can you identify them? (Note that all photos were taken at Tohono Chul Park.)

1. This extremely fragrant plant is attractive to bees, butterflies, and human noses. What is its common name?

a) Kidneywood
b) Bladderwort
c) Spleen sticks
d) Herbert

2. This photo graphically presents three icons of the Arizona Upland. What are they?

3. What are the brilliant neon blue fish in this photo?
a) Blue Tetras
b) Cactus Crappies
c) Desert Pupfish

4. What in the world made these odd sandy excavations?

5. What kind of lizard is this? Is it male or female?

1. This is kidneywood (Lignum nephriticum), a fairly common shrub of the arid southwest. Its bark was used traditionally as a diuretic, hence its name. The flowers have a beautiful, bright sweet scent that becomes stronger when they are heated by the sun.

2. This photo shows a white-winged dove and Gila woodpecker enjoying the blossoms of a saguaro cactus. The saguaro is indeed an icon of the Sonoran Desert, as this is the only place in the world where it grows (and mostly in the Arizona Upland). The white-winged dove is an important pollinator of the saguaro, and the Gila woodpecker is well-known for making holes in saguaros that are used as nests.

3. These small, beautiful fish are endangered Desert Pupfish, which are kept as breeding populations by both Tohono Chul Park and the Arizona-Sonora Desert Museum. In spring, when the weather begins to get warm, the males show their sexual readiness by turning this brilliant shade of neon blue. 

4. These small depressions, or "pits," are made by antlions, tiny insect larvae that trap and eat ants. Each pit is created in loose sand by a larva, which then waits at the bottom for an unwary ant to fall into the trap. If the ant should regain its footing on the slide down, the larva throws sand up at it, usually sending it tumbling to the bottom where it becomes a meal.

5. This beautiful reptile is a female Desert Spiny Lizard (Sceloporus magester). When she is sexually mature, her head turns rosy pink to orange. Her better half has beautiful bright colors on his back and his belly. These are the large lizards often seen doing "pushups," which is the male's way of displaying his colors to females and rival males.

What do you suppose these guys have been up to? Please post your guess--or, even better--what you imagine they are thinking, in the comments.

5 points: You must be a nature docent!
4 points: You are at home in the desert.
3 points: You think the desert is beautiful, but would never spend the summer here.
2 points: You guessed randomly, right?
1 or 0 points: You'd really rather stay indoors.